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mitchell A

350 fps 407 mm barrel

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sup chaps,just wondering what spring you guys would recommend to get just under 350 fps with a 407mm barrel, and if there was some srt of way to essetially calibrate the fps

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+1 on getting a chrono!


There's a bit of science but too many variables to give you an exact answer.


Just changed my M4 super short barrel to a 300mm ttb and found the M100 way too hot(390 fps), M90 a nice 345 fps.

The same springs in the short barrel were 360/305 respectively so it is a lot of experimentation.


I play both woodland and CQB scenario so in my case its just easier to adjust FPS by changing barrels


Weirdly the original set up on my gun had a very high cylinder to barrel ratio so fitting a longer barrel actually made the gun more efficient but I did lose the nice crack sound on pulling the trigger. If your cylinder is set up for a shorter barrel fitting a longer barrel may screw stuff up!


BTW my short experience in tinkering has learned me this,


dont bother change stuff unless its broke or shooting bent

dont bother cutting springs, just get a lower rated spring

FPS is nothing without control ie decent air seal, hop rubber and setup

hide the receipts from the mrs

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Get a chrono, nothing beats having one

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