I'm one of many happy owners of the QB-78 rifle and this is another
modification of this wonderful piece of shooting equipment.
The stock was done entirely from the existing factory stock, by removing
unnecessary wood. This rifle deserves the best look possible and I
think we
(Uncle Gary and I) are getting
close to it. Thank you for publishing this picture of my work on your website!
Regards,
Tom Zablocki
Uncle Gary's comments:
Tom is being very kind, but I don't deserve any
of the credit here, this design is entirely his work. I simply told him
how much I liked his
stock design, and I would see if we could get it up on a good website
that other QB owners frequented. I have re-done my stock to Tom's design,
and it turned out very well, much more pleasing than the factory QB stock.
I believe any QB owner could also easily redo their own stock like this;
I only used a set of wood rasps, a Dremel tool, and a finish sander to
do mine. There is a bit of hand-sanding necessary to form the pistol grip
and schnauble tip on the forend, but it is well worth the extra effort.
God Bless!
Unc
The best looking stock for QB-78
Tom Anderson's Customized QB-78, photo from the web site of Air Gun
Fun ....For ALL!
(http://airgun-fun.tripod.com/airgunfun/id2.html)
Custom stock for QB-78 by Mike Abernathy (http://www.customwerksairgunning.com/)
April 22 2002 at 10:43 PM
Posted by Bill xxxV (Login Billxxxv)
from IP address 24.26.93.68
Here are a couple of pictures showing what can be done with a QB 78. The thumbhole stock was hand carved from a blank produced by Don Main, and it has 11 hand rubbed coats of Tru Oil finish with a Pachmeyer (sp?) butt pad. The scope is a Swift 6-18x44 AO from Marty at SS. The bulk adapter is a Mazibulk unit with a built-in pressure guage. The barrel band and muzzle break are made by CJ Pitts. The internals (valve body reshaping, piercing pin reshaping, valve return spring shortening, porting, polishing, bolt probe, additional barrel retaining setscrew, trigger return spring retaining bolt shortening, and sear honing work) have been tweaked and it shoots the following strings:
Shot...Velocity..Energy..Dev From
#.........(fps).....ft.-lbs..Ave
Vel
1.........702.5....11.51...1.93
2.........700.2....11.43...4.23
3.........702.3....11.50...2.13
4.........708.5....11.71...4.07
5.........705.6....11.61...1.17
6.........701.4....11.47...3.03
7.........704.0....11.56...0.43
8.........713.1....11.86...8.67
9.........704.8....11.58...0.37
10.......701.9....11.49...2.53
Pellet Name: CP Heavy.
Pellet Wt in Grains: 10.5
Airgun: QB 78
Temp: 85 Degrees
Average Velocity =704.4 Feet/Second
Average Deviation=2.9 Feet/Second
Standard Deviation=3.9 Feet/Second
Highest Velocity =713.1 Feet/Second
Lowest Velocity =700.2 Feet/Second
Extreme Spread= 12.9 Feet/Second
Average Energy =11.57 Ft.-Lbs.
Standard Deviation=0.127717201 Ft.-Lbs.
Highest Energy =11.86 Ft.-Lbs.
Lowest Energy = 11.43 Ft.-Lbs.
Extreme Spread= 0.43 Ft.-Lbs.
Thanx!
The tweakster!
What are QB-77, 78 and 22 ?
Industry Brand QB-78 is a .177 caliber, CO2 powered air rifle. It is a copy Crosman 167, made and assembled by Shanghai Airgun Factory in China. QB-77 is the same as QB78, except that it is assembled and inspected by the experienced airgunsmiths of MAC-1 in America. QB-22 is a .22 caliber, and a copy of the Crosman 160.
REMOTE_ADDR: 152.163.205.27
REMOTE_HOST: spider-ta038.proxy.aol.com
Posted by LOU
V.K. on May 04, 2000 at 13:17:58:
The Crosman 160 that I ordered from the
CMP just arrived. It was packaged in one of the most sturdy packing boxes
I have seen. Inside of the box was the same type of egg carton foam padding
as is found in most high quality hard shell gun cases. Padded between two
layers of this foam, I found a paper,plastic, and, aluminum foil rust inhibiting
sealed package. It contained the rifle, which is absolutely new, and, unfired.
