Suppressors AAC 7.62 SDN-6 wiggleage?

F

freerangevoter

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Full Member
Minuteman
Jan 19, 2011
8
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North Idaho
#1
My new AAC SDN-6 can arrived a my Class-3 dealer yesterday
and I notice that when I twist it on hand tight to my new 51 tooth AAC Brakeout compensator I can loosen it about 1/2 a tooth before it catches the ratchet. At that point it stops unscrewing, but it wiggles. The instructions say, to turn it until it no longer turns, then "Without depressing the thumb pad on the ratchet latch, attempt to unscrew the Ratchet Mount silencer from the Blackout flash hider or muzzle brake. The silincer should not ratchet backward or jump teeth on the hider/muzzle brake, but a small amount of movement is normal and no cause for alarm."

So naturally, I'm alarmed! Any advice from guys that own the SDN-6?
 
#2
Re: AAC 7.62 SDN-6 wiggleage?

my SPR-M4 does the exact same thing, doesnt quite lock up solid, wants to roll back to the next tooth. accuracy with this can for me has been marginal at best. Im going to send it back to AAC with all my mounts to sort this out
 
#3
Re: AAC 7.62 SDN-6 wiggleage?

Thanks for the tip Tom. I have 2 additional Brakeout mounts that I will try the SDN on. If none of them index to the next tooth, I wonder if a guy might want to file the trailing edge of the ratchet to shorten it enough to let the next tooth slip by? I'll call AAC before doing any sort of mod and then post whatever I find.
 
#4
Re: AAC 7.62 SDN-6 wiggleage?

Well, I guess now is as good a time as any to express my frustration with the same issues. My 7.62SD 51T can does the same thing on a 5.56FH mount as the OP's --it doesn't lock up tight and backs off to lock into a tooth which allows it to wiggle on the mount. The can does lock up tight onto a 7.62FH mount that I have, and the results are very good-.5 moa accuracy, and it is repeatable on/off, with very good suppression.

This is the second 5.56 mount I have tried with the same results--the first mount was defective, resulting in an endcap strike, which AAC repaired under warranty, and then provided me with the current mount that does not lock up tight either.

I am ready to declare that AAC's mount is inherently flawed as it depends upon precise tolerances that they don't seem to be able to meet. With the way they currently machine these mounts, either the mount needs more teeth, or the can needs a second latch that is offset where one can lock up if the other does not. AAC seems to understand this as their new 300SD can has a 90 tooth mount that will allow for lockup over a wider range of tolerances with the threads than will the 51T mount. SWR's new Specwar mount also has finer teeth, and multiple latches to apparently avoid this.

I suppose I will have to test the can with multiple mounts to find one that will work, but that is a tedious process at best when I have multiple guns I want to suppress. I suppose I got lucky that 1 out of 3 works. I really don't know how to go about getting multiple mounts either without paying hundreds of dollars and trying to return the ones that don't work. I am going to ask AAC to supply me with them, so I guess I will see what happens.

Now I know why I should have ponied up for the Surefire, which does not have this issue.
 
#7
Re: AAC 7.62 SDN-6 wiggleage?

Yikes is right. The 762-SD's 18-tooth mount was less than optimal. Was hopeful the 51-tooth mount was the answer to this. Have they still have not gotten it right?

I have a Surefire Mini for my SBR. It locks up tight. No question.

I may sit this one out even though I had a 762-SDN-6 on order. Better yet, maybe it's time for my first thread-on can.
 
#9
Re: AAC 7.62 SDN-6 wiggleage?

Nothing worse than finding out your can is not working the way you need it too. It's such a commitment, and you never seem to find out just how good/ bad it is until after it is too late to do something.

I hope that you fellas get it all sorted out. AAC seems like a pretty big company that is very proud of their products. I would imagine that they will fix any issues someone has with their products.
 
#10
Re: AAC 7.62 SDN-6 wiggleage?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cluebat</div><div class="ubbcode-body">Yikes. I've got a 762-SDN-6 on order that I plan on using on my .308 and my AR, needless to say I'm hoping there is some resolution on this.. </div></div>

Same boat here
 
#11
Re: AAC 7.62 SDN-6 wiggleage?

here's another challange with their SPR-M4 can, mine is a 6.8spc model which only attaches correctly to the 5/8x24 mounts, not the 1/2x28 mounts. so forget about double-duty/ 5.56 on this setup. I like AAC's pistol cans alot, but I'll never buy another QD rifle can from them
 
#12
Re: AAC 7.62 SDN-6 wiggleage?

