Originally Posted By Bullet_Magnet:
Ok I can tell you're a triggered fan boy so I'll break it down for you.
Gen 3 pmags have never dropped free. A fix was never offered. Magpul replaced them with gen 2 moe mags. My gen 2 20's never locked back so Magpul replaced those with gen 2's. KAC never offered a fix.
I've been in touch with kac several times about the gun failing to bolt hold open. They have only offered unsuccessful fixes.
I've seen inexpensivly built guns run my mags and can without any problem at all.
I didn't wake up one day and buy 50 pmags. I've accumulated them over the years and used with other guns.
Gen 3 mags have never dropped free under any circumstances. Gen 2 mags wont bolt hold open if using my suppressor...but plenty of other mags will. My exact combination works just fine in other guns.
As far as back pressure goes. Every single suppressor increases back pressure. The AAC is higher.
This is part of the reason I've been in touch with kac since I got the can in January 2017. I've used it with two separate kac uppers. I've spent hundred on buffers, springs, and the suppressed bolt carrier trying to chase a fix.
To me it's unacceptable that what amounts to a $3000 gun is this picky when plenty of cheapo guns don't have this problem.
So instead of talking about crying let's get back on track and try to come up with a fix here.
Not triggered, so let me break it down for you.
The fact that you're bringing up this issue AFTER 6 YEARS is suspicious at best. The fact that you're a self-proclaimed "long time KAC guy" but are just now making an issue of this further lends to the suspicion. We're kind of a tight-knit group in here, and I don't ever remember you being in forum before. So, welcome. There is a pinned post at the top of this forum with direct email accounts to KAC people you can contact if you're not satisfied with the answers KAC has given you so far.
Quick recap, so that I'm understanding you correctly:
Gun worked from day 1. Had to use Gen2 mags because the Gen3 mags were too tight and didn't drop free. COPY THAT, the Gen3 mags are know to be tight in some magwells. Magpul will give you instructions on where to file if they don't drop free. So, kind of a non-issue. But, they replaced them with the Gen 2 mags, and you were good to go.
You then swapped uppers and added a can, now the gun doesn't lock back on the Gen2 mags. Still locks back without the can though, am I right? If so, I'd say that's a suppressor issue, not a rifle issue. KAC guns are ported different, and run a proprietary length gas system, (I'm sure you knew that), so maybe that system isn't compatible with the AAC M4-2000, which is known for EXCESSIVE back pressure. Again, suppressor issue, not a gun issue. Maybe try running it with a KAC can if you know anyone that owns a NT4 or QDC. $5 says it runs like a champ.
Either way, why didn't you have this issues addressed immediately when you first bought the gun, or first hooked up the can? Coming in here several years afterwards and crying about it seems silly. There have been numerous threads recently about mags not functioning properly in the stripped lowers that KAC released earlier. Given that your gun has had issues "from day 1", yet you're just now posting in here, leads me to believe that you're trying to piggy-back on all those issues to get your gun "fixed", even though it's a completely unrelated issue.
The fact that you've isolated the problem down to one manufacturer's polymer magazines yet still want to blame the gun is laughable. IF EVERY OTHER MAGAZINE KNOWN TO MAN FUNCTIONS FINE IN YOUR GUN, THEN YOU HAVE A MAG PROBLEM, NOT A GUN PROBLEM. Maybe those Magpul mags are just ever-so-slightly too large for your magwell. For $100-$200 you could have a set of 20 OK/D&H/NHMTG/Brownells/whatever brand aluminum mags and have a 100% functioning rifle/suppressor/mag combo. That seems easier than popping in here and whipping up a shit storm.