It looks as though the package has been roughly handled, as the stock has
several pressure dents, from harsh handling. After pulling the action from
the stock, I adjusted the trigger,( a very good one, BTW ), ran a tight
patch through the pipe, and wiped the exterior metal with Rem Oil. The
patch came out of the pipe as clean as it went in.
I then opened the gas tube and removed the old
copper colored powerlets, replaced them with fresh ones, after dripping
a couple of drops of SAE 30 N/D oil onto the piercing pin in the bottom
of the cylinder. The rifle holds gas pressure.
Now, for some shooting.
I fired some Gamo 5.5MM match wadcutters, which
all went into one small hole, from the sandbags. CP's did not perform quite
so well at the 21 yards that I was using for testing, in my back yard.
I then, brought out my Chinese 78-.22, which proceeded to out shoot the
Crosman by a small margin. The Chinese stock is a more dense, nondescript,
bland oriental hardwood, that has been stained and varnished with an old
mop. The Crosman is stocked in a VERY plain, and, open grained piece of
American black walnut.
As a collectible, the Crosman is worth more money
than the QB 78, but, IMHO, the Chinese offering is at least as good a shooter,
and, at just over 50% of the price of the Crosman. In addition, the Crosman
is equipped with a very fine dioptor sight, whereas, the Chinaman has a
plain vanilla Patridge sight, and, is grooved for scope mounting, which,
IMHO, makes for a better setup for most 'users'. I know that Jerry Rhodes
will argue with me on this one, but, with my antique eyes, a scope works
a bit better.
I am NOT sorry that I bought the 160. I am also
quite pleased with my QB78's as low powered plinkers.
While typing this, I had a visit, thanks to one
of my neighbors, from one of Grand Rapids ' finest ', who informed me that
the discharge of firearms within the city limits is unlawful, and, if he
had to come out again on this kind of complaint, he would stop off to get
a confiscation warrant from one of the local judges, to pick up every gun
in my house. Nice neighbor,huh ?
REMOTE_ADDR: 63.14.106.138
REMOTE_HOST: 2Cust138.tnt2.san-antonio2.tx.da.uu.net
Posted by Boxlock on May 16, 2000 at 21:52:38:
As some of you probably know Charles Mistretta recently posted a challenge for someone to evaluate the QB-78 against the original Crosman-160's and the Tim McMurry of Mac-1 Airguns fame tuned versions of the Clone. Since I owned an original Crosman-160 and the .22 version of the QB tuned by Larry Durham who helped develop Tim's modifications, I offered to take the Challenge and post a review of the QB-78 on the board. The biggest limitation on the relevance of the data collected is the fact that the QB-78 is .177cal and both the Crosman-160 and my Custom QB-22 are both .22cal. This will have some bearing on results since the pellets are not of equivalent weight, thus the velocity and foot pounds of energy calculated will not be directly comparable between caliber's.
Initial testing took place Sunday May 14, 2000 between 09:30am and 14:00pm. My friend and experienced fellow airguner Abraham Garcia was on hand to verify the assist with the chronographing and verify the accuracy data. He also graciously donated a very large sample of .177cal pellets from his personal stock to supplement my limited selection of .177cal pellets. Due to a recent cold front moving through the area the ambient temperature at the range was an unseasonably cool 66°F with a barometric pressure of 30.1"hg and relative humidity of 49% winds where from the NE at 13mph with gusts up to 26mph. Unfortunately not the ideal conditions for accuracy testing of CO2 powered Airguns. Chronograph used was my reconditioned Chrony F-1 placed at a distance of ten feet from the muzzle of the gun.
First gun up to bat was the QB-78. The gun arrived in original packaging and brand new with the factory manual. It was not charged with CO2 prior to shipping. The gun was in excellent condition with nice bluing and two slight impressions on the stock that really had to be looked for, to be seen. The gun appeared identical to my custom QB in appearance, caliber was obviously different and one of the first things I noticed was the receiver plug at the rear was slightly loose and wiggled. This however was a mostly cosmetic glitch and should not affect performance, a few small burrs where removed from the loading port area with a pencil eraser. The gun was initially charged with two CO2 Powerlets and two drops of pelgun oil. Staight from the box the trigger weighed in at over six pounds with a long creepy pull, Yuck! I received Charles' permission to adjust the trigger and got it breaking crisply but could not adjust the pull weight below four pounds by simply using the screw adjustments on the back of the trigger assembly. This is the first and only Crosman style adjustable trigger that I've not been able to easily adjust to below 1lb. A second attempt to adjust the trigger after I got home and could sit down and take my time with all my tools readily available revealed a burr on the trigger return spring that was catching the threads of the housing for the adjustment screw. A quick snip with a tiny pair of wire cutters quickly solved the problem and the trigger was easily adjusted to just below one pound pull weight with a short crisp let-off, and virtually no overtravel. Bolt felt rough and tended to bind a little on opening from time to time, but this will smooth as gun breaks in. Factory sights where open buckhorn style and sadly inadequate, with no rear windage adjustment, but did move laterally with the slightest nudge making them very difficult to zero. Elevation adjustment is accomplished by sliding a graduated frame of indexing notches forward under rear sight blade. On the lowest setting the gun still shot almost three inches high. Rear sight was removed and a Bushnell Sportview scope was mounted using Tasco rings. See the following table for results of the pellets tested.
