Suppressors AAC 7.62 SDN-6 wiggleage?

Here's what I'm using now...with some pictures included.
020 Kalrez Perfluoroelastomer O-Ring, 4079 Compound, 75A Durometer, Round, Black, 7/8" ID, 1" OD, 1/16" Width (Pack of 1) $40.73 on Amazon
Kalrez O-ring-1.jpgKalrez O-ring-3.jpgKalrez O-ring-2.jpg
 

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Holy crap, $40 for a single o-ring? How long does it last before needing to be replaced?

That o-ring should work great if you're firing it on a bolt gun. I might pick one up.

However I'd avoid it on a rig with a high rate of fire. Dupont only tested the material to 600*F. It can withstand higher temperatures in short bursts (although it did not define what temp that is or how long those bursts are) but cans usually maintain their heat for a long time. Still, a slow fire bolt gun in a .308 caliber shouldn't get much hotter than 600 degrees (at least not for very long)

http://www2.dupont.com/Kalrez/en_US/pfo/assets/downloads/Kalrez 4079AMS.pdf
 
This o-ring idea got me to thinking. What about using an assortment of very thin stainless shims, split like the gas rings on an AR bolt, and then threading them down onto the mount? The can would tighten and likely compress the shim to mate flat against the beveled mount and still retain concentricity and preventing excess runout. Using ones longer that would overlap and then filing them square once fitted may be necessary, I don't know. I reckon one with an ID just wide enough to fit the mount, and an OD about half or so what would be necessary to cover half or just over that on the beveled surface would work, with thickness depending.

Anyone have any ideas on this? Or possibly a source for them so I can try 'em out? What do you think?
 
I polished one that locks up tight too. Like you'd want it to. It was a pain in the ass by hand, took forever and had to stop constantly to make sure I was keeping it straight. I wasn't far to the next latch. For the .308 I'm afraid to use, there's too much material to remove by hand and be sure it's perfect. Not a simple lapping and polishing job.

A lathe or drill press would be ideal, and if there's a lot of wiggle but you're far from the next latch that's what you'll need IMO. One day I'll get around to it. This is the best way to do it really, have each one custom mounted to the damn can. You can look for runout that way too.

I looked at those washers and springs. I thought about springs too, but all of those are too thick it seems. The width of spacer you'd need is miniscule, like hundredths/thousandths of an inch at most, hence the idea I had of using a split shim (so it'll fit over the threading but stay snug against the mount) not come off, easily mesh between the can and the mount, and be just wide enough to provide positive lockup at the very next latch. It also has to be narrow enough to not interfere with the teeth or latch. I really think this would work, a simple solution that wouldn't change anything to the system, but I haven't one to try. It may be a nice stopgap until one can get it modified right.
 
I've owned an AAC SCAR-h since 2009, and never have figured out how to correct for the 1 MOA zero shift I get after removing/re-attaching the can, even with a Blackout mount fitted using BR's method of obtaining a good tight fit. SCARs are different from the SDN-6 in that they have triple pitch threads, and index numbers engraved around the circumference of the rear of the can. This is supposed to allow you to experiment to find the most accurate index position when attaching the can, though I never really saw enough difference in groups for this to be any advantage for me - and I get the zero shift whether I re-attach using the same index number at 12:00 or not.

Finally gave up on figuring out this issue, and bought a TBAC 30BA. Have BA mounts on four bbls - 2 DTA SRS & 2 conventional rifles - and have never had the zero shift that plagued the SCAR. Was never crazy about the SCAR's overlap mounts either, so recently traded it for a SF 7.62 SOCOM - now all I have to do is be patient for 9+months while the SF form 4 goes through the process....
 
My SDN-6 generally opens up about 1MOA too. On the Grendel, the one I got nice and tight, it opens up from .33MOA to about 1MOA total, so that's liveable. The next can for that rifle, when that barrel wears out, will be a thread on for sure and maximized for accuracy.

The weight of the can is capable of bringing down the POI I understand, particularly with light barrels like my M4's. But if it isn't timed (and some folks dispute whether this is necessary or not, and most cans aren't timed as it is) it can be all over the place vs. just a vertical displacement from the usual POI. So I had my .50BMG can, something I expect to use at very long range, timed. When I get another .30 can, likely a thread on, I'll likely get it timed too. For the price of timing it, it's worth the peace of mind I feel.

You know, the 51T DID look like a great QD mount or I never would have gotten it. I know better now. I WILL NOT buy a QD mount that I can't inspect first, and I won't buy another AAC regardless. I learned my lesson here with AAC.
 
