Weird feeding issues..
 

So I'm having a weird, intermittent feeding issue.

I have a VFC M4, and am using Mag 130rd vn style midcaps. The gun will generally feed the first magazine just fine, but sometimes upon mag change the next rounds will shoot very short and curve down (almost like extreme overhop) until I remove the mag, clear any bbs in the gun, and reload the mag. Usually after that it works fine. I do get the occasional shot that will fall very short midmag as well when the rest are going fine.


Anyone had an experience like this? Perhaps worn springs in the mag? Lack of lubrication? Its just such a strange issue I dont know what is causing it. Insight appreciated.

Sound's like a double feed,check your hop up chamber for movement forward and back play. Or it's the mag's try loading 10 or so less of a full load of BB's in the mag's.

Thought it might be this too but I could shoot the whole mag off and each round would be short. If it was pressure on the mag wouldnt it be relieved after a few shots fired?

when you fire one it'll load another so won't necessarily clear the problem

Oil/clean the mags? Might be some dirty or resistance in there. Had this in one of my MAG mags, most feed perfect, this one was dirty and I had similar, some mis feeds, used my air compressor and blew the channel, spring and plug removed, oiled it up, shot a couple mags, no problem.

I never got a single MAG brand magazine to feed in any guns I owned.
Their low/real caps are fine, because they are not double-stack.

All the mids have issues because the ramp from two to 1 BB wide is too steep, and the BBs jam.

Having the exact same issues with my VFC Scar and Socom Gear Troy Mags.

Please help.

Is it because I borrowed a mag at hornet? I swear everything I touch breaks D:

It mite even be the nozzle is sticking if you have occasional BB falling very short midmag.

Why have you brought this black magic upon me?

Exorcist pls halp.

It might've gotten a bit dirty while it was in my dump pouch tho

i have had similar problems its usually when i fill my midcaps up to the max? dunno why but if i put 30 - 60 rounds its fine then if i go over it fucking wont shoot or some shit =.=

What BB's were you using? I have found that problem too but it was because the BB's were smaller, by a fraction, which caused them to jam.

With 130 rnd midcaps what I find is they tend not to work to well with anything heavier than a .20 over time, when I was still using regular AEG I have to over time tear apart my KA Midcaps and re stretch the springs, at first i thought it was lubrication issue but it actually help fouled up the internal of the mags faster. In the end it was just a spring issue, if you are using a .25 or heavier weight bbs and have a habit of leaving bbs in your mags over a period of time the spring will sag like an old titties vs gravity. With your shots falling short and such it could be two things, one is a dirty barrel and hop up, two it could a worn hop up rubber or if it only happen in the cold then it's the actual hop up rubber getting too hard (freezing) it could happen even in as low of a temperature as 2C. It happen to me a few years ago when I was using my KA Galil, with a brand new concave hop it was like 1C and the shots was falling short and inconsistent, I find it weird because a few days before it was engaging like a freakin lasers at TTAC3, went home tore it apart to find the rubber is fine but a bit hard.

Well as far as the hop up is concerned its brand new.. lonex sleeve and modify flat nub. I did have the modify sleeve before as well and the problem was the same. The conditions are the same regardless of temperature as I'm testing it indoors.

As for leaving bbs in the mags, i'm pretty good about emptying them within 24h of a game.. but the mags are a few years old now. It doesn't seem to happen with my other guns though.. More testing is in order I guess.

McKee try the fittings on the mag release some may sit just a tad lower than OEM mags even by a small fraction but enough to cause the misfeeds, if its happening only in one rifle it might just be spacing issue on the mag itself or it could be your body getting too loose over time. some of the one I've seen on the newer AEG range from improper hop up alignment to the body to a small misallignment of the body itself, things like misallign body pin holes or even as common as a slightly bent hop up feed tube lips.

So far i've lubed/cleaned some mags, lubed the hop up, and have tried partial mag loads. So far partial mag loads have been somewhat successful. If I load to 120ish (basically till i cant load anymore, amount varies depending on how it stacks inside) it will shoot low if there is already bbs in the feed tube, but seems to improve after shooting about 20 shots. If i load to ~95 rds so far it seems ok but i havent tested it extensively. Even a fully loaded mag will still fire properly if the tube is clear, and sometimes even when it's not. Needing to fire 20 rds before it corrects doesnt make sense if there is only max 5 extra bbs in the tube. I am still not convinced even partial mag loads are reliable though and suspect there may be an underlying problem.. Especially since i havent replicated the problem on another gun.

I have this issue with 120rd PTS mags. I checked the guns feed and it was fine.. It ended up being the mags when (fully loaded) at 100-120rds or so. I would loose almost 15-25 bb's trying to get the damn thing unjammed and feeding... so I just dropped the count back 75-80 on the quick loader or so... and it fixed it.


To me, this is probably a break in issue where the spring needs to be compressed a bit so that it doesn't react so violently with that much force when un-compressing and feeding the gun.

