Factory DDMK18 upper and AAC 51T muzzle brake question....

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Whitebrad25
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Factory DDMK18 upper and AAC 51T muzzle brake question....

Post by Whitebrad25 »

I am currently waiting on my Form 1 (I have awhile...) and I am obviously looking at things to keep myself busy.....like another Form 4!

I bought a Factory DDMK18 upper to go with my Factory DD lower (from my M4V5) and, as we all know, the factory DDMK18 uppers have a 10.3" barrel....they sit very, VERY close to the RIS II rail...I have taken some quick pictures to illustrate my concerns....I haven't bought a can yet so I am not in this too deep...I have seen and been told that Surefire has a combination that WILL work (because of how their can mounts to their FH)....but I am not in love with Surefire...they change designs more often than I care for and they are expensive, more so than what I would consider to be better cans.


I am preferably trying to get this to work with an M4-2000....or an SDN6. I have an AAC 51T Muzzle Brake which will be replacing the proprietary DD A2 flash hider. In all pictures below the shoulder of the barrel/threads seem to be under (just slightly) the rail....I cannot seem to picture how this would work. In short, I don't have the tools to dick everything up and take on and off the flash hiders so I am trying to get a good idea of what I am dealing with before I jump right in. The big thing is that I am not sure how low either can sits on the specified mount (AAC 51T Muzzle Brake). I know the shoulder seems to be slightly under the rail but the brake will obviously fit...I'd like to be shooting with a can at least 80% of the time...



ANY HELP IS APPRECIATED AND PICTURES ARE A HUGE PLUS!










Here are some quick pictures to illustrate my issue with the 10.3" barrel...

I didn't do anything with my lighting so the focus is not that great...when I place the AAC 51T mount above the DDA2 you can't really tell but the flash hiders are not equal in starting point (the AAC 51T looks to be stopped by the rail....). This may OR may not be a problem....I am not sure how low an M4-2000 or SDN6, for example, go down on these mounts.

Image

Image

Image


And here is the same thing above just with better lighting....it is important to focus on the shoulder that the brake should rest against...it appears to clearly sit just behind the rail (hundredths of an inch if that much..).

Image

Image

Image

Image


Excuse the dirty AAC 51T brake :mrgreen:
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Bendersquint
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by Bendersquint »

You need a spacer behind it to work.
Whitebrad25
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by Whitebrad25 »

Any info on the spacer? How will this ensure the mount of the Brake and can are GTG?

Any examples/links...


I heard a spacer mentioned in a thread but no one gave any details about it....


I know some people use washer (I have some crush washers) but I have also read (could be bs) that the amount needed would not ensure a solid attachment... :?:
Whitebrad25
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by Whitebrad25 »

Post 2 in this thread is sort of hitting at my concerns....

viewtopic.php?f=86&t=92976


I am not sure if that much space will allow for a safe mount and in his other point, he mentions a "skirt" behind the teeth....does mine have this? I do see a slight 'skirt' like section....
66427vette
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by 66427vette »

Get a AAC or sure fire spacer kit.
Whitebrad25
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by Whitebrad25 »

Do you guys mean a shim kit? Or a fixed spacer? I assume you mean the shim kit....even still, how can I assure everything is going to be locked up and solid?


Are there really no current owners of this set up on this forum?
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Bendersquint
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by Bendersquint »

Whitebrad25 wrote:Do you guys mean a shim kit? Or a fixed spacer? I assume you mean the shim kit....even still, how can I assure everything is going to be locked up and solid?


Are there really no current owners of this set up on this forum?

The shim kit is the one you want if you cant get a fullsize spacer for your need. We were going to do a run of them but there appeared to be little interest so we canx the idea.

It will lock up just fine, check and recheck then torque in place and drive on.
Whitebrad25
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by Whitebrad25 »

What kind of spacer?


I have a shim kit.....

When I google for spacers I see results for pistol cans... https://www.google.com/#hl=en&tbo=d&out ... 66&bih=643
66427vette
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by 66427vette »

That will work. We had to raid 2 kits last time we did one.
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by sarthree »

two shim kits worked...though I switched it up for the blackout. I wish I would have stayed.
Whitebrad25
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by Whitebrad25 »

Two shim kits as in the entire kit?? My pack of shims has 6 inside? One full shim kit totals to .095 and that seems excessive.....it would be visible as well....kinda hoping for a better solution than stacking 12 shims or even 6 shims for that matter...
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Bendersquint
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by Bendersquint »

Whitebrad25 wrote:Two shim kits as in the entire kit?? My pack of shims has 6 inside? One full shim kit totals to .095 and that seems excessive.....it would be visible as well....kinda hoping for a better solution than stacking 12 shims or even 6 shims for that matter...
2 other solutions.

