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QB-88 (TF-88) Side Lever Air Rifle

tf88

QB-88 BASICS

Jim P.  DEC. 1999

The Qb-88 AKA the TF-88 is a "pretty darned good" Chinese Air Rifle.  It is a spring powered, solidly built, mostly steel and wood, "real" air rifle (it feels like a gun - not a plastic toy.)  It is a "fixed barrel," "side lever" and these are both good.

"Fixed Barrel" - If you just use the iron sights that come with an air gun, the kind of air rifle that you cock with the barrel is OK, because the sights are on the barrel and will remain in alignment with it, but when you go to a scope in order to assure the alignment of the scope and the barrel a very precise "lock up" mechanism is required - or you can have the barrel permanently fixed to the receiver like the Qb-88 and there is no problem with a scope (for more info see "Mounting a Scope" later.)

"Side lever" - well if you don't use the barrel you have to use something to cock the gun. There seem to be two methods - "under lever" and "side lever."  Either works - the disadvantage to the "under lever" is that your hand has to touch the barrel which is usually blued and oiled.  With the "side lever" your other hand is on the stock and the lever usually has a plastic handle = no oil and no rust on the barrel.

It is a "Direct Loading" type air rifle with "Anti Bear Trap" safety. This is mostly good see "Loading the Rifle with Safety." The other type is the "Tap loading" air rifle and here again precision dictates whether the tap is aligned with the barrel - and if not accuracy suffers.

Let's see, what else?  The Qb-88 has an adult length "semi- target" type stock and most of mine have been pretty nicely finished (though sanding and refinishing the stock always makes the rifle look better.)  And the Qb-88 has an adjustable trigger.  This is not the best trigger in the world and is no where near "match grade."  But with some "break in" (see "The Two Thousand Pellet Tune") and conservative adjustment (see "Trigger Adjustment") it can be "good enough" to start shooting accurately.

From the above description you can see that the Qb-88 makes choices in the "compromises that are air rifles" towards accuracy.  It is by modern air rifle standards a moderate powered air rifle.  Mine shoots a "real" 8 grain (weight, 1 pound = 7000 grains) pellet at about 600 ft/sec. (American advertising says a wildly exaggerated 850 ft/sec and my factory manual says a very conservative 150 m/sec = 490 ft/sec.) By the way most very expensive (>$1000) Olympic air rifles shoot right in the 550 to 600 ft/sec range for accuracy at 10 meters.

And, of course, it is reasonably priced - this is why you bought this air rifle - as there are better air rifles "out there" they just cost more - some times a lot more! At the time of this writing (Dec '99) I think that the Qb-88 is the best spring powered air rifle available for under $100.
 

Loading the Rifle with Safety

The Qb-88 is a "Direct Loading" type of air rifle.  That means that you put the pellet directly into the barrel.  Well to do this in a rifle that isn't a breakbarrel the spring and piston have to be retracted out of the way so you can get to the breach end of the barrel.  All fine and good except that in this arrangement there is the possibility that spring and piston can snap shut on your finger while you are putting the pellet into the barrel - a "Bear Trap" accident. The Qb-88 is equip with an "Anti Bear Trap" device - Make Sure That it is Working!  It is the little pointy thing that sticks up in the bottom of the chamber when you pull the cocking lever back. As you cock the rifle you should hear the "click" "click" of this pointy ratchet as it moves over some slots on the bottom of the compression tube (that silver tube that is moving when you cock the rifle.) At any point in the cocking cycle you should be able to gently allow the cocking lever to move forward and it should catch on the "anti bear trap" and stop.  When you have fully cocked the rifle the cocking lever should not move forward very far until you have released the "anti bear trap" by pushing the red button (mine is red) on the bottom of the stock. If this is not working - Fix it! or Get it fixed!  That is a powerful spring and nothing to fool around with (this is also true when you disassemble the rifle.)

There is also a safety (you can just see the top of it on the top of the stock on the right side just above the trigger when you open the cocking lever) that is suppose to prevent the trigger from being pulled while the rifle is being cocked.

Both of these "safeties" are there to protect you they should be working.  And I wouldn't rely on them. When you cock the rifle don't have your finger any where near the trigger.  And when you load the rifle place your arm or some part of your body between the cocking lever and its closed position - Just in case! As always "Better Safe than Sorry."

(And if you have to be told, "don't point the rifle at anything that you don't want to destroy, kill, or at least put a hole in" put it back in its box and go do something else!)

The Two Thousand Pellet Tune.