Name Wt. avg. fps. Maximum spread fps. Standard Deviation FPE
Crosman Premier Lights 7.9gr 630.5 11 2.70 6.98
H&N Match 8.09gr 612.2 12 2.76 6.74
RWS Superdome 7.7gr 594.3 18 4.33 6.04
Beeman Silver Arrow 11.5gr 519.0 22 5.90 6.88
Meisterkugeln 8.3gr 584.7 20 4.62 6.30
Marksman FTS 8.6gr 582.1 16 3.92 6.47
Accuracy was initially disappointing. Best accuracy for the QB-78 was obtained with .177cal Marksman FTS pellets, but given the wind almost any of the pellets tested could possibly beat them out for first place on a calm day. I strongly feel the wind conditions contributed to this little guns poor groups. All groups where shot at 35yards. Five, five round groups on a single target where measured outside edge to outside edge at the groups widest point with a stainless steel Dillon caliper to determine the groups raw size. The pellet diameter .177 was then subtracted to determine the size of the group center to center. I wish to qualify results by stating that I simply sat down to the bench and quickly shot five, five shot groups on a single target. This was not the best of a series of targets, nor does it represent a limit of the guns full potential. No allowance was made for a bad group or poor shooting conditions. The results where taken as is. I believe testing this way gives a better representation of the kind of accuracy that one can expect strait from the box then day in, day out. The five groups from largest to smallest measured 2.70"raw, 2.52ctc; 2.36"raw, 2.18"ctc; 1.98"raw, 1.80"ctc; 1.85"raw, 1.67"ctc; 1.5"raw, 1.32"ctc; the average size of the five groups is 1.9"ctc with a maximum spread of 1.2" and a standard deviation of 1.4". I expected better, but strongly suspect the .177pellets simply weren't bucking the wind well. The number of useful shots provided given on a single fill was measured for both two standard 12g CO2 powerlets and a bulk adapter with extension tube. To determine the number of useable shots per fill I decided to measure the average velocity of the first ten shots and multiply that figure times 0.8 to give velocity at which the gun fell below 80% power. Using CP lights the average velocity of the first ten rounds on powerlets was 628fps. When multiplied times 0.8 the velocity at which the gun fell below 80% power would be 502.4fps. The gun first fell below 502.4fps using powerlets on the fifty sixth round. Bulk adapter with extension tube was added and gun was filled. The average velocity of the first ten rounds on bulk was 631fps. When multiplied times 0.8 the velocity at which the gun falls below 80% power is 504.8fps. The gun first fell below 504fps on round number eighty seven. Extended bulk then delivers (56/87) X 100 = 64.37% more shots per fill with a negligible increase in average velocity of (628/631) X 100 = 99.5246% subtracted from 100% = 0.48%. That's two thirds more usable shots per fill on bulk!
I repeated the accuracy tests for the QB-78 Monday, May 15, 2000 with more cooperative winds. Temperature remained an unseasonable 69°F barometric pressure 30.12"hg relative humidity 76% winds from the SE at 3mph with gusts to 8mph. I again measured the best five, five shot groups on a single target at 35yards using the method described above. From worst to best... 1.73"raw, 1.55"ctc; 1.59"raw, 1.42"ctc; 1.45"raw, 1.28"ctc; 1.35"raw, 1.18"ctc; 1.27"raw; 1.10"ctc; average of the five groups was 1.31"ctc with a 0.45" maximum spread and a standard deviation of 0.14".
