Fps drama

[Pollynator_bravo2]

Evening all,

so I have put together a quick build with some bits I had in the garage. I brought a max pro hop as the spare I had was bust. It’s running a max 21.25mm nozzle, maple leaf bucking. Compression from cylinder was fantastic no leaks. Inside the gb is a 13:1 gear set with a ASG 18k motor. I had two inner barrels that I’ve tried a brass 280mm and a steel 240mm I think. I am getting on the brass a range between 160 -280 and on the steel it never got past 150. 🤦‍♂️ 

there is no delay chip on as there wasn’t in this gb before. 
any ideas ?

[Pollynator_bravo2]

FYI was testing with 0.28g bbs. I grabbed a hi cap mag to test but normally I run mid cap pts epm1 mags so not sure if it’s a feed issue?

[ak2m4]

What's the cylinder type, and what's the spring if you happen to know?

[The_Lord_Poncho]

With that much fps variation, potentially the bucking is folding at the lips? If you haven't already, maybe try a variety of different buckings, and ideally a different hop chamber at least to rule that out.