FPS weirdness

[SilentSparky]

My son recently brought a Cybergun SCAR, it was a bit low on power 250ish on a .25.  So I opened it up checked the airseals, regreased and put in a M105 spring (it's what I had spare).

Put it all back together and chrono'd it a day or so later ~300 on .25 perfect, thought it may of been cutting it fine with the M105, but whatever... two weeks later we take it to a game and it chrono's at 335 and once we get home I get a similar reading.

No change to hop, same BB's, the only thing I done in-between was change the Tamiya connector to Deans, so any idea's to why this has happened? I can only put it down to things have just settled in, as the FPS kinda makes sense on a M105 spring, odd though?

 

[Cr0-Magnon]

Was 335 on a 0.25 or 0.20?

 

[EDcase]

Yeah, most likely bits settling.  I've heard that after a few hundred rounds the hop rubber gets properly worn-in and smooths out consistency.

 

[SilentSparky]

All on 0.25's

 

[Rogerborg]

Well, magnets.

Cold springs can be a bit hotter, but not by that much.  I'd guess at air seal, and using my forensic imagination, some piston grease has made its way forwards and sealed the nozzle up.

Take the win and swap the spring.  I'm down to an M90 on my CYMA M4 due to randomly fortuitous air seal on completely stock CYMA gearbox parts meshing perfectly with a ZCI hop, Maple Leaf lips and a ZCI barrel.