Next gun up was the custom, bulk CO2 powered, QB-22 tuned by Larry Durham. Gun is excellent in overall fit and finish, scoped with a Bushnell Sportview 4X32mm on Tasco Rings. It's equipped with the factory barrel, re-crowned of course, trigger breaks crisply at 1.2lbs and extended tube bulk fill apparatus, but can easily be reverted to take two standard 12g CO2 powerlets. See the table below for results of various pellets tested.
Name Wt. avg. fps. Maximum spread fps. Standard Deviation FPE
Crosman Premiers 14.3gr 580.8 32 7.25 10.72
RWS Superdomes 14.5gr 631.9 15 4.35 12.86
Meisterkugeln 13.9gr 642.0 23 5.80 12.73
Beeman Silver Arrow 17.1gr 627.5 10 2.75 14.96
Beeman Kodiak 21.1gr 551.0 15 5.50 14.23
Korean Heavy Domes 29.0gr 486.3 9 3.85 15.23
The velocity/energy results during the unseasonably mild weather where disturbing for me, living in Texas as I do, where temperatures sometimes remain in the eighties most of the winter. I'm used to seeing this gun produce at least 14fpe with the lightest of pellets and over 16fpe with the heavier stuff. On hot days above 95°F, 17+fpe is easily attainable with heavy pellets. Accuracy obtained with this gun is always good for ones ego. Kodiaks came in a very close second to the RWS Superdomes for best accuracy obtained, which is questionable given a 13mph crosswind gusting up to 26mph. On a still day, their positions for best accuracy could easily be reversed. Again to represent the accuracy one can expect day in, day out, five, five-shot groups where quickly fired on a single target using RWS Superdomes, giving no allowance for a bad group or poor conditions. Groups where measured for raw group size, from edge to edge, at the group's widest point, using a Dillon Steel caliper. Then the pellet diameter of .22" was subtracted from each raw measurement to give center to center group diameter. All groups where shot at 35yds. From worst to best the groups measured 1.32"raw, 1.1"ctc; 1.15"raw, 0.93"ctc; 0.975"raw,0.755"ctc; 0.925"raw, 0.705"ctc; 0.60"raw, 0.38"ctc. The center to center measurements of these five groups averaged together to equal 0.774"ctc. with a maximum spread of 0.72" and a standard deviation of 0.19". The number of shots was measured using both powerlets and extended bulk to weigh the benefits of bulk fill. To determine the number of useable shots per fill I again measured the average velocity of the first ten shots and multiplied that figure times 0.8 to give velocity at which the gun fell below 80% power. Using RWS Superdomes average velocity for the first ten round using two fresh daisy powerlets was 628fps. When multiplied times 0.8 the velocity at which the gun fell below 80% power was 502fps. The gun first fell below this velocity on the forty eighth round. Using RWS Superdomes with a bulk adapter and extension tube the average velocity of the first ten rounds was 631fps. When multiplied times 0.8 the velocity at which the gun fell below 80% was 504fps. The gun first fell below this velocity on the 73 round. (48/73) X 100 gives a 65.75% increase in the number of useable shots per fill on bulk, with a negligible increase in velocity using the same pellets of (628/631) X 100 = 99.525% so 100 - 99.525 = 0.475%. That's still two thirds more usable shots per fill on bulk folks!
Accuracy testing on the QB-22 was also repeated Monday, May 15, 2000. The more favorable winds definitely made a difference here. Five, five-shot groups where again fired from the bench at a single target using RWS Superdomes, at 35yards with no allowance for bad groups or conditions. This time the five groups listed in order from worst to best measured 1.37"raw, 1.15"ctc; 0.79"raw, 0.57"ctc; 0.76"raw, 0.54"ctc; 0.58"raw, 0.36"ctc; 0.53"raw, 0.31"ctc. Average of the five groups was 0.59"ctc with a maximum spread of 0.84" and a standard deviation of 0.23". That last group was sub-MOA. Told you this little gun was good for the ego!
Next gun up for assessment was my original stock Crosman-160, but it being Mothers day, I promised the spousal unit I'd be home by 14:00pm, and we ran out of time, I did however follow through and test the Cr-160 the following morning Monday, May 15, 2000. See table below for results of pellets tested.