You guys are getting worked up over a non-issue. Yeah, if you have a defective mount that allows enough slop to result in a baffle strike, then you need to worry about that....frankly, I have to wonder about somebody that doesn't realize they have a problem when there is that much slop. My SPR-M4, on a half-dozen rifles and mounts, has some amount of play on all of them. It doesn't affect accuracy, as far as I can tell. My 18 tooth 762SD has a mount with more tolerance than the 51 tooth mounts, and doesn't seem to affect accuracy. It's not an issue. If you have an excessive amount of slop (see common sense here) then check things out before blowing the end out of your can. If it wiggles some, go shoot. The N6 is the best thing to hit the market in years. Drama, drama, drama...
 
#13
Re: AAC 7.62 SDN-6 wiggleage?

actually one of my mounts has a nice tight fit, no wiggle, no back and forth rocking or horizontal movement in only one position (#3) and it shoots good with this mount, too bad I have 3 others that are sloppy as shit not including the 1/2x28 mounts that wont work at all
 
#14
Re: AAC 7.62 SDN-6 wiggleage?

I have a M4-2K and it is the same as you are describing. On one mount it locks up tight and there is no backing off. On the other 4 or 5 mounts there is different degrees of backing off. The worst is just about a full ratchet or about (360deg/51t= 7.059 degree)

I don't think that this affects accuracy a whole lot, but I think that it has to a little bit anyways. I just swapped the best one onto my Bolt gun and called it a day.

The system is not perfect for precision, but a good compromise. I have a N-6 on the way too and feel that this will work for me.
 
#15
Re: AAC 7.62 SDN-6 wiggleage?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chainring</div><div class="ubbcode-body">You guys are getting worked up over a non-issue. Yeah, if you have a defective mount that allows enough slop to result in a baffle strike, then you need to worry about that....frankly, I have to wonder about somebody that doesn't realize they have a problem when there is that much slop. My SPR-M4, on a half-dozen rifles and mounts, has some amount of play on all of them. It doesn't affect accuracy, as far as I can tell. My 18 tooth 762SD has a mount with more tolerance than the 51 tooth mounts, and doesn't seem to affect accuracy. It's not an issue. If you have an excessive amount of slop (see common sense here) then check things out before blowing the end out of your can. If it wiggles some, go shoot. The N6 is the best thing to hit the market in years. Drama, drama, drama... </div></div>

It does affect accuracy. Thread on cans do not "wiggle" when tight, nor do other mounting systems, and neither should these.

I have already had one endcap strike--strange considering the hole in the endcap is ~.380" and the bullet is .223"!--and it appears that there may be enough play for it to happen again. But I am not going to use the mount that is loose because I don't want my can damaged again. Oh, and before you go there, my barrels checked out for concentricity-the mount was the problem.

Wonder all you want, but AAC warrantied the repair, and stated their mount was made wrong. Considering all the problems with the 18T mounts, you are one of the lucky ones it seems. Are you saying loose cans are acceptable? How loose? What is the standard? How does the end user measure it?

This is not made up drama, it's a real issue.
 
#16
Re: AAC 7.62 SDN-6 wiggleage?

First post and all, but...

This is EASY to fix. I fit all my mounts to my M4-2000 and
SDN-6.

For the 5/8-24 Blackout:

1) Cram a 3/8" wooden dowel in from the prong end.
2) Chuck other end of dowel into low speed drill press.
3) Beveled surface facing up @ you just downrange from teeth
or just behind threads is surface to be ground.
4) Use fine or medium EZLap, magnifying glasses, and a
sharpee to carefully grind back that edge.
5) Grind, check fit , grind 'till she locks up @ your desired
torque or tightness - I'm low round count per session,
not worried about can getting stuck on gun, and set mine up
fairly tight.

If your can is already loose, and you're already close to the next tooth, this takes 2 mins. If you need to advance 3/4 of the notch, then it takes some time.

Works GREAT for me. Accuracy improved, my POI shifts are nil,
and it turns a rattling "suboptimal accessory" into what it should have been in the first place.

BayouRobert
 
#17
Re: AAC 7.62 SDN-6 wiggleage?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BayouRobert</div><div class="ubbcode-body">First post and all, but...

This is EASY to fix. I fit all my mounts to my M4-2000 and
SDN-6.