The easiest way to tune up the Qb-88 is to shoot it.  It like most spring piston air rifles the  Qb-88 will "wear in" with use (it will then begin to "wear out" but given the quality of the construction I think that "wearing out" will take a long time - I have over 10,000 pellet through my "high time" Qb-88 and I think that it is still "wearing in.")  Metal parts that rub against one another will smooth out those rubbing surfaces. There are many ways to take the rifle apart and smooth and polish some of the metal surfaces that will make the rifle operate more smoothly - but just shooting it will, with time, accomplish most of the same thing.

Two Thousand pellets is sort of an arbitrary number - you will begin to feel some of the "grittiness" go away with the first 100 shots. The compression tube is wearing on the inside of the receiver where punching out the metal has left a sharp edge - this goes pretty fast.  The piston seal - leather or synthetic (see "Converting to a Synthetic Seal") will begin to polish the inside of the compression tube - this takes time. And the parts of the trigger will start to smooth out - this also takes time.

The first thing that you should see is a drop off in power along with a drop off in noise and smoke. You might think that all the power for the Qb-88 to propel the pellet down the barrel comes from the spring - this is only partly true.  Some of the power comes from burning oil that should be present in a very small amount right ahead of the piston.  The Cardew's in England (authors of "the Airgun from Trigger to Target") did an experiment where they fired a high powered air rifle (for their time) in pure Nitrogen. The result was that the oil could not burn and the power fell by half.  When you start out with your Qb-88 there will be extra oil in the chamber and you will get a lot of combustion - the pellet (if it is light) may approach that 850 ft/sec and there will be a fairly loud bang and some smoke with each shot.  This is usually called "dieseling" and is hard on the piston seal and spring.  The Qb-88 is "overbuilt" and no real damage is done if this isn't continued for too long. For those that think "power is everything" you can probably continue to do this by adding a drop of oil to the chamber - through the little hole that the air comes out called the transfer port - every 10 shots or so.  You will probably have to replace the mainspring and piston seal after a thousand shots or so, but you could do it.  The reason that you might not want to (besides the maintenance) is that these dieseling shots are inconsistent (the velocity varies) and are probably hitting all over your target.  If you don't add oil through the transfer port after a while the rifle will settle down and begin becoming consistent at around the 600 ft/sec speed (It varies with manufacturing tolerances - I have 3 Qb-88's that shoot 545, 585, and 605 fps when they settled down.)  After about 500 shots you may want to add some oil to the mainspring.  "Add oil to the Mainspring?"   Yes, the oil (just a few drops) can be dropped on the mainspring - on the part that is visible under the cocking lever when the rifle is cocked.  The oil wont stay on the mainspring, but will be sprayed on the chamber walls when the gun is "fired" this will lubricate the mainspring where it touches the walls and it will find its way to the back of the piston seal - to eventually work its way forward and refuel the combustion process (that is the theory anyway.)   So the first couple of shots will be "all over the place" because of dieseling.  Then they will start to "group" but the next 100 or so will still be scattering as things wear in and settle down. You may begin to see what the Qb-88 is capable of - with those pellets. (An odd phenomena may occur in this period you may get two good groups - usually one about 2:00 o'clock from the other - I've seen this happen and the Chrony tells why - every other shot is about 50 feet/sec higher than the one that preceded it - again it is a matter of combustion.) After a lot of shooting (I won't say two thousand pellets again) the Qb-88 should be smooth and consistent - with a good pellet it will deliver its best accuracy.

The First Improvement Better Pellets

For the first 100 shots or so I don't think that it matters what kind of pellets you are using even the cheap Chinese pellets that you may have bought with your rifle. (Please note here that today (Dec '99) there are two kinds of Chinese pellets available those that cost about $8 for 2,000 and those that cost about $8 for 500. The first are not very accurate in any rifle and the second are very accurate in some rifles)  After your Qb-88 begins to settle down and your groups become better (greater than 200 shots) it is time to experiment with pellets.  It is a fact (ask any experienced adult air gun shooter) that some air rifles "like" some pellets a lot better than other pellets. In accuracy the "right" pellet makes a big difference.  I can take one of my Qb-88's and with its preferred pellet shoot 1/4" groups (size of the hole for a 5 shot group) at 10 meters - change pellets and with me doing exactly the same thing the pellets will be lucky to stay in the black (about a 1 inch circle.)
You will see the same thing if you experiment! One of the best pellets that I have found for the Qb-88 is the "Crosman Premier Light" (CPL) (in .177 it comes in two weights 7.9 grains and 10.5 grains. Light = 7.9g) This pellet is hard to find and you usually have to mail order it.  It will cost about $15 for a box (delivered) that is the bad news - the good news is that there are about 1250 pellets in a box (.177) so the price per pellet isn't too bad.  These pellets look exactly like the Crosman Copperhead round head that you can get at K-mart (etc.) for less $. Get the "Copperheads" first and see how they group for you. And get the "Premiers" there should be an improvement.  (the Copperheads are actually smaller in diameter so that they will always load in the semi auto pistols (actually revolvers) that Crosman makes and their tolerances are not as tight.)  The "Premiers" are made for competitors in Field Target trials and are "serious" pellets.  Another pellet to try is the Daisy "Max speed match" these are flat heads and just might work for you (available K-mart etc.) And there are a lot of others "out there" - your particular rifle may like one of the others - but the CPL are a good place to start your hunt for accuracy.