Name Wt. avg. fps. Maximum spread fps. Standard Deviation FPE
Crosman Premiers 14.3gr 579.8 2 1.6 10.68
RWS Superdomes 14.5gr 574.2 6 2.35 10.62
Meisterkugeln 13.9gr 611.2 5 3.80 11.53
Beeman Silver Arrow 17.1gr 589.3 8 2.37 13.19
Beeman Kodiak 21.1gr 522.2 11 2.44 12.78
Korean Heavy Domes 29.0gr 458.7 7 3.85 13.55
I did not have scope mounts available to fit the Crosman-160 so accuracy testing was done using S-331 target sights, all groups where shot at 35yards. Wind was much more cooperative this morning and again the groups where measured with Dillon Caliper measuring outside edge to outside edge at groups widest point to determine a raw group size .22" bore size was subtracted to obtain center to center group size. Best accuracy was obtained with RWS Superdomes and five, five shot groups on a single target where measured, and will be listed from worst to best. 1.79"raw, 1.57"ctc; 1.43"raw, 1.21"ctc; 1.27"raw, 1.05"ctc; 1.09"raw, 0.87"ctc; 1.07"raw, 0.85"ctc; Average of the five groups was 1.11"ctc. with maximum spread of 0.72" and standard deviation of 0.224". Again gun is good overall with minor loss of bluing and a few minor stock scratches. Gun is equipped with extended bulk and I opted not to take it down to test it with powerlets. Powered by bulk CO2 the average velocity for the first ten rounds of superdomes was 576.5fps, multiplied times 0.8 the velocity at which the gun would fall below 80% power would be 461.2fps. The gun did not fall below this mark until the sixty ninth shot. I had planned to compare it directly with Abraham Garcia's Crossman-160 which is not equipped with bulk fill adapter, but time constraints did not allow the comparison Sunday, the only day this gun was available.
In conclusion, results of the testing show the QB-78 to be a delightful
little plinker, this design is obviously not at it's best in .177cal, I
expect that 8-10fpe could be obtained in this caliber on a warmer day.
It would be marginal as a short range hunter at this power, the .22 would
certainly be the better choice for this application. For the sale price
of $89 this little gun represents a remarkable airgun value. The gun also
provides a platform that allows easy and inexpensive customization and
upgrades that put it in a class with airguns costing three times as much.
The gun did not prove quite as accurate as the tuned version, or the original
Crosman-160 but accuracy was certainly adequate for a gun in this price
range. Fit and finish was quite good for a Chinese airgun under $100. It's
appearance does compare favorably to other airguns and firearms in the
sub-$150 price range and looks fine in the rack between a Benjamin 392
or a Marlin-Glenfield, but it looks kind of plain between a Career-707
and a Kimber-82. It's light weight and ease of use makes it an ideal marksmanship
trainer for young shooters. The extended bulk option adds immensely to
this little guns utility, as well as adding a bit of weight forward of
the balance point making the gun hold much steadier for offhand shooting.
Factory rear sight proved inadequate but gun easily accepts a scope or
quality diopter sights. Lacking the two way recoil of a spring gun, inexpensive
scopes and mounts work fine on this little gun, and it's accuracy potential
almost demands the use of a scope. These guns seem to require a bit of
tuning to match the accuracy potential of the original Crosmans but the
absence of scope rails on the original guns gives the QB's and advantage.
If you have the choice, go for one in .22caliber.
QB78 groups at 25 yards
From: Andrew Leung (DRLEUNG) 12:45 am
went and did a group or two with the QB and man was I more than impressed!! These are outdoor groups on a benched sandbag rest using 14.3 gr premier pellets...I even threw in a Beeman R-1 for comparison (with vortek ram and tuner in the best setting). As well as an Anschutz 1808 match rifle in .22lr for a comparison group since there were a slight wind factor (thus the Anschutz didn't group one hole as it normally does).
I had to cut and tape the targets to fit the scanner bed.
Qb stock ...Beware!!!!
REMOTE_ADDR: 206.103.88.2
REMOTE_HOST: ns.lowrance.com
Posted by CJ
on June 06, 2000 at 11:19:52:
I wanted to refinish my qb78 stock.
I took it to work to work on at breaks. stripping
it was no big chore used sand paper and denatured alcohol. Doing my final
sanding I heard a POP! The butt of the stock checked a crack about 1" long
Then another and another right before my eyes. I have 4 checks the longest
being 2.5". I'm a metal guy wood is not my stongest ,So I asked a guy why
it was doing that he said that the wood must have been finished still a
little green and that the varnish seal it. When I striped it and used the
alcohol it dried out so fast that it checked. Thought I'd let you guys
know and it looks like i'm making a new stock.
