AEG Low fps on first mag

[Musica]

Got a Specna Arms Specna Arms SA-E12 EDGE which is stock apart from a prometheus purple bucking. Running a 7.4v lipo.

The first shots out of it are really low fps but then it stablises to be pretty consistent between 280-290 which is still a little low really.

Any one have any ideas' what could be causing this behaviour? The barrel is cleaned after every game day.

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[Rogerborg]

When I get wandering FPS, it's been down to the barrel not being seated tightly in the hop, or the hop not being tight against the gearbox.

 

[concretesnail]

the title mentioned first mag, does it happen regardless of which mags are used?

 

[Asomodai]

If you're using midcaps, it's probably midcap syndrome, the pressure of a fully loaded mag pushes the nozzle up results in lower FPS for the first few shots per mag. 

Either break in the springs on the mag or fill them a little less. 

 

[Musica]

the title mentioned first mag, does it happen regardless of which mags are used?

yes regardless of the mag used issue occurs

If you're using midcaps, it's probably midcap syndrome, the pressure of a fully loaded mag pushes the nozzle up results in lower FPS for the first few shots per mag. 

Either break in the springs on the mag or fill them a little less. 

will test this out.

 

[Adolf Hamster]

If you're using midcaps, it's probably midcap syndrome, the pressure of a fully loaded mag pushes the nozzle up results in lower FPS for the first few shots per mag. 

Either break in the springs on the mag or fill them a little less. 

once made a little tool for unloading a little from midcaps for this reason, used a bit of random steel but since found that an inner barrel is the perfect length.

cut a ~2" section, drill a hole in the cut end and stick a pin/grub screw in there as a stopper.

as for the general case of guns needing to "warm up" i've seen it happen but never really found a hard and fast reason why, my m4 pre-hpa conversion used to chrono stupid low (like barely able to lob a bb through the chrono low) in the mornings but once it had a few mags through it then rest of the day it'd be fine. best guess is that once the grease/seals warmed up from a few shots it'd start sealing properly although this doesn't explain why on a cold day it didn't happen again after lunchtime.