Trigger Adjustment

The QB-88 has a "two stage adjustable trigger."  Well sort of. But it is not a "real" two stage trigger so be careful in your adjustment of the one screw! (I have a hole in the ceiling of my garage from learning this lesson and it could have been much worse - so read carefully before you start "adjusting" your adjustable trigger.)

First how does a trigger work. All mechanical triggers work by sliding two pieces of metal until one can slip past the other. The simplest example I can think of would be to put a pin in front of your piston.  Then as you slowly withdraw the pin (two pieces of metal slide on one another) until it is finally out of the way and the piston slides forward.  In order to make it easier and a little more precise there are usually one or two extra levers involved in a trigger.  But the principal is still the same, two pieces of metal somewhere slide on each other until the piston is released.

The trigger in the Qb-88 is the same one that Gamo chose for their Hunter series (220, 440, 880) and that Theoben chose for one of their air rifles
 

Standard Rapid Trigger
15 TRIGGER ASSEMBLY
15a 1" TRIGGER PIN
15b CIRCLIPS x 4
15c TRIGGER BODY
15d SEAR
15e STRUT
15f TRIGGER PULL
15g SAFETY CATCH
15h SEAR PIN
15j LONG TRIGGER PULL PIN
15k SHORT TRIGGER PULL PIN
15l FAT TRIGGER PULL PIN
15m SEAR SPRING
15n STRUT SPRING
15p SAFETY SPRING
(Illustration duplicated from Theoben's web site at http://www.theoben.co.uk/r7_trigger.html)

A two stage trigger has two distinct stages - the trigger moves easily for a while and then there is a definite change to a slightly harder pull and the gun goes off.

A "real" two stage trigger moves the sliding pieces of metal with that first easy stage.  It is an additional safety feature.  There is a lot of overlap on the sliding metal pieces so if the rifle is bumped or dropped there is still a lot of metal to metal contact to prevent the piston from going forward without the trigger being pulled.  All most all of this overlap is taken out with the first stage. Once the first stage is "taken up" (i.e. you get to the increase in pressure) the mechanism is balanced on a "knife edge" and just a little more pressure will shoot the gun.  This is safe and effective trigger (but it is not a Qb-88 trigger!)

The Qb-88 trigger is NOT! a "real" two stage trigger - it feels like one but it isn't!  When you "take up" the first stage of the Qb-88 trigger all you have done is move the trigger against a spring - nothing else. It then contacts the lever that will move the sliding metal pieces this is the "second" stage you feel.  You then begin to slide these pieces and when one gets out of the others way the gun goes off.  You want some travel in this second stage! If you set it on a "knife edge" (as I did) It will feel like a very good "two stage" trigger - but in fact it is unsafe!  The slightest bump - even though your finger is no where near the trigger - will cause the gun to go off. And even if that doesn't happen after enough wear the edge will round off and the gun will go off after it is cocked (thus the hole in my ceiling.) I would make sure that I had at least 1/4" of trigger travel in the "second" stage.

So what you are adjusting by turning the single screw is the overlap of the two metal pieces that release your trigger. Turning the screw in (right hand screw) reduces this overlap and shortens the length of your "second" stage.  Backing the screw out increases the overlap (and safety) and lengthens your second stage.  This is the only adjustment on this "adjustable" trigger.  I would say again at least 1/4" of trigger travel in the second stage is required as a minimum.  If you adjust it to be like a match trigger - It is dangerous!