CJ
Re: Qb stock ...Tip
REMOTE_ADDR: 63.165.45.44
REMOTE_HOST: 63.165.45.44
Posted by Chavez on June 06, 2000 at 12:43:49:
In Reply to: Qb stock ...Beware!!!! posted by CJ on June 06, 2000 at 11:19:52:
CJ,
I just refinished mine, I chemicaly stripped
the stock then brushed it down will denatured alcohol and while the stock
was still wet with alcohol, I washed it down with water, saturating the
wood, pat it dry, then let dry overnight. The water will not evaporate
as quick as the denatured alcohol and dry out the stock as quickly causing
it to crack. If you get another QB stock you might want to try this.
If you would like to get some of the stain out
of the wood and save yourself some sanding after doing the above, use some
bleach and work it into the wood with a toothbrush, let it set a bit, rise
with water pat dry, let dry overnight, sand and repeat the bleach process
if you want a lighter wood then finish sand it. I added a pachmayr pad
to mine to extend trigger pull and stained my stock in red mahogany, finished
with spar urethane... looks real nice.
Respectfully,
Chavez
Re: Qb stock ...Tip
REMOTE_ADDR: 206.69.151.7
REMOTE_HOST: 206.69.151.7
Posted by ProfHoff on June 06, 2000 at 23:45:11:
In Reply to: Re: Qb stock ...Tip posted by Chavez on June 06, 2000 at 12:43:49:
Don't use bleach. It leaves undesirable substances in the wood.
Instead, use 3% drugstore grade hydrogen peroxide. It decomposes to oxygen gas and water -- no deleterious residue.
Regards,
ProfHoff
P.S. Wear gloves -- your hands won't like the
effects of the peroxide.
A discussion about the economical ways of getting CO2 refills
Buy CO2 in Bulk at the fire extinquisher shops
Posted by DT Fletcher on August 21, 1999 at 04:02:27:
I have never warmed up to freezing tanks or guns:-) It is an invitation for overfilling. However, in order for liquid CO2 to pass from one tank to the other there must be a pressure difference between the two tanks. This is accomplished by pre-chilling the tank to be filled. The standard method for accomplishing this pre-chilling is to bleed some CO2 through the tank to be filled. This is achieved through the use of a T-valve that allows the gas from the main supply tank to flow through the tank to be filled. This pre-chilling only takes a few seconds.
Here is a great example: When I just recently had my 5 pound I paid very close attention to what the operator did. After attaching the T-valve he blew CO2 through the tank for maybe 5 - 6 seconds to pre-chill the tank. He then switched the T-valve and liquid CO2 entered the tank. He then weighed the tank and it came up short of 5 pounds net, so he switched the T-valve again and blew out some CO2. This second pre-chilling lowered the temperature of the 5 pound tank and thus the internal pressure was also now lowered. He switched the T-valve back and was able to load enough CO2 to completely fill the tank.
The principle at work is that when there is liquid CO2 present the internal gas pressure is strictly determined by temperature. The operator described the second pre-chilling as lowering the pressure, which of course it did, but if he was to let the tank warm up to the original temp he would no longer be able to load any additional liquid CO2 to the tank since the internal pressures of the two tanks would now be the same.
The same thing can be done when filling an airgun. Typically when the gun is decocked there is enough pressure on the exhaust valve to allow CO2 to pass through. After attaching the gun to the tank, bleed a little CO2 through the gun, turn off the tank, cock the gun and then turn on the tank full open, then close the tank. Remove and weigh gun.
The calculated 100% net fill weight for the model 116 is 18 grams of CO2 but there is no reason to put that much in. 14 to 15 grams puts you right at the beginning of the level pressure area of the CO2 dynamics curve and extremely consist shot to shot operation. I make it a habit of timing the length of pre-chilling and what the resultant net fill weight was. So far, with 15 seconds of prechill the typical net fill weight is 17-18 grams with 10 seconds of pre-chill typical net fill weight is 14-15 grams.
Economy note: This CO2 bleed pre-chilling of course eats up CO2, so the shorter the pre-chill the less wasted CO2.
Pre-chilling the gun by bleeding some CO2 through it is particulary useful when charging up the old MAC-1 QB-22 deluxe. Can't imagine putting that gun in with the ice cream bars.
