Battery should not make a diffrence i agree . Yet i have found that it can . Wether its due to the quicker compression and release of spring i dont know.
Nah......
Think you would have to have the gun cycling at say 100rps
Vs
Stalling mid cycle and ultra slowly crawling to slip of last tooth on release
THEN you "might" have say 1mm max difference on spring compression/release
Taking one tooth when Short Stroking as say a max of 15fps per tooth (maybe 12-13fps)
a 1mm spring compression difference would equate to say 4 fps tops
BUT TBH this is going some to get this variation of spring compression
most likly just a bit of random luck/slack in drive chain or wear gives a fly's pubic hair variation
Plus you get variation of 5 to 10 fps anyway between shot after shot
minor imperfections in bb's exact weight, slight imperfect seal on bucking lips etc....
The biggest variation in fps is to do with a leak, say sealing on bucking lips
(softer buckings blow on higher fps)
But often if isn't bucking seal or torn/damaged bucking etc....
One of biggest areas is piston o-ring losing 30fps or more
Or a bad leak/loose cylinder head etc....
Speed will not alter the fps - loads of other factors will
lack of good compression and ultra great seals is where nearly all energy is lost
No point putting in a m110 - m120 spring to compensate for $hit seals
stuff just works harder and runs warmer/slower to make up for inefficiency elsewhere
If you got a drop fps it will very very likely be down to three things....
Piston O-ring crap seal
Torn/damaged bucking
Extremely worn/faded spring
(though you would have to stupidly leave it pre-cocked for a while in general)
Stuff usually wears & not improves over time like fine wines
Careful of grease you use for o-rings, many eat up rubber o-rings
So a couple months later your o-ring will no longer seal well
Other than that, a part failure or bad assembly will cause a drop in fps
Or really daft thing to ensure your chrono-ing with 0.20's and not 0.25's
(just make sure you are reading 300fps on 0.20's not 0.25's)
If your APS varies 20fps that is a seal issue
the o-ring could get warmer cycling faster from still
but should after a few shots start to seal better
the warmth will help the o-ring expand & seal better increasing fps
BUT in reality that increase is down to $hit seal to begin with
Do a load of compression tests and you get so-so compression often
but after a few tests/pumps it improves a little
Really what you want is great compression to begin with in the first place
It is something not always easy to attain straight away
You can get a good cylinder/piston/piston o-ring within a few attempts
Or you can spend ages messing around with combos especially in piston head & o-ring
Some piston heads are just complete crap and believe it or not
some cheapo stock piston heads are very good if you set it up with good o-ring
bought a number of piston heads and quite a few were pretty crap or worse than some stock
(G&G is the exception, very rarely have I got really great seals on G&G piston heads)
But some china guns, the piston heads are quite good if you just replace the o-ring
(often china guns will over volume a smidge with crap o-ring seals to compensate)
Getting good compression is vital, and using stuff like synthetic super lube is a must
Other grease will quickly rob you of fps when o-ring gets perished by wrong grease
