GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: Ribbonstone on July 13, 2018, 10:37:21 PM
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A quick up-date on two posts: co2 12gr. wood stocked Hammerli 850 and a 12gr. lite striker QB 79 HPA conversion.
There go my plans for the summer. Either of these two will get the job done just about as well as the other (Job being pest birds in the back yard/garden during the off-season).
Not a whole bunch to choose from at the 20-25 yard ranges that cover the normal back yard (I could back up down the patio and make it 32-33 yardsif I thought retreat was the better part of valor).
The two rifles (OK.."carbines"):
(http://i157.photobucket.com/albums/t50/ribbonstone/co2/85c09064-6813-4a30-b375-7aca9ddb094d.jpg) (http://s157.photobucket.com/user/ribbonstone/media/co2/85c09064-6813-4a30-b375-7aca9ddb094d.jpg.html)
HAd thought the 12gr.running 850 would have beeen the "it" gun for ther summer. Kind of 10meter match speeds (6-6.2 foot pounds) and enough accuracy to count on. Tweety-birds are tweety-birds, they don't take a lot of "oomph" to blow thought them.
THEN...got all involved in a 11-12gr. striker project on a QB 79 HPA tanker. More like 9 foot pounds X 435-450 shots per fill.
Which as far as the MINIMAL difference in tracjetory is concerned over the 2-=25 yards, it's mnot "JACK". 13.4gr. at 543fps vs 7.9gr. at 562fps just doesn't cvome out to any useful difference in trajectory at short range.
(Yep...if long range was on thew menu, would have piocke3d a different rifle than either of these two.)
Somehow did they do as back yard plinkers?
Top rifle:
With the RWS/Hammerli/Umarexm 850, I did buy a 2nd dual 12gr.,tube, then prompley disarmed it into a single 12gr. adaptor. Just removed the 12gr. popping piece from the front end and let it run on one 12gr. (and a full 12fr, at the front).
A good solid 48 shots from that single 12gr. That will translate into +105 shots for dual 12g. (can get into the "why" of that non-proportiaonal increase in shot count if your really need to).
(http://i157.photobucket.com/albums/t50/ribbonstone/co2/5bb1ebe0-6b08-43bc-9563-12bd1c47de38.jpg) (http://s157.photobucket.com/user/ribbonstone/media/co2/5bb1ebe0-6b08-43bc-9563-12bd1c47de38.jpg.html)
VERY BIG PLUS for shooting the cherapest .177 pellets avialible local.... it the store has ANY pellets ,they will have Crosman 7.9gr."generic" tins (And a nod to Crosman for one *(&^ of a marketing job...they really went all out to cover the market.)
Bottom Rifle:
(http://i157.photobucket.com/albums/t50/ribbonstone/co2/5b003df5-8b87-4cf2-85f4-53dd03275fd6.jpg) (http://s157.photobucket.com/user/ribbonstone/media/co2/5b003df5-8b87-4cf2-85f4-53dd03275fd6.jpg.html)
TYted for a single 10 shot group each day. Each day it took a trip with me to and from work, laying in a gun sock on the floor boards of my Jeep.
It looked like ti got aweay from me on day 2...but basically, it stayed stable enough to be totally usefulduring a fill.
I do know which one I want come winter (QB 79HPA) but duri9ng the summer, am more likely to pick the 850/12gr. co2 for the ease of operation.
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Nice! I think the 850 can be modified to run 88/90 grams Co2 canisters with minimal effort,if Umarex left in place the piercing pin in the valve like in old 850's.You can also easily switch to a 12 ft/lbs valve.
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Excellent write up once again!
Seeing that you put a little more work into the light QB hammer made me smile. After seeing how they performed in my QB's I knew you would be find it to be a useful tool as well. I look forward to seeing where you use it next, whenever that may be.
I plan on testing the light hammers a little further and will share results. Next in line is to see what method I can add a little weight so I can convert my 50fpe bottle gun to a peek hammer. I like the muted hammer strike due to the composite face hitting the valve, so whatever I do will not involve a metal striker piece.....
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Started this just to see what would happen without any other mods...and for low power uses, it surprised me how well it did work.
Pretty much the appeal was to see just how many low power shots and how quiet it would get when using minimal air per shot.
Found that the low speed/energy I settled on was more a matter of an un-worked on valve and the amount of cocking force I found distracting (I really like to run them pretty effortlessly).
Seems to be an abundance of air rifles, and not all of them have to be powerhouses to be useful....are some tasks where power is counter-productive.
So for now, the .22 QB79 is staying with the lite-striker and the 8.6 foot pound setting. Still giving air use in the 360-380 shots per fill area.
And I've a length of the same Delrin rod ready to start the process in the old .177 AR2078. Likely, as I kept it pretty much the same shape as the orginal striker; should come out at about the same 12grams.
(http://i157.photobucket.com/albums/t50/ribbonstone/AR2078/69ab1a65-7c17-4d7c-8d02-9dc16395db85.jpg) (http://s157.photobucket.com/user/ribbonstone/media/AR2078/69ab1a65-7c17-4d7c-8d02-9dc16395db85.jpg.html)
The two HPA's started off at the same energy level with metal hammers (12.4-12.5 foot pounds), both at basically 200 shots per fill (3K to .8K). The .22 dropped to 6.1 foot pounds with JUST the striker swap (later it was adjusted a bit up to 8.6 foot pounds).
SO we'll see how much the smaller bore 2078 drops in power. The full length barrel might play a bigger part in this than I expect, might actually be strangled down to where firction is really taking it's toll.