I’ve purchased an AAC M4-2000 for use on a 14.5" DD midlength with a pinned 51T Brakeout Comp., H buffer. Still waiting on the ATF after 4 months. All indications are I have at least another month to wait.
I had a chance to use a friends M4-2000 this past weekend and put 50-60 rounds of IMI M193 through it. Couple of things I noticed.
It appears to be overgassed with the suppressor mounted. I suspected this may happen. Ejecting brass at one o’clock instead of the normal four o’clock unsuppressed.
It was filthy as hell. Granted, we had just returned from a 150rd carbine match and the AR was not perfectly clean, but this caught me by surprise. Carbon coated in the upper receiver and an inch down the magazine like it had been used as a stovepipe.
Is it safe to assume that the filth is a side effect of the overgassing?
Everything I’ve read leads me to believe that this is caused by the overgassed effect and the bolt is unlocking prematurely. Is this correct?
Is a heavier buffer the only option available to me? Or, is there a combination of options to consider? I would like for this AR to run reliably unsuppressed as well.
Anyone have a similar setup that wants to offer options on improving these two issues? I know I can’t possibly expect to completly mitigate either one, but surely there is room for improvement.
Filthy is just part of the charm when it comes to shooting ARs suppressed. And yes, you are getting higher gas blowback with the can attached. Suppressors are notorious for altering the timing of ARs that work fine unsuppressed, which is why there are products out there like Noveske’s Switchblock.
You can certainly try the heavier buffer. You can also swap in a Sprinco red extra-power spring. Or, if you are able, you can swap your gas block for a Noveske Switchblock - Noveske makes a clamp-on version specifically for 14.5" midlength barrels. You’ll have to run an FSP version of a longer rail, or just go with a midlength handguard of some type.
You can change the buffer or recoil spring, convert to switchblock or buy a barrel with a smaller diameter gas port. Like others have already said though, when firing suppressed, it’s going to get dirty. Most the gas that is supposed to be blown out the front of the gun is now being forced back down the barrel because its the easiest place to go. Seems there is no way to prevent it. Buy the can, buy some rounds, shoot the piss out of it. Enjoy the suppressor, they are so much fun. Oh and I may be the only one experiencing this, but I have noticed increased wear on the cam pin, I believe from firing suppressed. Bolt carrier moving rearward with more force is what I believe I read. I could be wrong though.
Nice video Mark. The ROF is very noticeable between the two as is where the cases are ejected.
Sounds like I’ll be getting alittle dirty. I can live with that.
Wish I had thought of the switchblock when I was building this weapon. I knew they existed. Just didn’t come to mind. I might could swing the cost of the switchblock right now but, combine that with having to get a new rail, it’s not doable for me right now. I wonder if anyone has modified a typical rail, cut out a portion of the top front, to install a switchblock? Or, am I thinking too far outside the box?
Here is the weapon in question. I really would be hesitant to cut on this Centurion rail.
In lieu of the switchblock, it seems the only other options are a combination of buffers and springs.
This rifle currently has a H buffer and a Tactical Springs CS Blue Spring.
Mark what buffer / spring combo are you using in the video?
Someone here cut their rail on top to make room for the switchblock, it was one of the Industry Professionals or SMEs. It looked nicely done. I am trying to find it now, but its evading me.
All AR’s (unless SPECIFICALLY built for suppressed us) are over gassed as the can generates nearly double the back pressure.
It was filthy as hell. Granted, we had just returned from a 150rd carbine match and the AR was not perfectly clean, but this caught me by surprise. Carbon coated in the upper receiver and an inch down the magazine like it had been used as a stovepipe.
Normal. Again, the only way to fix this is to build a gun from the ground up that is dedicated for suppressed use.
Is a heavier buffer the only option available to me? Or, is there a combination of options to consider? I would like for this AR to run reliably unsuppressed as well.
No. Look at going to the LMT Enhanced Carrier, H2 buffer and Tactical SpringCo BLUE buffer spring. This will slow things down.
Someone did a nice job on that. The switchblock is out though. After looking at that pic it reminded me that my muzzle device is pinned and the options in order to go there are too much hassle and expense.
Grant - On the LMT Enhanced Carrier. Do you have to use the LMT bolt with the enhanced carrier or will a regular bolt work?
Too bad that G&R Tactical outfit doesn’t have the carrier, H3 or the spring in stock. I could save on shipping with one stop shopping.
You can use a standard bolt with the LMT Enhanced BC. We have these in stock and have the Tac Spring CO Blue buffer spring in stock. Would go with the H2 buffer and not the H3 (also in stock).
On the handguard - would it be worth considering the C4 Middy Cutout rail? Leaves a bit of open space up towards the front, but if cutting on a rail is something you’d like to avoid, you wouldn’t be eating quite as much expense on that, especially if you found somebody to just trade rails straight up with.
