Problems with my Vulcan

[Rossco]

Hi all

ive bought a pre owner .25 Vulcan
one big problem. When chrono'd the FPS is all over the place, 750-850 all over..
what could be wrong here?

 

[DanWho]

2 things come to mind, the spring for the hammer is wobbly and striking inconsistently or the barrel is fowled and needs a good cleaning. Another possibility is the tin of pellets has lots of oddballs in it. Maybe someone lots more experience has a better suggestion, but until then that's a few areas to check out.

Dan

 

[guykuo]

That huge a FPS variation is unlikely to be barrel fouling or an incredibly inconsistent pellets.

Hammer spring binding is the number one suspect here. I would examine the hammer spring and how it is moving. Be sure the hammer spring isn't bent. Also, depending on whether it is an older one with a spring guide, the brass guide may be worn or binding on the hammer. 

Pull the action out of the stock, open the right side panel and examine the hammer, spring and guide. I would pull and clean them and the guide barrel. Relubricate with dry slide and recheck for FPS consistency. If after cleaning and verifying the hammer spring isn't distorted, the FPS variation remains bad, the next suspect is the pressure regulator.

That's a bigger project to sort and might be better taken care of by someone like Ernest Rowe. A mechanically adept and experience air gunner can service the air regulator, but it isn't terribly easy. You can get an idea of how that would go by reading the "vulcan .25 unstable velocity !! " thread over that the Talon.

Hopefully, its' just the hammer spring binding.

 

[Wager]

Check the breech o-ring also.

 

[Rossco]

Thanks guys
will strip down later tonight 
is there a strip and rebuild guide?

 

[jorgemac]

"Rossco"Thanks guys
will strip down later tonight 
is there a strip and rebuild guide?

Here are a lot of videos to see