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.

 

 

[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]

5 hours ago, concretesnail said:

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

yes regardless of the mag used issue occurs

 

2 hours ago, Asomodai said:

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]

12 hours ago, Asomodai said:

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.