I have the exact same issue with my VFC M4. After each mag change the first 6-8 shots curve downward and the FPS is really low. After firing off the 6-8 everything returns to normal. Using Magpul mags ( not the cheapie ones ).

I'll have to try loading up only 100 rounds and see if it makes a difference.

Bastards at the time.

I also got some silica ones, and they where feeding sometimes (I know they are smaller, but a lot harder and smooth).

Don't have the issue anymore, since GBBR...

Sounds like the same thing. Let me know how it works for you.

Update for McKee - Loaded up a bunch of mags today with 90 to 100 rounds each. Made no difference, the first 6 to 8 shots went about 50 feet and curved downwards.

Thanks Korunos.. here's something I've had some luck with. Fix a patch of female (soft) industrial strength velcro inside the mag well (you can get these at micheals craft store). This is a trick many VFC owners use since they are finicky with mags and the magwell seems slightly larger than most AEGs. Despite my MAG brand mags fitting ok without it, it seems to have helped with the feeding as well as tightening the seating of magazines (also makes your gun quieter due to slight mag rattle). This in conjunction with loading the mags under capacity seems to have rectified the problem, but I won't know for sure until I game it. I'm not about to blow hundreds of rounds off for no reason trying to test for a intermittent problem. I'll post back after my next game with results.

McKee, does this problem occur when using vfc brand mags?

I don't have any VFC brand mags. Just MAG and a G&P.

Crap, I just bought a vfc scar, guess what, same prob, I was hoping someone has vfc mags to confirm if it's mag related

MY VFC Scar H feeds flawlessly with the VFC mid caps :)

My VFC PDW feeds flawlessly with the VFC pdw mid cap it came with and the dboys pdw midcaps. I use velocity arms m4 mid caps with it too, although it shoots fine, the mag will drop out with very little pressure on the mag release. Had to use soft side of velcro to prevent it. M4 mags are not as fat so it seems that's the main culprit for my PDW and non-pdw mags.

Try velcro in the magwell?

I did this to my Scar and now it is shooting fine, so long as I don't over feed my mags by 10-20 or so rounds.

I know VFC mags are a little off from most standard AEG mags, hence why VFC mags probably work better the most other brands. If I am correct like Bennyboy pointed out, VFC mags are usually a bit bigger and therefore tighter in the magwell.

Try some black tape little in the mag well on the bottom of the mechbox and a little on the top of the mag.

I recently started having this issue aswell with my vfc scar light and king arms midcaps. I've had the velcro in the magwell since I bought the gun and my kingarms mags fed fine, but I forgot that I replaced the lower receiver and didn't replace the velcro, haven't fully tested yet but I assume that was my issue.
Also, my vfc midcap has had this issue out of the box, velcro tape or not, it still spits out the first 5-10 bbs, always has, seems like it always will.

By the way, I never put more than 80rds in my 120rd mags.

Thanks McKee, I'll give that a shot as well.

I was so stoked when i got it but the fact that I have SOOO many mags and non of them worked right was a big piss off. I think im going to throw that fish back in the ocean, or that gun back in the classifieds LOL

Alright so update here. Gamed my gun this Saturday and realized despite lubing the hop-up and shimming the magwell with velcro, the problem still exists.

My theory: It's for sure an issue with mags being filled to capacity. Arkell has a G&P XM177 but the same magazines (MAG VN midcaps) and has the same problem. I was loading them to approx 90 rounds (as indicated on my TM speed loader) and had to regularly shoot the first 8-15 rounds out before they would shoot straight. The gun shoots 400fps normally. The first rounds shoot around 180 until it fixes. Shooting upside down makes no difference.

I believe that the tension in the mag springs is such that when it is full loaded, the BB in the chamber is forced up against the top of the hopup with enough force that as the nozzle loads the BB it drags across the top and has enough friction to slow the BB substantially.

Any help with this issue would be appreciated.. somebody somewhere must have noticed this before.

This is a very common problem. As midcap capacities continue to go upwards, spring strengths have to increase somewhat too. The PTS PMAGs and TMAGs are well-known offenders. Interestingly enough, my Madbull TROY mags have 190 round capacities and do not seem to have this issue. I've run into overly strong mag springs in a variety of AK and M4 mags. I've seen several AEGs that have a nozzle/tappet subsystem that falls victim to this issue.

The thing is, you kinda *want* strong springs, since we all want good feeding at full auto, and we want good feeding with more friction/spin-producing BBs.

A solution to this problem which has been widely-observed to work is to strengthen your tappet return spring by removing a couple of coils. My usual solution is to cut two coils and then bend one more coil to create a new spring loop to hook the tappet to the gearbox shell. Make sure you take care to use a large wire cutter and to secure the coil while doing this to ensure you don't have your coil fly across the room.

+1. I've had to do this to pretty much ALL of my AEGs...