The trigger should be smooth. If it isn't - remember the "Two thousand pellet tune." it will work in.  Or you might disassemble it (using Theobens diagram and instructions) and polish and lubricate it to make it smooth. Again be careful and don't round off the sharp edge that keeps the trigger from releasing. The easiest thing to do is add a little oil and just shoot it - it will smooth out.

I don't think that anyone can make this a great trigger without making it dangerous.  Just my opinion.  You can learn to shoot well with this trigger however.
 

Mounting a Scope

Scoping the QB-88 is not as easy as it may at first appear.

And first let me suggest that a peep (aperture) sight works well with the Qb-88 I used the Beeman (it is actually made by Williams) aperture sight (#5822) on my Qb-88 for a while and thought that it was pretty darned good.  It is a little expensive (about $40) and some of the cheaper sights by Daisy or Crosman may work (I don't know) and of course you can transfer it to another rifle later (mine currently resides on my Supermax 1000.)  For close range target work the aperture sight may be all you need and it just simply clamps on to the dovetail rails. If it will not adjust low enough - which is possible you can glue something on to the top of your front sight.  I glued a piece of tubing on the top of mine to give me "Olympic" type sight picture.

OK, but I want a scope - so what's the problem.  Well actually there are three that I can think of right away.  Getting the right scope.  Not covering the loading port so you can still get a pellet in the rifle.  And getting the scope to stay put.  And I haven't found the "perfect" solution to all of these problems yet.  But I'll tell you what I know.

The right scope:  I started with a cheap .22 scope that I bought on sale mounted with the least expensive Tasco rings. It looked good! The Qb-88's best range for shooting targets is from say 5 to 30 yards.  I was shooting mostly at 10 yards and at this range the target was definitely out of focus and my groups were terrible compared to what I was getting with the aperture sight. I had to load the pellets with a pair of needle nosed pliers. I didn't vibrate the scope apart - but that probably would have been next.  I needed an "Airgun" scope with an Adjustable Objective. Next time you are in your "scope store" look at the scopes there - some will have yards marked on the big end.  The "big" lens is the "Objective" and by moving it (turning the adjustment) you can focus the scope to different distances. Most "fixed objective" rifle scopes are focused at 50 to 100 yards and at 10 yards are out of focus.  This is bad enough but there is another factor called parallax.  If I set my rifle with the cheap .22 scope in a vise and put the crosshairs at the center of the target then just moved my head just a little bit, the crosshairs position on the target would move - no wonder my groups were lousy.  Air guns shoot at shorter ranges so an "Airgun" scope with Adjustable Objective = AO will usually focus down to 10 yards (some will go as low as 5 yards) (Rifle scopes with AO may only focus down to 30 yards.) Scopes are usually designate by numbers the first is the magnification (or range of magnification for a "zoom" scope) then there is a X and the size of the Objective Lens in mm. Then it will say AO if it has and adjustable objective. A good low priced air gun scope at this time is the Bushnell "Sportview Rimfire/Airgun" scope model # 790004 which is a 4X32AO and the Model #790039 3-9X32AO (it is a 3 to 9 power zoom and doesn't cost much more than the 4 power so is usually the one people buy.)  My other choice (besides the 3-9X32AO) and the one I have on all my Qb-88's at the moment is the Leapers 6X40AO mini scope (Note the AO! this one seems hard to find at the moment (Dec '99) and may be being replaced with a better model)

The next problem Qb-88 has a short distance between the loading port and the dovetails where the scope mounts. When a Bushnell "Airgun" 3-9X32AO scope is properly mounted (so you can see through it properly - with your head in a comfortable place on the stock you look through the scope and see a clear target with light all around it. If you move your head too far forward there is a dark area around the target - the same if you move your head too far back.  The short distance that you are seeing the whole picture is where you want the scope to be.) In this position the big end of the scope will partially block the loading port.  I used a high mount to make it possible (not easy) to load the pellets with my fingers as a compromise to use this scope (we'll get to mounts soon, but you should know that they usually come in "medium" and "high" - high will mount the centerline of the scope higher off the receiver.)  This is the reason that my current choice for my Qb-88's is the Leapers 6X40AO mini scope.  This compact scope is small and when mounted as far back as it will go on the receiver easily clears the loading port.  This scope also requires the high mounts because of the 40 mm Objective lens.  The problem with this scope is that even as far back as it will go I have to lean my head a little more forward than I would like to see the whole picture. It is not too bad and the best compromise that I have found so far (it is "good enough.")  There may be a more ideal scope "out there" at a reasonable price - I haven't found it yet.

