Found another Benjamin 312
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Found another Benjamin 312
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Topic: Found another Benjamin 312 (Read 863 times))
TerryM
Expert
Posts: 1559
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Re: Found another Benjamin 312
«
Reply #20 on:
March 14, 2023, 11:34:23 PM »
A little update. I made another "hybrid" piston with a new 392 type cup built up with silicone, as done in this thread from 2021.
https://www.gatewaytoairguns.org/GTA/index.php?action=profile;u=11898;area=showposts;start=160
Made it as long as possible and still be able to clear the air intake hole. This helped some. I just finished replacing the pump lever and link with a rebuilt, tighter one. Amazing the difference it made. The gun now gets around 515 fps with 5 pumps, 540 or so with 8. I think I'm done with it. The old link had a copper rivet which was naturally worn, sloppy. I never would have guessed it would have so much effect on the pump efficiency.
I did the same thing with my Crosman 101 a few days ago, installed a new lever and link and improved the performance.
Logged
TX
Crosman model#
101, 108, 110, 112, 113, 114 (x2), 118,
140, 180 (x3), 187, 400, Mark II, 1377, 1322, 150, 122CG, Sears 126.19311, Ted Williams Match Rifle (2nd variant 160) Self made 180-400-114 hybrid carbine
Benjamin model#
312(x2), 317, 342, Discovery
Sheridan:
Blue Streak (x2: '64, '67)
F model CO2 Blue Streak (converted to bulk fill)
TerryM
Expert
Posts: 1559
yes
Re: Found another Benjamin 312
«
Reply #21 on:
March 15, 2023, 07:59:48 PM »
Okay, so I wasn't done with it. I noticed the gun would lose some pressure when I gave it 5 pumps and let it sit for a few minutes. I took out the rear plug and was able to tighten the valve nut a bit. Not only did it fix the leak, I now get over 540 fps with 5 pumps, tried a shot with 8 pumps, got 615 fps. I was quite surprised, it now shoots harder than any of my other old Benjis. Who'da thunk it?
Logged
TX
Crosman model#
101, 108, 110, 112, 113, 114 (x2), 118,
140, 180 (x3), 187, 400, Mark II, 1377, 1322, 150, 122CG, Sears 126.19311, Ted Williams Match Rifle (2nd variant 160) Self made 180-400-114 hybrid carbine
Benjamin model#
312(x2), 317, 342, Discovery
Sheridan:
Blue Streak (x2: '64, '67)
F model CO2 Blue Streak (converted to bulk fill)
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GTA
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All Springer/NP/PCP Air Gun Discussion General
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Found another Benjamin 312