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 ?

View attachment 140340

 

[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.

 

[Pollynator_bravo2]

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

Spring I think in m100. Cylinder I can’t remember the exact type but the port looks to be about two thirds down the cylinder

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.

Ok cool I have a couple of stock buckings I can try. Maple leaf have given me the occasional issue in the past however this one looked to be positioned correctly compared to those that have given me grief

 

[ak2m4]

cylinder vents sounds right, as other said chop and change the chamber and/or the nozzle

 

[Colin Allen]

I would start by swapping out the hop unit or pairing it with a Maxx nozzle; the Maxx hop units are very picky and can be prone to power fluctuations if they are not happy.

 

[Pollynator_bravo2]

I would start by swapping out the hop unit or pairing it with a Maxx nozzle; the Maxx hop units are very picky and can be prone to power fluctuations if they are not happy.

Yeah it’s paired up with a Maxx nozzle as I had also read this so was a bit miffed when I ended up With problems tbh

 

[Colin Allen]

Yeah it’s paired up with a Maxx nozzle as I had also read this so was a bit miffed when I ended up With problems tbh

I would still try changing both the hop unit and the nozzle.

 

[Pollynator_bravo2]

So tried changing bucking and it got worse, tried different barrel still bad. Checked compression on nozzle (should have done this before) and Maxx pro noz was leaking loads. Tried another max pro noz and same thing. Switched back to shs and hey presto it worked a treat. Now consistent fps at 270/280 and 0.9j-1j on 0.28g. Happy days and thanks for the help folks 

 

[Colin Allen]

So tried changing bucking and it got worse, tried different barrel still bad. Checked compression on nozzle (should have done this before) and Maxx pro noz was leaking loads. Tried another max pro noz and same thing. Switched back to shs and hey presto it worked a treat. Now consistent fps at 270/280 and 0.9j-1j on 0.28g. Happy days and thanks for the help folks 

Excellent!  That is a success.