The final problem - getting the scope to stay put. When you shoot your Qb-88 (or any spring-piston air gun) when you release the piston the spring pushes on the piston and also the rifle and you feel the normal recoil that you would feel shooting any gun (just a little stronger than you might expect considering the power.) I actually like this part as it lets me know that I am "shooting" something (I now have some "recoilless" air guns and while they are more accurate - they are just not as much "fun.")  Any normal scope and mounts would have no trouble with this recoil.  However, when the piston comes to the end of the compression chamber it smashes into the rifle with a hammer blow.  You don't notice this second recoil as it is away from your and really just stops the movement started by the first recoil,  But to the scope this is the same as hitting the rifle with a hammer it wants to slip - backward - to come off the rear of the air rifle; and the internal parts of the scope if they aren't braced for this will simply come apart (this is the other reason that you want an "Airgun" scope.)  Cheap aluminum rings can't grip the scope or the dovetails with enough force to prevent the scope sliding off the rifle.  Two sets of rings that I have used successfully are the Millet .22 cal high (TP00005) which are all steel with quality set screws that can really get a grip; and the Beeman 5030H (again high) which are aluminum but have two set screw to increase the grip.  Both are more expensive ($20 to $35) depending on where you purchase, but they are the solution that I have come up with.  And when you mount them clean any oil off of the mount where it touches the dovetail and the dovetail to give them every chance not to slip. This is a standard air gun problem and if you buy the Beeman mount you will notice that the rear mount has a "roll pin" that sticks out the bottom.  For the Qb-88 you just push that up into the mount out of the way - but for a more powerful gun there will be holes drilled into the scope rail that this pin will fit into to keep the scope from sliding backwards.

And once you have gone through all this to get the scope on the rifle you still have to get it sighted in, but that is the same for any rifle so you can learn how to do that elsewhere.

I think that a scope is definitely a worthwhile addition to a Qb-88 but it isn't as easy as it looked when I first started - and it isn't perfect yet.  These are just the solutions that I have come up with so far.

Converting to a Synthetic Seal

All of my Qb-88's came with leather piston seals even though I bought them years apart and the last two were advertised to have synthetic seals.  The "piston seal" is the flexible part that goes on the front of the piston and makes an air tight seal to compress the air behind the pellet.  How can you tell if yours is leather or synthetic?  Well you can take the rifle apart and it is obvious. Or you can shine a strong light into the transfer port (little hole the air comes out of) when the rifle is cocked and the loading port is open.  If the material at the other end of this hole is a clear yellow color it is synthetic.  If what you see is metal - the edge of a screw and a silver washer it is leather.

What is the big deal? Really nothing.  I have converted two of my Qb-88's to synthetic and left my original leather they all work equally well.  I got a slight power increase with the conversion - but really it is probably not worth the trouble.  It does change how you maintain the gun.  The leather seal will need more oil to stay flexible (the synthetic doesn't need oil for that reason - it still needs some to burn.) If you should (for reasons of your own) decide to polish the inside of the compression chamber -if you have a leather seal your power will increase - with a synthetic it will decrease (reason = less oil to burn.)

When I started experimenting with my Qb-88's I wanted to increase the power. I tried a lot of the usual things to do this - stronger springs (depends on the spring but most make less power with a big increase in recoil so accuracy suffers - not worth the trouble,)  increasing and decreasing the size of the transfer port (decreasing is the way to go, but it is a lot of trouble for very little gain) And I put the synthetic seal that was in my cleaning kit into one of the rifles. I made this change very simply and gained about 20 feet/sec (585 to 605 ft/sec) so I thought it was worthwhile (I did a second rifle with slightly less improvement) and I'll tell you how if you want to try it (you might also want to do this if you damage your leather seal (though I don't know how) and want to use the synthetic that comes with the cleaning kit.)

But first, my conclusions on trying to increase the power of the Qb-88 - It is really not worth the trouble.  The Qb-88 was designed to copy accurate air rifles like the (Olympic Target Rifles) and has a very short stroke (about 2") on a relatively small piston (about 1".)  No matter what you do (short of a complete redesign) you are not going to get a whole lot more power out of this air rifle (go a head and try - I think that I learned a great deal from my studies and experiments.) The best way to increase the power of the Qb-88 is to save up about $130 and buy a Supermax 1000 (or whatever it is currently called) which is essentially that "redesign for power" that you would have done (Same basic design - longer stroke, larger piston, and spring to match.)

