random shot falling short - under powered as well.

[emergencychimp]

I have a g&g m4, CQW rush. I have added a silencer to it and shortened the outer barrel, overall though this increased the length of the outer barrel and my shortening of the outer barrel caused a little wobble in the outer barrel, meaning the inner barrel was too short and occasionally when my bbs would clip the inner end of the silencer causing erratic and very short shots. I have since added a tm sopmod 6.08 inner barrel, trimmed to the right length and crowned.

The trouble I have is that very occasionally (maybe 4-5 in every 100 rounds), the bbs are noticeably under powered. It averages 325 fps, has a new tm hob rubber and bucking and powered by a 7.4 lipo. These tend to come in groups and a short full auto burst seems to clear any problems.

Whats causing the under powered shots?

[dadio]

Re: random shot falling short - under powered as well.

could be a hop alignment issue, had something similar on some scratch builds, first shot drops short but on auto full power. hop and nozzle not perfectly aligned meaning the nozzle fouls a bit on the hop and makes a poor seal.

[emergencychimp]

Re: random shot falling short - under powered as well.

could be a hop alignment issue, had something similar on some scratch builds, first shot drops short but on auto full power. hop and nozzle not perfectly aligned meaning the nozzle fouls a bit on the hop and makes a poor seal.

How would I fix this?

[Figjam]

Re: random shot falling short - under powered as well.

I had it myself a while back. Took hop rubber off and tried again with it. Fixed it straight away, no more problem. Sometimes it just doesn't go on right first time.

[emergencychimp]

Re: random shot falling short - under powered as well.

cheers all, planning to get a new hop nub as well, so will do it all at the same time.

Thanks!