M4-1000 Problems

[pathfinderheli]

Hey folks... Looking for some guidance here. I have an M4-1000 that just had a small baffle strike. I run this on 2 different guns. One is on an 11.5 with a brake and the other is on a 14.5 (perm attached) Blackout. The 11.5 is fine. No apparent issues. On the 14.5 of Blackout the M4-1000 seems to wobble. It also shoots very loose. 4-5 notches loose... There is a definite wobble as well. Very noticeable and can be moved back and forth.

I've already sent this back to AAC to get the spring replaced.
I'm assuming the problem is with the Blackout Mount. I'm screwed since it is perm. attached. And I'm sure this has voided any warranty as well. I have an SDN-6 on order so eventually I could get the 18T blackout replaced with a 51T model but I was hoping to run the M4-1000 full time / dedicated to my 14.5.

Thoughts? Suggestions?

[ATCDoktor]

Reference your can backing off the mount, I have a 762SD that did the same thing (mines an 18T mounting interface like yours).

Here's a video, watch the tape at the 12 O'clock position on the cans muzzle.



Just like yours, AAC replaced the springs and it didn't help.

What I found helped was to continue to shoot the can on the suspect mount (checking the cans tightness every few rounds) and get as much carbon build up on the mount as possible (don't clean your can either).

The carbon build up will eventually tightens the cans hold on the mount.

The reason I say don't clean the can is that when I sent mine back to have the springs replaced, AAC cleaned the can and the condition (unscrewing from the mount under fire) was worse than when I sent it in, even with new springs

By the way, you can fix that endcap strike yourself with a brass punch and a few light taps with a hammer. Go lightly on the tapping and it'll be good as new in short order.

[TypeR632]

You could always send the upper in along with the can so they can check it out.

[pathfinderheli]

check out this video... You should be able to see the wobble here... This is with the suppressor installed as far as it will go. I can really crank it on there but then the spring is not between any of the teeth and it shoots loose.

[ATCDoktor]

As bad as mine was (the new springs did'nt engage the teeth on the mount just like you describe) there was never a wobble when my can was fully tightened on the mount.

That much wobble would only be manifested in my set up when the can was backed off a half turn.

In your last post you state:

I can really crank it on there but then the spring is not between any of the teeth and it shoots loose.

You need to tighten your can all the way down to where you can't tighten it anymore. If your shooting it with it wobbling like that you will keep getting endcap strikes.

For the sake of comparison, I have 4 18T mounts that I use my 762SD on and spring does not engage the teeth on any of them.

Not a click, not even a rub on the high points of the mounts, nothing.

I just kept shooting them (checking to insure the can was still tight) till the mounts and the threads on the can got filthy and now it threads on tight on all my mounts (even my 51T's on my AR's) and doesn't move.

I recommend you do the same.

[David Hineline]

Just face off the front shoulder of the flash hider until the spring catches the next notch, it does not take much.

[pathfinderheli]

I'm thinking of removing the springs and drilling out one of the holes where the spring is held and installing a set screw... I never really have the need to remove so this could be a cool solution.

[TypeR632]

Please don't drill a damn hole in your suppressor. Call AAC and send in your can and mount, or upper if it's pinned. Don't void a warranty by getting impatient. Make them make it right. Too much time and money goes into a nfa purchase.

[Ryo]

I wouldn't drill either. Just because you have a set screw:
1. It doesn't mean it will be aligned properly.
2. Hard to drill, but if you do go this route I recommend using a mill.
3. 100% void warranty

As for letting the can get dirty, it might help, but be warned that there's a possibility of the can seizing up on the threads. My buddy had his do that on his M4-2000 to get it tight.. but in the end of one of our Magpul Dynamics class, it was so tight that we accidentally unscrewed his flash hider from the barrel which was pinned to his barrel. We ended up getting a monkey wrench and a strap wrench to get the flash hider out of the suppressor. Wasn't a fun thing to do for him.

[TypeR632]

Lifetime warranty.

[krecon1]

What about mating your 18t can to a 51t mount? You could figure out where your springs lay when the can is fully seated onto the mount, then machine the 51t mount to have the springs fall into the notches when fully tight. The problem with the 18t mount is at best you get one spring to fall into a notch and the other resting on top. If you could time it to get both springs to fall into place your chances of it staying tight are greater. This may not be an option since your 18t is perm attached, but maybe for a futre build. I have (2) 18t 762SDs that are going this route when I get around to it.....