But if you want to put the synthetic seal on. Take it with you down to the hardware store and buy a washer that will fit in the space under the seal face (big washer) - you can see through the seal to find the diameter.  Buy a couple of smaller washers that will stack on top of each other to space the big washer so the seal will not touch the piston face - again you can see though the side of the seal to see how high this is and they should drop easily into the bottom opening of the seal.  Take the rifle apart. Unscrew the screw and counter sink washer on the leather seal.  Remove the leather seal and use the screw and counter sink washer to screw on the washers that you bought at the Hardware store.  Fit the synthetic seal over them and put it all back together - getting as little oil ahead of the piston as you can. Here you can put some grease behind the piston seal on the piston - it will work its way behind the seal soon enough. If you don't like the results you can put the leather seal back on.

Modifications for Accuracy

All of my Qb-88's are pretty accurate, but it takes practice to get the "right" hold and to do it the same each time.

First I have converted the "experimental" model to a synthetic seal and it is fairly consistent 595 - 615 ft/sec. Getting a consistent speed is really the goal of any internal modifications - as most Olympic Target Rifles operate in the range of 500 to 600 feet/sec and I assume that the makers of those rifles did that for a reason.

Second I am shooting quality pellets - currently Crosman Premier 7.9g seem to be the most accurate in my Qb-88's but some of the really good match pellets do as well (they just cost more.)

I have pushed a pellet through the barrels of each Qb-88 that I own and IMHO (In my humble opinion) they are pretty good barrels and they are choked for the last inch or so.  These ought to be pretty accurate air rifles at 10 meters or so - as the mechanism is more or less copied from the FWB300 without the recoilless part (and as I said, "once you get your technique right they are.")

I have found that my best hold is, rather than the artillery hold (which is light and lets the rifle move,) is to grip the Qb-88 as tightly as I can.  This leads me to believe that more weight - especially around the barrel might help.  So I began to experiment.

I had a Vortek Accurizer muzzle weight available and tried that - there was an improvement due to the weight.  There didn't seem to be much difference due to the micrometer adjustments that can me made with this unit. And with the unit on the rifle it shot low.  I thought that perhaps the pellets were hitting the brake - though I could see no evidence of this so I tried rotating the brake - still shot low - but more accurately with less sensitivity to hold.

So I consulted some of the reference books that I have looking for a heavy tube that was cheap and easy to get to  use as a barrel shroud. I discovered that, if I could find some, copper pipe (not tubing - pipe that you could thread)  would be ideal. I wanted SPS (Standard Pipe Size) 1/2 inch which is .620 for an inside diameter (the barrel is 15mm,  I think, so about  .593 in as I measure it) and .840 for an outside diameter (haven't got a clue where the 1/2 inch comes in - probably from the Romans) - It should weigh about 1 lb. per ft.  However it seems that no one makes  Copper pipe any more (just tubing) though I'm still on the lookout.  I did get a length of black iron pipe (not as good looking or heavy and with a seam on the inside that you need to clean out) but it works. And I tried a length of Thick copper tubing that is used to slip over 1/2 inch tubing to repair a split - made by Prairie Home Products and sold by  Home Depot. I slid this on behind the muzzle brake and fastening it down with the stock. More weight has the rifle shooting low again but has once again improved the accuracy and decreased sensitivity to how you hold the rifle.

Why does it shoot low with the additional weight? Well you might think that the weight is bending the barrel down.  I  don't think that this is true - but I haven't disproved it yet.  Try this experiment with your Qb-88: leave the sights the  same and shoot a heavier pellet.  The heavier pellet will be slower and you would expect it to hit lower on the target.  My experience says it will hit higher.  Why? I think that when the rifle recoils (the first recoil) it starts to climb and  when the piston hits the end of its travel this almost but not quite stops this climb. The pellet that stays in the barrel longer will come out higher on the target.  I can't prove this either (If someone has a high speed camera and wants to see if this is true I would be most interested.)  If it is true - then I think that the added barrel weight limits the recoil  and therefore this climb and the rifle shoots low.

These experiments have convinced me that the way to better accuracy if you have a Qb -88 is get it as smooth and consistent as you can,  experiment with different pellets to find the one it "likes best," and add some weight - first to the barrel.  A piece of black iron or copper pipe drilled for set screws at each end or a muzzle brake that you turn out of a piece of steel - is a good start.  I'm not recommending that you buy a $50 muzzle brake for a $90 rifle - unless you are that kind of person. A heavy magnet might be a good start. Then I'm going to try adding weight to the stock - again cheaply by drilling holes in it and filling those holes with epoxy and used (read flattened) pellets.