For the 5/8-24 Blackout:

1) Cram a 3/8" wooden dowel in from the prong end.
2) Chuck other end of dowel into low speed drill press.
3) Beveled surface facing up @ you just downrange from teeth
or just behind threads is surface to be ground.
4) Use fine or medium EZLap, magnifying glasses, and a
sharpee to carefully grind back that edge.
5) Grind, check fit , grind 'till she locks up @ your desired
torque or tightness - I'm low round count per session,
not worried about can getting stuck on gun, and set mine up
fairly tight.

If your can is already loose, and you're already close to the next tooth, this takes 2 mins. If you need to advance 3/4 of the notch, then it takes some time.

Works GREAT for me. Accuracy improved, my POI shifts are nil,
and it turns a rattling "suboptimal accessory" into what it should have been in the first place.

BayouRobert
</div></div>

Ummmmm.....hows about an instructional video Robert?
grin.gif
 
#18
Re: AAC 7.62 SDN-6 wiggleage?

I was having major accuracy issues. I found that after 3 rounds of sub MOA the can would drop back in the groove n wiggle. Accuracy was at best 6 MOA. So, a bud n I used a lathe to polish back the leading edge of the adaptor on one mount. That one fits as tight as a can be now. Accuracy is sub MOA out of a SASS. I have 5 other adaptors to adjust next.
 
#20
Re: AAC 7.62 SDN-6 wiggleage?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chainring</div><div class="ubbcode-body">You guys are getting worked up over a non-issue. Yeah, if you have a defective mount that allows enough slop to result in a baffle strike, then you need to worry about that....frankly, I have to wonder about somebody that doesn't realize they have a problem when there is that much slop. My SPR-M4, on a half-dozen rifles and mounts, has some amount of play on all of them. It doesn't affect accuracy, as far as I can tell. My 18 tooth 762SD has a mount with more tolerance than the 51 tooth mounts, and doesn't seem to affect accuracy. It's not an issue. If you have an excessive amount of slop (see common sense here) then check things out before blowing the end out of your can. If it wiggles some, go shoot. The N6 is the best thing to hit the market in years. Drama, drama, drama... </div></div>

Agreed. Less complaining and more shooting!
 
#22
Re: AAC 7.62 SDN-6 wiggleage?

Try making sure the mount is nice and clean and see if it will go the extra notch. Can be a pain in the ass keeping it that clean, but I have seen a couple grains of unburned powder or grit cause the can to not get that last notch or two.
 
#23
Re: AAC 7.62 SDN-6 wiggleage?

With the adjustment post by BR, I'm having a hard time understanding exactly what you're stating. Are you saying grind the muzzle end of the adapter down, or the threading on the muzzle end?
 
#24
Re: AAC 7.62 SDN-6 wiggleage?

Neither...If you look @ your blackout from the side.... from front to rear...you see...

1)Prongs
2)Flat/plain old round area
3)Suppressor threads
4)Forward (toward enemy) beveled edge
5)Rachet teeth
6)Rearward (toward shooter) beveled edge
7)Etc.

#4 above is the surface in question. You want to polish it back toward the shooter.

If your suppressor fit is sloppy and you think you are almost to the next notch, then "grind" is actually way too strong a word. Just carefully work/polish that edge as you spin the flash hider with lathe or as above with low speed drill press
using a fine EzeLap (Brownells or hardware store).

Check fit frequently as you go. If you get greedy and overshoot your sweet spot, then you'll really have to grind your way to the NEXT notch.

It's not some super critical thing, but avoid changing the pitch of that surface or edge, as you go. Reblack the edge @ each "fit check" with a Sharpee or similar, so you can tell what you're doing as you polish.

I set mine up TIGHT, so that the first time I screw the suppressor on it seems like a few foot lbs are needed. If it remains that tight, I lap it on/off with some moly paste and am then good to go.

Because of the angle that the latch grabs the teeth (on MY suppressors), it will never be hard to UNLATCH the suppressor - no matter how tightly it is applied to the mount. May be hard to UNSCREW it...hence, the moly lap.

Once you play with doing this once,then you'll do all your mounts. It's quick and simple - really no way to screw it up.

BayouRobert

 
#26
Re: AAC 7.62 SDN-6 wiggleage?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: BayouRobert</div><div class="ubbcode-body">Neither...If you look @ your blackout from the side.... from front to rear...you see...

1)Prongs
2)Flat/plain old round area
3)Suppressor threads
4)Forward (toward enemy) beveled edge
5)Rachet teeth
6)Rearward (toward shooter) beveled edge
7)Etc.

