Getting an AEG to feed properly at >30 RPS

[XZIVR]

Okay so I'm working on this gun.. Basically it's an excersize to see how far I can take it. It's a CQB gun and my initial goal was insane trigger response, and I got that.. Now I want to see what else I can do.

Things relevant to the setup:

edit: forgot to mention this is an m4 :P


Modify M100 spring (CQB FPS limits)
Standard torque gears (sector is short stroked 3 teeth on the leading side)
SHS full metal tooth piston swiss cheesed & ground for correct AOE
modified G&P M120 motor
AWS Raptor MOSFET
3 cell lipo 2200mah 30c
King Arms tappet delayer on the sector gear
King Arms 120rd midcap mags


So the chrono is sometimes catching as high as 35 rps, no idea if it's higher or not.. Haven't done an audio analysis. I was hoping for an even 30 RPS but hey.

Anyway if I fill a midcap and give it a quick burst, it will catch about 35 RPS. Then it goes down lower and lower each time, presumably because the spring in the mag loses a bit of tension each time and isn't able to force the BBs into the hopup fast enough. At its worst it gets down to 6 RPS, meaning at best it's able to chamber a bb 1 in 6 cycles.. this always happens when the mag is under half full.

It feeds each shot just fine on semi (as you would expect since the Raptor stops between shots with the tappet in the back position) and if I turn the adaptive ROF down to 20 on the MOSFET it will settle at 21. Since I already have the tappet delayer, I'm not sure if there's anything else I can do to play with tappet timing? Unless I could make/mod a bigger delayer?

Maybe there's something I can do to the springs in the mags.. I play with midcaps though, not highcaps, so perhaps my options are a bit limited.

Anyways any help or ideas would be appreciated. I know I can't be the first to have such an issue....

[Deathfox]

Well if you have a delay chip already then its your mid-caps. Its all about good mid-caps with high speed setups. TM ones are always a safe bet. What gun are you running?
Also if you can, using capacitors will help with voltage drops, and in the end help with RPS consistency.

I have a p90 that shoots 40-45 rps and it doesnt have a delay chip, and feeds great with GOOD mid-caps. Just need to make sure you put a drop of silicon oil after every game day, and never leave them loaded too long, and they will treat ya good

[XZIVR]

Well, the other thing the P90 has going for it is gravity is on your side. :P

I went with king arms mags because they had decent reviews, and the reciever is also king arms so I figured they'd have the least wobble. Tried SRC mags and they had a bunch of play in the magwell.

Well, I guess I'll play around with the mags a bit more and see what I can make happen, and if nothing good comes from that I will see if I can get my hands on some TM mags to try. Thanks for the suggestion.

[ThunderCactus]

Take the mags apart, put BB's behind the spring, then reassemble. Same effect as pinning the mags, but doesn't permanently change anything.
You probably just need more tension on the spring

[XZIVR]

Okay, tried that and it helped, but it still had feeding issues after the first 1/3 of the mag was gone. Be nice if I could get it to feed right to the last one, but maybe that's asking too much. 35 is pretty high..


Have to saythough, the KA mags are really nice inside. Single stack and there's this peg that fits in the bottom of the spring that stops the BBS before you try to load too many and cause the spring to clash.

[phloudernow]

high RPS should not effect you feeding, if you using highcaps there might be an issue with it not feeding fast enough, but midcaps should have no problems. You should try Classic Army Midcaps as i have a 35 RPS highspeed set up as well, cept mine is done the old fashion way with shortstroked gears and a 11.1v Lipo XD, you might also want to check your hopup, my gun feeds extremely well with the Magpul PMag Midcaps also. I run a Marui Hopup from a TM m4 RIS so its all good

[XZIVR]

Well, incidentally I tried a highcap I had laying around and it behaved the same way. I can appreciate the physics at work behind it all, and so far nothing has really surprised me as far as what I have observed while testing various things.


In any case I don't think I'm willing to spend too much money on it right now, because as a CQB gun I only use it in semi auto anyway. The one thing I did decide to try is I ordered a different tappet plate after reading that some can have too much flex and cause feeding issues in very high ROF setups. Cheap thing to try, don't think I will be buying more mags for it any time soon though. 2 midcaps gets me thgough a match just fine.