Well, after 5 mounts I think I have one that will work with my 762SDN6. My gunsmith/SOT had a few on hand and we tried them all until we found one that was really close to engaging the next tooth, and then barely took of some material off of the mount, as others have done in this thread. We'll see if it stays tight as I shoot. Tried emailing Brent, Mike Mers, John Hollister, and ALL of them ignored my emails. Ive exchanged emails with John Hollister in the past and he usually emailed me back the same day. My NFA dealer wont sell AAC QD cans anymore because so many of his customers have had issues, and him being a nice guy would replace their mounts until they found one that would work.
 
This thread kinda kicks me in the junk since order one in Dec and should be able to pick up at the end of the month. I know there are lemons and stuff that is on the edge of being out of spec but still in spec (on the loose side) but still worries the hell out of me. No one wants a limp dick...no one wants a wiggle suppressor.
 
Yeah, kinda, but I'm gonna stick with stoning by hand using a small whetstone and machinist blue or a sharpie on the ones that are really close, and trying again to trade back this one that's REALLY bad or else taking it to a shop to have it done right. Removal of too much material and you risk increasing run out without a lathe and proper tools, even if it doesn't seem like much material, one tooth's worth actually is. You want contact with the entire 360deg. of that bevel when done.

For future mount purchases, I'll be taking my can to the dealer to have one fitted, to just try 'em out until I find one that clicks or just damn near does so I can stone it tight. And the only reason I'll be doing this is because since I already have the can, and the can itself is a damn nice piece --barring a strike of some kind, it'll likely outlast me-- so I want a few mounts on hand when these crap out so it'll still function, because when AAC abandons it, I'm betting they'll do away with it for good.

For future rifles, and for the new barrels I have on order with Satern, I'll be getting a new can from somebody who isn't AAC; I'm not playing this fucking game again with another Satern barrel and hoping for the best with these shitty mounts. I've said I'd rather get 2 thread ons vs. one QD because of this fiasco, and I may very well end up doing so, but Elite Iron has a QD mount scheme that is quite tempting as it's basically just a thread on --the can itself threads on several coarser threads on the rear of a muzzle brake, which in turn semi-permanently threads onto various barrels, depending on pitch. They have one with a long brake that goes over the barrel a few inches, kinda like the old AAC one, and the rest are regular length brakes. They have thread protectors, and then these thread protectors that are really directional brakes, like the Levang Linear Compensator --they thread over the brake and vent all the gas straight out the front. Simple system, but genius.

He (Mr. Poling at Elite Iron) has my DTA HTI .50BMG barrel right now, fitting it for a new brake and a can. A brake I can remove in the field, timed and using no shims, and a suppressor timed the same way. Provided it all turns out well, I may very well go with him on a QD setup in .30 for use on .300BLK, .308 and 6.5G, and another in 5.56, dedicated for such.
 
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


Hi, I gooogled around to figure out how to solve my M4-2000 rattle problem and found this thread and your post. I used your process except for the sharpie part, my Brakeouts' just needed a little material removed, so I skipped that part. I went slow and checked it until it fit nice and tight. Thanks very much for your how-to!
I looked on Youtube for a video and could not find one, so I made one. If somebody see's something I did wrong and that is going to screw up somebody else trying to "grind down" the edge, let me know and I'll take it down.
I've found this site very helpful.
Thanks

 
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A friend and I decided to fit our mounts with a variation of the dowel method... we had a machinist cut an adapter that is threaded 5/8-24 on one end, and is a bit less than 1/2" on the other end. Thread the adapter into the mount, chuck the whole deal into a drill press; use a steel ruler with some medium and fine grit sandpaper wrapped around it to take material off the bevel. Stop and check often, making sure to keep the release latch depressed when test fitting so as not to wear out the engagement teeth. We were able to fit several adapters over the course of an hour or two, and we're getting good, solid contact on that tapered shoulder (as verified by the Sharpie test fit method). Add a little cold blue to the shoulder when done to take off the shine, and Bob's your uncle.

I haven't yet had a chance to do any accuracy testing with the fitted mounts, but I certainly doubt that any harm was done in that regard.
 
Looks like the definitive home DIY process to date to me (unless you're dealing with blind pinned ones like I am) but Burnout sounds like he's got a good method going too in order to protect the teeth... There's also this lapping tool that looks a lot like a small dental tool but it's abrasive; I think EZ Lap may make it too but I can't be sure. Small handle and angled end with a small tip? Wish I could remember the exact tool because it seems to be made for this task.

You should forward these to AAC and propose that they do this at the factory before shipping them out!