#4 above is the surface in question. You want to polish it back toward the shooter.

If your suppressor fit is sloppy and you think you are almost to the next notch, then "grind" is actually way too strong a word. Just carefully work/polish that edge as you spin the flash hider with lathe or as above with low speed drill press
using a fine EzeLap (Brownells or hardware store).

Check fit frequently as you go. If you get greedy and overshoot your sweet spot, then you'll really have to grind your way to the NEXT notch.

It's not some super critical thing, but avoid changing the pitch of that surface or edge, as you go. Reblack the edge @ each "fit check" with a Sharpee or similar, so you can tell what you're doing as you polish.

I set mine up TIGHT, so that the first time I screw the suppressor on it seems like a few foot lbs are needed. If it remains that tight, I lap it on/off with some moly paste and am then good to go.

Because of the angle that the latch grabs the teeth (on MY suppressors), it will never be hard to UNLATCH the suppressor - no matter how tightly it is applied to the mount. May be hard to UNSCREW it...hence, the moly lap.

Once you play with doing this once,then you'll do all your mounts. It's quick and simple - really no way to screw it up.

BayouRobert

</div></div>

Thanks, going to try it this week. Thanks for repeating to go easy on the threads--I'll update with results.
 
#27
Re: AAC 7.62 SDN-6 wiggleage?

Don't touch the THREADS...it's the angled flat edge just downrange from the teeth that the suppressor latch grabs. It's just behind the threads.

Look inside your suppressor, and you'll see a mirror-image shiny machined beveled edge that the mount butts up against as the suppressor seats when fully screwed on.

All clear??
 
#32
Re: AAC 7.62 SDN-6 wiggleage?

Oh, it works. Don't get on here and troll out.

All the mounts for the N6, SD, and M4-2000 are the same. Sometime you luck out and the lockup is right on the nose and fairly tight. Sometimes the mount bottoms right before another tooth falls under the latch, and it backs off a bit and allows the can to wiggle ever so slightly. Most people don't worry about it.

For those that DO care, this thread shows them one method of allowing the can to bottom out a little later and catch that next tooth in order to take out some play.

You are supposed to contribute to the forum, not muck around.
 
#34
Re: AAC 7.62 SDN-6 wiggleage?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: chainring</div><div class="ubbcode-body">Oh, it works. Don't get on here and troll out.

All the mounts for the N6, SD, and M4-2000 are the same. Sometime you luck out and the lockup is right on the nose and fairly tight. Sometimes the mount bottoms right before another tooth falls under the latch, and it backs off a bit and allows the can to wiggle ever so slightly. Most people don't worry about it.

For those that DO care, this thread shows them one method of allowing the can to bottom out a little later and catch that next tooth in order to take out some play.

You are supposed to contribute to the forum, not muck around. </div></div>

If customers were getting my product and had to do machining operations to make them work, I'd be getting character assassinated for it.

I do think wobble is tolerable on a 5.56 can. That's based on the very expensive KAC M4-QD [most successful suppressor in military history to date as far as I know] having some play. The large bore tolerance most 5.56 QD options have helps to reduce negative ballistic effects and M855 in an M4 is a 3MOA combination in most cases to begin with- meaning that precision 5.56 platforms are a niche market not the lions share of it.

The 7.62mm suppressors often go on guns that guys expect to shoot sub MOA, so play isn't tolerable on them.

That one tooth and 7 degrees factored to about .034" of front end wobble based on some calculations I did. That would be .044 on the longer 7.62SD, so the working bore is .336 at the front end (one tooth loose senario). It is 30% longer than a standard thread mount 5.56 can for which a .275" bore is perfectly ideal and safe [IMO] so .290 should have been fine- making a 5.56mm endcap strike on a 7.62SD length suppressor with a working bore of .336 at the front cap, an unexplained phenomenon.
 
#35
Re: AAC 7.62 SDN-6 wiggleage?

Machining operations?

I would not classify a drill, a dowel rod, sand paper and 20 minutes of your time a serious undertaking. This method works and I have done it in a lathe before, its quick and easy and helps quite a bit.
 
#39
Re: AAC 7.62 SDN-6 wiggleage?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Griffin Armament</div><div class="ubbcode-body">It depends on how you look at it. After lapping a $99 mount, you have no finish on that part of the mount and have 20 minutes of labor in it.

It's not the world, but I wouldn't suggest it's muckraking to say it's not ideal. </div></div>

AND, I have spent WAAAY more than 20 minutes on mine with an EZ Lap, and it's still about 1/2 tooth away from locking in. The steel surface is very hard, which is nice for durability, but not so cool for DIY operations.

