prowin m4 hop up in vfc hk416

[Mindspeed]

My googlefoo is failing me. I put a prowin hop up in my vfc hk416 and now have very poor compression.
Does anyone here have experience with this setup? Is there anything I have to mod to make it work?
The stock hop up works fine with the same barrell and bucking.

Thanks for reading.

[Vulpes]

Hope this isn't necro-posting here

I don't have any experience with the prowin, however you may want to disassemble and re-assemble all over again, maybe you missed something or a part is out of wack?

I have had barrels not match up with hops before, what barrel are you using? Check and see if your barrel is loose or wobbling, that would drastically lower your performance.

-Vulpes

[AndyC]

I had one of these in my LR300 and had the same issue. It appeared that(on mine at least) the opening for the air nozzle was too large in diameter and the nozzle wasn't sealing. I switched to a VFC 417 hop which is the same as the 416C and will fit most M4-type setups with slight modification to the side fins. Haven't had an issue since installing that.