Power on 12" barrel?
What power Is the airforce 12″ barrel good to? I’m guessing after a certain power or speed the groups will start opening up?
TIA,
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Viewing 13 replies - 1 through 13 (of 13 total)
Does the valve have a spring?
Thanks, 60-80 sounds a good number 😉 Was that from a 200bar fill? I noticed on my rifle the curve was very bad shooting from 200bar. It would drop 5ftlbs very quickly!
I’ve shot with a higher preload on the spring than this Doug but I took out 1 small spacer earlier today. I never noticed any decrease In power so thought I was on to a winner untill the 6th shot, then I needed a new set of undercracks 😆 I would of thought 150 bar would be plenty to close the valve and I’ve shot down to 90 bar and not had the tank dump? Strange 😕
You got me on shot count, I forget. A bunch. Sixty to 80? I generally get bored and chrge the tank again long before I hit 2000.
For sure getting 30 changed the shot count so badly I decided to switch to the longer barrel instead.
I’m not sure what to say about your tank dumping, except to think that maybe you’ve got too much static load on the hammer? In the end the valve has to force the hammer back to close. All it has to do that with is the return spring in the valve (generally none too strong) and the back pressure of the tank (always dropping).
I’d start off by backing the hammer spring off and see if that changes anything.
Good luck.
Doug Owen
Thanks DKO. How many shots could you expect running 20 FPE, 12″ barrel and the 500cc air res? I would of thought 30FPE and the 12″ barrel would eat up the air.
All the air Is out Mam as It dumped It 😆 The valve seems to be moving freely though so don’t know what else to try. It’s asif the pellets are trying to go down the barrel sideways? I’ll get some pics of them up later. I never had It dump the tank before I took a spacer out so wondering If It could be that? Sounds unlikely but can’t think of anything else?
Let all of the air out and check the valve operation…Make sure that it it moving in and out smoothly….
While you can run them hotter, IMO 20 fpe is a good spot for .22s. Lots of shots, excellent accuracy.
30, while you can with heavy pellets, doesn’t seem to work as well for me as JSBs at 750. Were I to be shooting at longer ranges, I’d run it hotter, but I think 20 is a good level for the short barrel. I’ll go to 24 inches after that.
Good luck
Doug Owen
No power wheel on mine so i have to alter the the spring tension by adding or removing spacers. That’s the least of my troubles now, the tank keeps dumping 👿
Do a 2,900psi fill. Put PW on 10. Start shooting 5 shot groups off a bench until you see the groups tighten up….I would check the tank first and make sure it is putting out a consistant fps….If it is not, you will have a hard time finding the sweet spot….If it is putting out consistant fps A PW10 you could lower the PW setting until you see the fps consistancy start to go away….
Cheers fellas. So really any barrel would be good up untill SS speeds? Surely there must be a point before that were a longer barrel would increase accuracy? That’s the point I’m looking for on a 12″ .22 talon barrel 😉
When I had the 12″ Kodiaks at 755 fps and CP’s at 850fps. You can get a bit more then that with a valve job. But I never push pellets past 1000fps. I try to keep them around 950fps.
It keeps them consistently accurate for me at that velocity and shoots whatever I want just fine.
There was thread on the Yellow forum a while back that had a graph showing turbulence at varoius speeds, and there was a big spike at around 950 fps IIRC, which suggests that 900-925 is probably the sweet spot. The SS can definitely do that (or more) depending on the tank/valve/power settings/pellet being used.
Here’s the thread: http://www.network54.com/Forum/79537/thread/1236169565/For+anyone+doubting+speed+of+sound Unfortunately, it looks like the graph image isn’t working any more.
Generally, accuracy degrades once the pellet goes supersonic (about 1100FPS +/- ).
That rule applies for any barrel, not just the 12″.
At subsonic speed, if you’re having accuracy issues, it’s likely the pellet more than the barrel that is creating the problem.
Viewing 13 replies - 1 through 13 (of 13 total)
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Yes the valve has the little spring In.