GTA
Airguns by Make and Model => Crosman Airguns => Topic started by: DanD on November 11, 2019, 05:16:31 PM
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I'm sort of addicted to these little C9As and ended up with another. This one is a 1997 model with some very unique wood. The factory clear coat had some unsightly surface scratches so I stripped it off with Minwax Antique Furniture Refinisher and spent a week rubbing one or two coats of BLO per day back into it.
I've been wanting to get 600 fps in 4 pumps with JSB 13.7 as documented here: https://www.gatewaytoairguns.org/GTA/index.php?topic=162790.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=162790.0) , so I gave it a second go on this gun.
This one needed the valve haves opened quite a bit to remove headspace, and it took several wraps off Teflon tape and some muscle to close the valves against all the tape without leaking. I also caked some gasket sealant in front of the front oring in hopes of reducing headspace.
I again filled the valve with epoxy putty, but I tried to finesse the shape a little more this time. I used a late model "overmolded" poppet and turned down the shaft and the head in hopes of improving flow. I used a small hammer to whack the poppet onto the seat to get it to seal reliably. I stacked two full sized check valves and inserted a hammer spring guide into the shortened valve spring in order to use up more volume.
The results are about where they were before, except this gun has a little more power on the top end.
JSB 13.7 are doing 580 fps on 4 pumps, 630 on 5 pumps, and 730 on 8.
Benji 14.3s are doing 610 on 5 and 715 on 8.
JSB 15.89 are doing 590 on 5, 695 on 8, and 735 on 10.
I'm happy with 19 ft-lbs on 10 pumps even though it wasn't my goal.
So.... I wonder if the linkage geometry just cannot stuff enough air into the valve to hit 600 on 4 pumps.
Thanks for reading!
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Wow, is that some nice wood!
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Wow, is that some nice wood!
The best part is that it shoots as good a it looks! It's an accurate little devil.
5 shots at 10m, 3 pumps, iron sights, Benji 14.3 @ 492 fps.
I just love these late 90s Benjis!
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Good looking gun. Nice shooting with the open sights.
The pump linkage and brass tube do a good job at higher power levels.
However 600 at 4 pumps would take a very refined build. I have seen a 392 do it but .20 caliber is going to be a little slower.
I like the PA platform as well. I have seen 1100 fps with the 14.3 in .22 caliber.
That would be hard to top with a 1322.
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Dan...That is Very Nice Rifle !
It's a good shooter too !
Best Wishes - Tom
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Nice looking and accurate rifle!
Love the Benji and Sheridan’s! :D
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Beautiful rifle and great results in performance!
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Nice! Don't recall reading, hearing anyone reducing valve volume like you did in a 'dan. Between that and getting rid of that head space definitely got some decent performance.
4 pumps enough to hunt squirrel/rabbit at 30 yards.
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Nice! Don't recall reading, hearing anyone reducing valve volume like you did in a 'dan. Between that and getting rid of that head space definitely got some decent performance.
4 pumps enough to hunt squirrel/rabbit at 30 yards.
Thanks, Charley. The low pump hunting power was my goal. There's an arbitrary NYS regulation of a minimum 600fps to hunt small game regardless of projectile caliber or weight. My two low volume C9s will easily break 600 on 4 pumps with H&N 11.4 gr. I was hoping to get there with JSB or Baracuda 13.6-13.7gr but it takes an extra pump. Unfortunately I don't really hunt anymore, but if I do again, I'll be thrilled to hit the woods with one of these C9s!
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Nice gun and nice shooting with the open sights.Thats nearly one hole.I'm always eyeing those dans on american airgun classfieds..One day.