Warning: if it is expected that the gun being
filled will be exposed to temperatures at or exceeding 80 degrees F then
only a 70% fill should be made.
dt fletcher
----------------------------
Posted by Bill
B. on August 21, 1999 at 14:19:00:
In Reply to: CO2 bulk fill question posted by Jeff Guinan on August 20, 1999 at 23:42:07:
Please pay attention to DT's advice, particularly about slightly underfilling tanks in hot weather.
I've recently had several burst discs blow on tanks that were filled to spec . . . which is very disconcerting while you're driving.
Plus, unless you have a paintball store nearby, there's no way to replace those discs on a Sunday afternoon (which is when they always seem to blow).
B.
-------------------------
BACK TO TOP
Pay attention to the timing of Quick-fill
Posted by Alan in GA on August 21, 1999 at 14:57:37:
In Reply to: CO2 bulk fill question posted by Jeff Guinan on August 20, 1999 at 23:42:07:
DT Fletcher said about all that can be said,
except I will add this: their is a TIMING factor in filling a less than
full tank of any size. Consider both tanks at same temperature with an
almost full SUPPLY tank and a partially filled 'slave' tank(the one you
want to fill). With quick use of the 'T' valves(2), you can 1)open 't'
valve closest to the slave tank for a second or 3. This will DROP the pressure
in the tank and the liquid in this tank will start to 'boil' which will
'recover' the pressure back to normal, lets say 1000psi. The 'boiling'
action will try to build pressure, but the valve being open will not let
it recover. You then shut the 't' valve which will close the system and
START the slave tank on its way back to 1000psi from let's say 700 psi
as the boiling liquid CO2 does it's thing. This will take about 3 to 6
seconds to reach 1000psi. IF you open the SUPPLY 'T' valve at the supply
TANK(remember it has been resting and up to 1000 psi) quickly, the supply
tank at 1000psi will FILL the slave tank because the slave tank is still
climbing from 700 psi. The supply tank will transfer liquid into the slave
tank only until the slave 'recovers' to 1000 psi itself. Remember, we only
need a few ounces to get to a 70%fill(NEVER EXCEED,YES NEVER!) This quick
action with the fill valves will allow you to get whatever liquid you need
in the second(slave)tank. Watch and ask your paintball guy how he does
it. It works. This quick valve action acts in unison with the naturally
occuring 'chilling' that also slows the recovery of the slave tank. My
typing fingers are tired. Alan in gA
------------------------
BACK TO TOP
.
What do YOU pay for a 5lb or
10lb Co2 re-charge?.
Posted by C. Brown on August 18, 1999 at 18:09:45:
I filled my 5 lb'er w/riser tube ( takes
a little longer to fill ) the other day at the local welders supply. The
price had risen to $16.85. Last time it was 14, time before, 10. I was
wondering what people around the country are paying. Clerk said there was
a new $ 5.00 Hazardous surcharge. (?) BTW, 10 lbs cost one dollar (1) more.
Remember that when you get that first tank folks...........A curious gas-passer\
------------------
posted by C. Brown on August 18, 1999 at 18:09:45:
Originally They were charging me almost
$10.00 but after they got to know me(and the manager turned out to be the
proud owner of an RWS 48)they dropped the price to DEALER .
BTW, I always had trouble with siphon tubes,
the guys installed them for me(modest fee)but It seemed like so much went
to waste, maybe a lb or 2lbs out of 15, and the tubes in mine went all
of the way to the bottom of the cylinders, so I had the tubes removed and
decant upside down.
---------------------------------
Posted by Mitch on August 18, 1999 at 23:08:23:
My supplier (DeLau Fire Protection, Lansing,
MI) charges $10 (taxes included) for any tank up to 20lbs. Some of the
welding suppliers are around $8 for five pounds, but they usually want
more than 10 for a 20lb fill. IIRC, it took about two minutes to fill my
20lb w/dip tube. I think I paid $12 for a hydro last winter. I've heard
that restaraunts pay about $6 for 20lbs. A friend of mine who buys for
a biotech firm pays $13 for 50lbs.
-----------------------------
Posted by Bill
B. on August 18, 1999 at 18:21:15:
Costs me $20 to charge a 20# tank here in the world's most expensive suburb (next to New Canaan, of course).
BTW, I have found fire extinguisher places much easier to deal with, less costly and far less likely to rip me off than welding gas suppliers.