Conclusion

Well that is where it stands so far with my knowledge of the Qb-88.  Remember "Your mileage may vary" this is what worked for me on the rifles that I have. I hope I can give you a running start on enjoying this fine (specially at the price) air rifle.


NOTE:
Acurizing the TF(Qb)-88  The secret = weight.

This is the latest (Feb'00) Accuracy configuration for my Qb-88

First you should know that My Qb-88's are pretty accurate, but it takes practice to get the "right" hold.

I have converted the "experimental" model to a synthetic seal and it is fairly consistent 595 - 615 ft/sec.

And I am shooting quality pellets - currently Crosman Premier 7.9g seem to be the most accurate.

I have pushed a pellet through the barrels of each Qb-88 that I have, and IMHO they are pretty good barrels and they are choked for the last inch or so.  These ought to be pretty accurate air rifles at 10 meters or so - as the mechanism (bore & stroke) is more or less copied from the FWB300 without the recoilless part (and as I said, "once you get your technique right they are.")

I have found that my best hold is, rather than the artillery hold which is a light hold, is to grip the Qb-88 as tightly as I can.  This lead me to believe that more weight - especially around the barrel might help.  So I began to experiment.  My experiments have convinced me that additional weight on the barrel will make the Qb-88 a little more accurate with less sensitivity to hold.

But I used some pretty expensive (relative) stuff to carry out these experiments - how do I do it cheaply. Here is what I use in the latest arrangement and if you work at it I don't think it will cost you over $10.

Here is a list of materials (we have "Eagle"  and "Home Depot" as the primary Home Improvement Store in the Area and all these parts are from them:)

A length of Thick copper tubing that is used to slip over 1/2 inch tubing to repair a split - made by Prairie Home Products and sold by Home Depot (Eagle has an equivalent) its about 12" long. (about $3)

From Eagle a 1/2 X 5" Brass Nipple (that is what it is called - it is a length of brass pipe SPS (Standard Pipe Size) 1/2 inch which is .620 for an inside diameter and .840 for an outside diameter (haven't got a clue where the 1/2 inch comes in - probably from the Romans) - threaded at both ends) (it is made by "AB = Anderson Barrows part SP-56B or PB113)(about $3)

And also from Eagle a piece of thin walled brass tubing 5/8"-1Ft (.014)( Steel WorkS Part 84138 or D5) - I had this for another purpose, you might use material clipped from an aluminum can instead. ($4 or $0)

And JB Weld - a two part epoxy that I got from an Auto Parts Store and a Washer that you probably already have.

What you do:

Pull off the Qb-88's plastic front sight - I had someone hold the rifle and tapped the sight from behind using a punch and hammer - it just slides off, but it is tight.

Next loosen the front stock screw and slide the copper tube over the barrel. It will stop just short of the receiver on a slight increase in barrel diameter.  Then tighten the front stock screw.

Then I took the "brass nipple" and cut off the front threads.  I used a tubing cutter, but a hacksaw should do.  I then filed and sanded the front flat and smooth.

Now, what I did was cut a piece of the 5/8" brass tubing the length of the remaining barrel (between the part covered by the copper tube and the reduction in diameter for the front sight = about 3.") Then since it is just a little too large to go in the "brass nipple" I cut a slot the length of the tube about 1/8" in wide. I slipped this tube partly over the barrel and partly into the "nipple" then forced the "nipple" on to the barrel. Since this was a tight fit and since the "springier recoil" will make this part slide to the rear - which it can't do because it is blocked by the copper tube - I didn't feel the need to use any other form of attachment.  If it starts coming loose I may drill and tap it for set screws, but for now it is holding.

Then I glued (using the JB Weld - you could try any epoxy glue) the washer on to the front of the "nipple" just to make it look right.  There is a big enough hole in the washer so I wasn't worried about the pellets hitting it.

Your done.  I was going to paint it flat black, but it looks pretty good in copper and brass (I had a brass washer) so I just used some Brasso on it and left it.

It adds about the right amount of weight and I think enhances the accuracy of my Qb-88 at least it is less hold sensitive. I think because the stock is in contact with the barrel I might get some undesirable effects so I may carve out the stock to get a "free floating" barrel next.  But so far - except for some brass and copper scratches on your barrel - nothing has been done that isn't reversible if you don't like it and the cost to try this is about $10 or less. Try it you might like it.