I am very fortunate that my 7.62 mount locks up nice and tight, and the gun's accuracy increases with the can attached, but luck is not a design feature I look for.
 
#40
Re: AAC 7.62 SDN-6 wiggleage?

Well, I have my 762-SD-N6 in hand now and I just went out and shot about 200 rounds of Remington 220gr subsonic ammo thru the 9" SBR from AAC.

The rifle runs like a top and the suppressor did not affect cycling or accuracy. It locks up fairly tight, according to Mike Mers at AAC some wiggle is fine but more then an 1/18 of an inch is a bad mount to can fitment and they will resolve it for you.

The can is very nice. CRAZY quiet! The impact of the round on steel at 40 yards is more loud then the rifle functioning!
 
#41
Re: AAC 7.62 SDN-6 wiggleage?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KYS338</div><div class="ubbcode-body">Well, I have my 762-SD-N6 in hand now and I just went out and shot about 200 rounds of Remington 220gr subsonic ammo thru the 9" SBR from AAC.

The rifle runs like a top and the suppressor did not affect cycling or accuracy. It locks up fairly tight, according to Mike Mers at AAC some wiggle is fine but more then an 1/18 of an inch is a bad mount to can fitment and they will resolve it for you.

The can is very nice. CRAZY quiet! The impact of the round on steel at 40 yards is more loud then the rifle functioning! </div></div>

Good to hear! Figured AAC would take care of the problem. Can't wait to get mine, unfortunately my form 4 just went out this week.
 
#43
Re: AAC 7.62 SDN-6 wiggleage?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: magnum_99</div><div class="ubbcode-body">....... but luck is not a design feature I look for. </div></div>

ROFL, that is a quotable quote!
 
#44
Re: AAC 7.62 SDN-6 wiggleage?

My VERY accurate Noveske 6.8 10.5 CQB would not shoot worth
a damn suppressed until I "fit" the M4-2000 and mount.

Noveske had torqued the Blackout on so tight that we gave
up on removing it (torched, froze, etc), so....

1) Stick 6 inch long 1" dowel in rear of AR upper
2) Stick 4 inch long 3/8" dowel in muzzle/prong end of Blackout
3) Place the above in a set of greased brass v-blocks
4) Use hand drill to turn assembly via 3/8" dowel chucked into
drill and polish Blackout as described
5) Need 2 helpers with steady/patient hands to do this

End result...Shoot Ipsc torso's @ 700 with essentially same
POI,suppressor on or off. Might move 1/2 min here or there, but I mean its a 10.5 incher @ 700 yds, so who cares. Hits 12-14
out of 15 round mag for me on perfect mornings with no wind.
 
#46
Re: AAC 7.62 SDN-6 wiggleage?

Downrange-facing narrow beveled edge (ie edge that is @ a slant, not vertical and not horizontal) just downrange of teeth and just behind suppressor threads. You want to polish that bevel back toward the shooter just a bit, so the suppressor screws on a bit further to lock tightly on the next tooth.

The beveled edge is the "shoulder" that the corresponding "shoulder" inside the suppressor butts up against when you screw it on just as far as it will go. Stick finger in butt end of suppressor, and you'll feel said shoulder just beyond threads.

I gotta learn to post vids or pics. Sorry. PM if needed.
 
#47
Re: AAC 7.62 SDN-6 wiggleage?

I believe he's talking about here, correct me if I'm wrong:

fh_51tbevel.jpg


So do you keep the bevel at the same angle, and not modified the 90 degree edge?

Your NOveske 6.8 10.5 CQB job must have been one interesting job. I might have to do something similar since mine is pinned on. Should be interesting..
 
#48
Re: AAC 7.62 SDN-6 wiggleage?

YES, that's it. Thanks for posting a picture. Don't change the pitch of the bevel. Just polish it back a bit. You do not need to alter any other edge or surface. Thanks again.
 
#49
Re: AAC 7.62 SDN-6 wiggleage?

RYO, when we did the upper in the v-blocks we made very little progress for about an hour. We just couldn't get enough pressure on the blackout with the ezelap to cut any steel. Finally made that 1" dowel real tight in the upper with a few wraps of tape and then let the butt end of the 1" dowel ride against the shop wall as we turned the upper with the drill. The 3rd man in the operation kept it stable at the wall end. One driller, one cutter, one stabilizer.
 
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