Others My Gunnar is broken??

[coolsound]

I think my Benjamin Gunnar .25 is broken . after only a few hundred rounds, it's accuracy has become very erratic. It is 4-5 inches all over point of aim at 40 yards. It was pretty accurate at 50-60 yards and I designated it as my pesting sniper. I thought the barrel needed cleaning but it is the same after the clean. Tested it with 2 different scopes just to make sure. Gun seems to function fine and my little chrono measured the speed at 890 FPS. Only thing I can think of at this time is the barrel is so soft that it deteriorated after only a few hundred shots.

Just sent an email to Rich at Airgun Revision to see if he can help. I hope there is an aftermarket barrel option available. Can't find any instructions out there on how to disassemble the gun.

Let me know if you have any suggestions for troubleshooting.

 

[Dogowski]

I think my Benjamin Gunnar .25 is broken . after only a few hundred rounds, it's accuracy has become very erratic. It is 4-5 inches all over point of aim at 40 yards. It was pretty accurate at 50-60 yards and I designated it as my pesting sniper. I thought the barrel needed cleaning but it is the same after the clean. Tested it with 2 different scopes just to make sure. Gun seems to function fine and my little chrono measured the speed at 890 FPS. Only thing I can think of at this time is the barrel is so soft that it deteriorated after only a few hundred shots.

Just sent an email to Rich at Airgun Revision to see if he can help. I hope there is an aftermarket barrel option available. Can't find any instructions out there on how to disassemble the gun.

Let me know if you have any suggestions for troubleshooting.

Man that sucks! It's not even broken in yet. Might check the barrel grub screws to make sure they got snugged down properly at the factory. Hopefully it will be a simple inexpensive fix man. Keep us informed and good luck on the repair!

 

[PasadenaMike]

Tighten everything and clean the barrel

 

[coolsound]

Barrel cleaned. Everything looks tight including the barrel. Been using the same JSB 25.39 gr ammo. Sucks ...

 

[PasadenaMike]

Barrel cleaned. Everything looks tight including the barrel. Been using the same JSB 25.39 gr ammo. Sucks ...

Try a different scope. Did you chronograph it?

 

[coolsound]

Already tested using 2 different scopes to make sure. Yes Chrono at 890 FPS.

 

[PasadenaMike]

crown and breech ok? Try single loading

 

[coolsound]

Yeah they seem to be OK. Not sure the the 2 magazines can cause accuracy issue.

 

[PasadenaMike]

Yeah they seem to be OK. Not sure the the 2 magazines can cause accuracy issue.

(This is a joke) -FOR SALE: Benjamin Gunnar parts gun need money for another Leshiy 2

 

[Florida_Man]

I’d check for a burr on the transfer port. and possible buildup of material on that. Is it a breach oring or probe o ring?

 

[Hateful McNasty]

Yeah they seem to be OK. Not sure the the 2 magazines can cause accuracy issue.

You'd test single shot /ss tray to see .
There's examples around that a mag not feeding right or whatever can damage the pellet and cause poi issues / off behavior.

 

[Pnwairgunner]

Sounds more like damaged pellets to me….possibly a bad breech o-ring or one of the outer barrel o rings is bad.
I’d also try removing the baffles and try it again and see if there’s some baffle clipping going on.
You have not worn out a barrel by shooting a few hundred lead pellets hahahaha when the issue is found it’s going to be a very simple one, and you’ll be right back to being accurate again.

 

[coolsound]

You'd test single shot /ss tray to see .
There's examples around that a mag not feeding right or whatever can damage the pellet and cause poi issues / off behavior.

I guess I can try feeding it manually and see. No ss tray. It would be a coincident if both mags got damaged at the same time.

 

[coolsound]

Sounds more like damaged pellets to me….possibly a bad breech o-ring or one of the outer barrel o rings is bad.
I’d also try removing the baffles and try it again and see if there’s some baffle clipping going on.
You have not worn out a barrel by shooting a few hundred lead pellets hahahaha when the issue is found it’s going to be a very simple one, and you’ll be right back to being accurate again.

Not sure what can cause the pellets to get damaged in the feeding/firing process. The same pellets are being used in the L2 without any issues so it's not defective ammo. Will try removing the internal baffles and see. Wouldn't a bad breech o-ring just cause the gun to loose firing pressure instead of deforming the pellets? That's what happen on my Marauder before. Everything on the Gunnar seems normal except the erratic POI.

 

[coolsound]

I’d check for a burr on the transfer port. and possible buildup of material on that. Is it a breach oring or probe o ring?

It's a breech o-ring. Just checked the probe closely and looks like there is some build up there. Cleaned it all up and will try tomorrow to see if it helps.

 

[coolsound]

Breech o-ring and outer barrel o-ring look OK. No sign of damages..

 

[PasadenaMike]

The gunk must be in the transfer port and barrel. Maybe a good scrubbing

 

[coolsound]

All cleaned again now including all baffles. Will test tomorrow morning.

 

[PasadenaMike]

All cleaned again now including all baffles. Will test tomorrow morning.

How was it ?

 

[coolsound]

Wasn't that dirty. Pull the patches (soaked with GIBBS and clean) through the barrel a few times until it clears of black gunk and scrubbed the breech/transport area with Q-tips.