At this point my experimental Qb-88 that cost me about $80, has this mod $10, a Leapers 6X40AO scope $45, Millet High mounts $25, is wearing the stock with the Morgan adjustable butt pad $30, and has a military type sling $20, and swivels $10, (I don't use the sling for shooting but appearance and carrying - and the leather adds a nice smell.)  So all told I have about $220 into this one at the moment. (Interesting as my Supermax 1000 has the same scope and mounts and that's all so it is at ($150+$45+$25) $220 also.) Oh well the sling, butt pad and copper and brass barrel, "Do Look Good" (IMHO.)

Just though I would share these ideas.

Jim P.

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Close-up Photos

Photo 1.    QB-88 action taken out of the stock; cocking lever and link.
Photo 2.    The receiver tube is made out of seamless steel tubing, highly polished inside out.

Photo 3.  The 20stage trigger design is strickly a copy of Gamo.  The tab in the front is the manual trigger safety switch.  The length of trigger pull can be adjusted  by a small screw right behind the trigger.
Photo 4.  Compression chamber, piston, mainspring guide/stop, and trigger assembly.
The compression chamber is polished and crome-plated.  The milled teeth  on the chamber are for the breech safety ratchet.   The pressed steel piston body appears to be machined after weldding.   It was reported that the earlier production used a leather piston seal.  However, those of  recent production all have  a synthetic seal.   The rear stud is machined out of solid steel, with stamped steel spring guide.



Another note:  The production of QB-88/TF-88 is no longer at the "OEM"- Shanghai Airgun Factory.  A sub-contradtor has been manufacturing QB-88 and  a number of other models of Industry airguns  in recent years.   The noticed changes on new QB-88 include the shape of the stock.  The original ones have a flat and heavier fore stock (as shown in the image of QB-88 right under the title), while the fore stock of the  newer ones has become  tapered.


What do you do next, after you have received a new QB-88 ?

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Posted by JS on Airgun Letter Forum, August 02, 2000 at 14:24:55:

 In Reply to: My QB-88 will be here soon - what do I do next? posted by Dan D on August 02, 2000 at 13:57:28:

I'm no expert, but here's what I did. (long)

First
DO NOT DRY FIRE IT.
Then go to the URL I list below and READ READ READ!
DO NOT DRY FIRE IT.
Look at the manual....don't be frustrated, it isn't very readable. The literal translation from Chinese is fun to laugh at though.
DO NOT DRY FIRE IT.
Check the gun for obvious defects.
Check the stock screws for tightness....they'll loosen at first. Keep them snug.
DO NOT DRY FIRE IT.
I didn't clean mine...just wiped it down. The bore shot well from the box so I left it alone. Some like to run patches through first though.
DO NOT DRY FIRE IT.
Prepare a safe backstop and get your pellets ready.
When you are ready to fire a pellet: Cock the gun.
DO NOT DRY FIRE IT.
Now look inside the open chamber and make sure the anti-beartrap catch is sticking up to catch the piston tube in case of an accident. I always look at this when loading to make certain...I like my fingers.
DO NOT DRY FIRE IT.
Load a pellet.
With your right hand on the cocking lever, push the red release button under the forearm with your left hand...this will lower the anti-beartrap catch.
Watch how all of this works so you'll know when it's functioning right or not.
Move the cocking arm forward to close the breech.
The manual says the safety automatically engages...but mine never has. I never rely on manual safeties anyway....I just make certain I am the "safety".
Raise the gun, aim and pull the trigger.

It takes 100 shots or so to calm the dieseling down. So it'll be loud at first. After a couple hundred shots, things begin to settle in. After 500 or so, the trigger will get really nice.
There are ways to speed this up...but just shooting it will do the same thing.
Resist the urge to oil everything...especially the chamber.
Mine has just under 10,000 shots now. I keep the linkage oiled, but have yet to lube the chamber. So far, it's not been needed. These things come fairly soaked inside.
You'll probably have a leather seal..no matter what the vendor said. With the breech open, look into the opening, shine a light into the small air hole in the breech face....if you see a metal screw and washer, it's probably a leather seal...if you see sort of yellowish material it;s a synthetic seal. You can buy replacements, but the leather will give good service with proper care and no over-oiling.

I'm on my way in a couple hours to shoot my QB-88 out in the country. See what it can do against the starling population today! :-)
Mine loves RWS Meisters and R10 pellets in 8.3 grains.
I got mine from SouthSummit also....and have been elated with it. Just wish we could get them in .22 also.

hth, Jack

btw- did I mention DO NOT DRY FIRE IT :-)