1 - Buy another barrel the correct length.

2 - Buy another suppressor with a different mounting system.
Whitebrad25
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by Whitebrad25 »

Bendersquint wrote:
Whitebrad25 wrote:Two shim kits as in the entire kit?? My pack of shims has 6 inside? One full shim kit totals to .095 and that seems excessive.....it would be visible as well....kinda hoping for a better solution than stacking 12 shims or even 6 shims for that matter...
2 other solutions.

1 - Buy another barrel the correct length.

2 - Buy another suppressor with a different mounting system.

I bought a factory upper....so buying a 'correct' length barrel is an odd suggestion.


I will probably have to go into the Surefire system......


I have seen pictures of a Factory DDMK18 upper and an SDN6 used...with an AAC 51T brake...
66427vette
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by 66427vette »

We used two of the thickest shims one from each kit. Use as few as possible . If you can't figure it out take it to your dealer if is any good he will know what you need.
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by 66427vette »

Or if you know someone with a lathe have them make a spacer .
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by bigbigpig »

You could use something like this:
http://www.thesilencerstore.com/index.p ... ducts_id=1

I think it's .25" but I'm not sure. Contact the seller (John Titsworth) to get details on it.

Alternatively you could get a different rail if you didn't care about keeping the MK18 authentic. The DD AR LITE 9.0 is 1/2" shorter so you wouldn't have to worry about spacing out the 51T.
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by Bendersquint »

Whitebrad25 wrote:
Bendersquint wrote:
Whitebrad25 wrote:Two shim kits as in the entire kit?? My pack of shims has 6 inside? One full shim kit totals to .095 and that seems excessive.....it would be visible as well....kinda hoping for a better solution than stacking 12 shims or even 6 shims for that matter...
2 other solutions.

1 - Buy another barrel the correct length.

2 - Buy another suppressor with a different mounting system.

I bought a factory upper....so buying a 'correct' length barrel is an odd suggestion.


I will probably have to go into the Surefire system......


I have seen pictures of a Factory DDMK18 upper and an SDN6 used...with an AAC 51T brake...
Correct length for the system you are trying to create is what I meant. If it was designed from the factory for that system this conversation wouldn't exist. ;)

That SDN6 had a spacer on it(at least the pictures I have seen).
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JasonM
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by JasonM »

Another option for you is to use an AAC BRAKEOUT mount versus the brake. The BRAKEOUT has a "skirt" behind the ratchet teeth that gives you the needed rail clearance.

As far as authentic clones, the largest MIL MK18 user group also uses AAC cans and they run the BLACKOUT flash hider.
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sarthree
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by sarthree »

Whitebrad25 wrote:Two shim kits as in the entire kit?? My pack of shims has 6 inside? One full shim kit totals to .095 and that seems excessive.....it would be visible as well....kinda hoping for a better solution than stacking 12 shims or even 6 shims for that matter...
Two entire kits will make it work. Hopefully some of the others will come up with some good ideas. The most important thing is that it has to be very tight in tolerance. Dear god don't use a crush washer.
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by Bendersquint »

sarthree wrote:
Whitebrad25 wrote:Two shim kits as in the entire kit?? My pack of shims has 6 inside? One full shim kit totals to .095 and that seems excessive.....it would be visible as well....kinda hoping for a better solution than stacking 12 shims or even 6 shims for that matter...
Two entire kits will make it work. Hopefully some of the others will come up with some good ideas. The most important thing is that it has to be very tight in tolerance. Dear god don't use a crush washer.
Or a spring or wave washer.
Whitebrad25
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by Whitebrad25 »

I cannot attest to the validity of this but a member on another forum suggested two of the larger shims (.03) and said it should work...?
66427vette
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by 66427vette »

Plus what ever you neet to time the mount. I believe the surefire shims were a little thicker. Mix and match to see what works it is very simple.
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by 66427vette »

You could always get crazy and get out a set of calipers.
Whitebrad25
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by Whitebrad25 »

66427vette wrote:You could always get crazy and get out a set of calipers.


As mentioned I don't have it installed yet (also don't have calipers or the time to get any). I am 6 months at least waiting on my stamp so I am trying to gather the info now versus later. I am not in a rush I just figured more people would have the set up and could comment from experience.
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Re: Factory DDMK18 upper and AAC 51T muzzle brake question..

Post by 66427vette »

Pm me your phone number I shoot you a text pic .
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