I'll just add that it's my belief that many many compression, feeding, BB-brand, bucking, barrel, hopup unit and mag issues are really just this problem, but mis-diagnosed as other issues.

Sorry....maybe it's just me. How does the spring pressure inside the mag cause air-leak/compression issue type symptoms?

I think he means the tappet spring is the cause not the mag spring.

Many ways.

The bbs could press up against the nozzle hard enough to cause air leaks between the nozzle and cylinder head. Basically, like a prying motion.

The bbs might press up hard enough that the nozzle doesn't seat completely forward and gets caught on the upward force of the bbs. Hence, why you increase the strength of the tappet spring to pull the nozzle back into proper position. I believe this is the symptom and cure Maciek is referencing and honestly makes the most sense in this situation. As the tension in the mag goes down, the nozzle moves more freely given its current tappet spring tension. As the nozzle moves more freely, rounds load better and the nozzle seats properly.

In two piece cylinder head setups the nozzle and cylinder head may not leak under the pressure, but the pressure on the nozzle may stress the two piece cylinder head where the nozzle meets the head (probably not very common) or where the cylinder head meets the cylinder (can also happen in 1 piece). This is probably fairly rare unless your cylinder head/cylinder is really poor quality

I notice that in tappet plates, there is play in where the nozzle sits. In the standard design, there are many areas for leakage in the interactions between just the nozzle, cylinder head and hop up. The fact of the matter is that the nozzle not only operates as a means to deliver compressed air to the bb but also to restrict bbs from entering the chamber. As a result, the entire load of the rest of the mag sits against the nozzle. If you release a fully loaded mid cap, you know how much force this has (hint: use eye pro). All that pressure on one small part that really isn't completely secure itself. That's where these issues arise from.

I believe Maciek has a good write up about this issue on his SIG and its very long nozzle.

(By the way, I know you probably know most of this, the length of this write up was for any other people who find this thread and want more info.)

Cheers!

Both are the cause actually. But really it's all our fault.

The key insight here is that if a given problem doesn't happen on a stock Tokyo Marui gun, it "doesn't count" as a design flaw. As soon as you start jacking up different variables across the compression or gear transmission subsystems in the Marui design, all sorts of strange and out-of-spec behaviour starts to appear. Big surprise, eh ? ;)

Now I'd love to go smack the engineer who thought it would be a great idea to strongly-couple the forward seal to the feeding mechanism, but he has a great excuse for his mistake: Stock Maruis don't have to produce Canada-ready velocities, nor do they have to contend with "high cap" midcaps from Taiwan.

No doubt about it though, as soon as this design had to contend with 120+ rounds pushing against the nozzle, having high trigger response from strong LiPos and also producing 360fps (or higher) in compression, it was going to show some cracks. There you have it.

And it's probably no accident that:

1) the mag that comes with that gun has a fairly weak spring and
2) it is rated for around 300fps.

I probably mixed things up after skimming through the posts...just seemed like McKee's post related a velocity increase to mag spring strength.

Most of the poor FPS air leaks that I've seen attributed to the magazine feed hole not being spaced out/aligned properly with the feed tube of the hopup unit. The hopup unit will be forced out of position and there'll be a resultant airleak at the nozzle/hopup rubber junction.

I definitely know that FPS values can be really low initially, especially in cold weather, as some warming/loosening up is needed. Ripping off a burst of full auto (BBs or not) before chrono'ing is a good idea if the temperatures are cool. But it should be just the first blast after the gun's been cold for a while...not at the start of each mag.

I'll reread this thread more carefully, thanks

The strong-mag-spring-weak-tappet-spring bug can happen in setups that have completely secured hopup units with good "nozzle-bucking kiss", so this is a new distinct issue that you can add to your catalog of infuriating problems with AEGs :)

Don't you just love AEGs?

After years of wrenching on them...frankly I got bored of them.

The only electric guns I would bother with are LMG/SAW's and PTW's.

Wow great insight MaciekA... Thanks dude. This makes sense. I knew hording away all those little parts like extra springs would come in handy. I shall report my results when I get around to this.

Son of a bitch. It worked.

MaciekA my good man.. you have earned this today.

http://files.sharenator.com/one_tril...244-174428.png

so you just increased the tension of the tappet plate spring and problem solved?
I'm having the same problem. 68 round mag doesn't feed properly untill theres only 50 or so rounds left in the mag, or if I only fill the mag to 50 rounds...

hmm having feeding issues similar to this and other threads ive searched... seems that i have to open the mech box and take a look ...


EDIT: in the process checked hopup rubber, bit permanent indent and small cracking where it the hopup nub fits into the rubber of the TM AK, changed with new G&P part, seems to feed fine now in semi, before almost every second shot was two bbs. In auto though ever 10 or so shots there is a blank fire, I am suspecting the tappet plate delay is not enough in the setup. For now its fine.