GTA
Airguns by Make and Model => Benjamin Airguns => Topic started by: RodJ on September 24, 2020, 09:16:13 PM
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Hello all. Has anyone ever encountered a problem where chambering a pellet in a Benjamin 39xPA was difficult? I picked up a gently used rifle and having this problem. I chambered a pellet and pushed it back out gently, and found that the head is being crushed and shaved a bit at the 6 o’clock position. Probing down from the muzzle with a .177 coated cleaning rod doesn’t detect any abnormalities.
Thoughts? Almost wondering if there’s a defect in the lip of the air transfer port, and if so, whether it can be cured. Or maybe a tight chamber mouth? That didn’t make sense in that the deformation is always in the same 6 o’clock position.
EDIT TO ADD: Forgot important info the rifle wasn’t holding air so I resealed it - bronze valve. The valve was extremely difficult to remove and was being scratched by something around the 2 o’clock position. I had to use 320/600 wet dry to smooth it out. The burr was further back toward the rear as I recall.
Thanks for any help.
Rod
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Seems there is a burr on the transfer port....
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You’re right, I measured where the resistance started and it must be the port. Weird. I can’t feel it with a thin wire, and a pellet pushed from the muzzle has no problem going past the port.
I feel a hardened steel 4.5 mm pin in my future to swage any burr on the t port.
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Just ordered two drill bits, size 16 and 17, each regular HSS and six inches long. 16 is .177 inches and 17 is a few thousands smaller (.173”). $5 total delivered to my door. Should be able to access the loading port (after removing the bolt) and gennnnnnntly probe and remove a burr if its in there. Start with the 17 and move to the 16.
Just mentioning it in case someone else has an issue like this.
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Probably a transfer port burr. But make sure your bolt prob is straight. I had one with slightly bent prob causing similar problem.
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Probably a transfer port burr. But make sure your bolt prob is straight. I had one with slightly bent prob causing similar problem.
Michael, Thank you! I’ll definitely check. That would make a lot of sense, because I can’t feel a burr with a cleaning rod and a pellet will go the opposite direction (muzzle to breach) without any deformation. Also, I had not thought about this, but occasionally a pellet chambers without a lot of resistance and other times it’s very difficult.
Really appreciate your taking time to post that.
If the next thing you see is “For Sale: two drill bits, new still in package...” you’ll know it was a bent bolt probe. Lol!
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END OF STORY
A six inch #17 and #16 drill bits worked but it took some finesse to not screw it up. In the end, the burr was tough, tapping the .177 bit against the burr merely logged the drill bit. Needed pliers to get it back, so resorted to a cordless drill :o In order to not make things worse, I measured on th bit and made a mark to locate how far to go in and only a tad bit further to nock down the burr. At super slow speed, with some oil, and only a few seconds at a time the burr got eaten and showed up as brass bits on the drill bit flutes. Next I got some polish compound and very gently with the bit centered in the rear port, smoothed it ou. Pellets now,go in normally and seat with a bit of pressure and without any deformation.
Funny, resealing this rifle I had problems with the valve cartridge dragging on something and scratching. Had to hit it with 320 wet dry to take it out. Otherwise it was enough to cut the o rings. Either someone tried some ham handed mods or it was that way from the factory. It did not hold air when I bought it and explains why the guy sold it. For $50, a $20 seal kit, and a couple,drill bits at $5 I have a nice 397 PA and it seems to shoot hard and accurately. Plus some nice wood.
Typing this up in case someone has a similar problem.
Thanks
Rod
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Good save on that rifle! Good to hear it’s functioning properly and shooting accurate now. 8)
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Thanks, I’ve taken a recent turn toward repairing pumpers in the Covid time. It feels productive, it’s a learning curve, keeps off the street corner, and it brings back something to “life”. And they’re sooo much fun to shoot.
It’s in terrific shape. And if it does group well at longer range, I may put on a peep or scope it for grins and giggles. Unfortunately I’m in a suburban neighborhood so need to be careful and I mostly just shoot in the garage at very close range. Fortunately it’s also a suburban neighborhood in Texas. Neighbors are not freaked out by the sound and I try to be polite.
Stay safe and thanks again.
Rod
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Rod,
I agree on the fun factor with pumpers. Lol, I have 4 880’s, a winchester1977xs, a 397, and 2 392’s.
Every one of them has proven to be a tack driver with the right pellet or pellets.
Some of them are pellet picky and others I have will shoot just about anything I put in them!
A peep sight will definitely let that 397 shine, especially if you have good eye sight. It’s almost as accurate as a scope.
:D
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Hello Buddy, thanks I have a Williams on my 392PA and it works very well even though my eyes aren’t that great. I may transfer it to the 397 for sighting. Also wondering about scoping one. Be kind of fun to really wring out the most from my bad eyes.
Btw, good list of air rifles. Some might say you have a problem... ;)
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Nice to hear about a woody coming back to life
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That's what she said.
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That's what she said.
Aaaaand there’s always one rubber chicken in the crowd to keep everyone giggling. ;D 8)