For example, the largest welding supply house in the county wanted $75 and three weeks to hydro a tank. A firefighting supplier did an overnight hydro for only $10.
Got more horror stories, if you want 'em, Curt. But for my money, it's the fire guys first and foremost when it comes to CO2.
HTH,
B.
------------------------
BACK TO TOP
5 lbs vs. 20 lbs tanks
Posted by DT Fletcher on August 20, 1999 at 00:57:20:
I have been using a 5 pound tank for a few years but I end up going to the fire extinquisher shop too often. So, I just ordered a 20 pound tank fitted with a wheel valve and a syphon. The guys at the shop think the airgun shooting thing is pretty neat and they are giving me a discount and the 20 pound tank will only cost me $85 (filled) normally expect about $100-110. . It costs $10 to fill the 5 pounder and it will cost $20 to fill the 20 pound.
It does take some time to gain back the cost of the tanks, but that is a pretty minor point. A model 160 with the MAC-1 extension and bulk fill simply kicks butt. The bulk tanks also also pretty essential if you want to take advantage of the great 111,112,115,115 Crosman bulk fill pistols.
The trick with weighing CO2 guns is a scale that has the ability to weigh relatively heavy items but still have .1 gram resolution. You can get away with 1 gram resolution. I have found the Ohaus dial-a-gram with accesory weights to be pretty good. It can handle every gun I shoot except it is neccesary to remove the stocks of the rifles. Very few digital scales can handle the weight of a rifle and still provide .1 gram resolution, which is why I ended up with the Ohaus analog.
For a bulk fill CO2 shooter the scale is the gas
gauge of their guns. You want it to be fast and accurate. With the Ohaus
it is possible to put the gun on the scale and tell exactly how many full
power shots are left.
dt fletcher
-------------------
Posted by Mitch
on August 19, 1999 at 12:08:11:
You can buy tanks, rent them, or lease them, but I haven't heard of people leasing smaller CO2 tanks. If I recall correctly, renting a welding tank requires a deposit and about $5 a month. CO2 tank rental is probably similar. A new 5lb tank is around $70, a used 20lb is typically around $100-120, but there is one fire extinguisher shop near me that sells 20lb tanks with fresh hydro and 20lb of CO2 for $85. You can either turn the tank upside down or have a siphon tube installed so it dispenses liquid CO2. If there is debris in the tank, turning it upside down will get the debris in your gun. The heavier the tank is, the less convenient it is to invert it. Many welding gas shops don't do CO2 on site, so if you own a tank from them they will usually swap it so you don't have to wait for your tank to be shipped out and returned. If you do this, you can usually avoid paying for tank maintenance by swapping the tank just before it's due for a hydro test. (I get my welding gas from Michigan Airgas, which no longer swaps customer owned tanks for that reason) Since I get my fills from a fire equiptment shop, I just take my tank in, give it to Bob, the tank technician, and he walks it over to the scales and fills it. I go up to the front office and pay them, and the whole process takes about five minutes. That's why I get my CO2 at the extinguisher shop even though I have an account at a gas supplier.
The CO2 tanks have CGA-320 valves on them. You will need something that screws onto a CGA320 and hooks up to either your gun or a to a transfer bottle. Bulk fill Crosmans came with 10oz transfer bottles with 1/8" NPT fittings. Most of MAC-1's bulk setups use paintball tanks, so you would need a paintball fill station. MAC-1 sells a simple paintball fill station for under $15 I believe. I think they also have a fill setup for the Crosman bottle at a similar price. I use a paintball fill station, and I got a paintball to 1/8" converter I use to fill my Crosman tank. My Crosman Skanaker came with its own fill station, which is not compatible with my other bulk stuff. If you buy a Skanaker, make sure it comes with the fill hardware.
You should also have a way to tell if you have
overfilled a tank. MAC-1 sells a small postal scale you can weigh your
bottles with. I have an Ohaus lab balance that I got cheap at an auction,
but it still cost about 10 times as much as Tim's little scales.
---------------------
Posted by Bill
B. on August 19, 1999 at 14:42:08:
Mitch's experiences have pretty much mirrored
mine.
Only thing I might add is that more than saving
you money (albeit over a fairly long term), bulk filling offers better,
more consistent shooting performance than using 12-grammers. That, of course,
leads to buying lots and lots of 3.5 oz. hangy tanks at $25-$30 apiece
as you bulk more and more guns.
Ain't this a fun hobby?
B.