Seriously, thanks, I think your use of the angle is just what I need to fix this one that's so bad it HANGS off the end and eclipses the bore. I was worried anything short of machining this one on a lathe could be disastrous, but this is worth a try. Worse thing I'll just be out the mount, which I am now anyway --can eclipses the bore it's so loose!

I swear though, I bought my last AAC can. Nice cans, best materials, but I'm done doing this shit with their NIB mounts and give-a-fuck CS when they kick out a junk product. Funny, when the 51T FIRST came out, they were Johnny on the spot with FREE replacements if you had a complaint... But that ended FAST when they realized what they'd done.
 
I really hate to say this since I'm sure it's been said before in this long thread but, spending the extra cash on my Surefire can seems to have been well spent money. I have had ZERO problems, thousands of rounds driven through it, and locks up now the same as it did when I got it.
 
OOOOOOOOOOO!!! He said Double Dog Dare!!! That is classic...gotta love it. It has proven no point in the past though. All I'm ever told is "You're just paying for the name Surefire". Well, after long use of my own, testimonials and use of others, YES I did pay for a name....and damn glad I did. I own two AAC pistol silencers, Aviator .22 and Ti-Rant .45. Love the hell out of them...almost bought a Ranger 3 or M4 2000 before heavy research boosted me to get a Surefire. I wanted a can that could be beaten to shit, rode hard to hell, to the top of the hill and back being drug by a bat straight back out of hell. So.......I Googled it....... That's why I got a Surefire.
 
This thread doesn't exist. I was told at ARFCOM (actually way more AAC fanboys there than still exist at Silencertalk) that AAC CANS DO NOT WOBBLE. And only an idiot pays for a "loud" Surefire.

Loving my Socoms. But if you did get stuck with an AAC that wobbles, just do the "fix" and move along. What's funny to me is the number of people who stomp their feet saying it isn't real issue, "their" aac can doesn't wobble ;)
 
I have an m4 2008 bought when the 51 tooth mounts came out. As it was riding on an 11.5 sbr the accuracy was never an issue. The can is very quiet, and I was satisfied until I used it on a Larue Stealth 18 inch upper, and it opened up ten shot groups by .5moa.
I can't be upset, because when I bought it AAC was not marketing the M4-2008 as a precision rifle can; most advertising had it on SBR carbines, and at that it excels. And a 50% spread is not that bad for 5.56 lake city ammo.
The BayouRobert fix is not permanent and if you search his posts he writes that eventually the wobble came back.
Mike Mers told me if you leave the can on long enough carbon deposits will eliminate the wobble, and it works. But if you reattach it you start from square one.
The AAC of today is not the dynamic company of 2008. Freedom Group bought them out in 2009, and founder/head wizard Kevin Brittingham was fired. The remaining corporate culture has been slow to bring new products out or to fix existing problems. Kevin is now at Sig USA.
Surefire sure does make a great product, but you may not know their baffle stack is actually a copy of the OpsInc stack, pirated away from them by their ex-salesman Barry Dueck. The mounting system is of course a great improvement, but is it worth 1k more than an OpsInc (or now Allen Engineering) can? It's your money.
For a precision can today I would go Thunderbeast or Allen Engineering, and with the money I save get more ammo.
 
when I bought it AAC was not marketing the M4-2008 as a precision rifle can
Correct. The larger issue I have is people still recommending AAC 51T cans today, there are just WAY better options (in terms of mounting system).

The AAC of today is not the dynamic company of 2008.
Correct. As much as Mike Mers will get on the internet saying it's the same company, and that somehow they are better now for being under the same roof as Tapco, that old company is now officially dead. That's not to say new AAC won't make something great.

Surefire sure does make a great product, but you may not know their baffle stack is actually a copy of the OpsInc stack, pirated away from them by their ex-salesman Barry Dueck.
LOL. Ok, and the Thunderbeast is an almost direct copy of AAC's fluted cones, size, angle, number and spacing. Just machined Ti vs Stamped steel. I'm not sure what your issue would be with SF doing that but not TB. Gemtech's new monocores look a lot aspects of Silencerco/AACs. Making accusations that a company isn't improving upon and making their own way just because they started with an existing design is lame. Don't do it, and if you do, do it consistently please.

The mounting system is of course a great improvement, but is it worth 1k more than an OpsInc (or now Allen Engineering) can? It's your money.
First off, 1k more, no, just stop. I'm not even going to look up the MSRPs because they don't mean anything. Second, as for the difference in street price, yes, it absolutely is worth it to pay for the better mounting system. I think that's the overall moral of this thread!

As for your can recommendations For a THREAD ON can, today, I don't think the TB wins over to the AAC 300-TM or Titan-Ti, in any way at all. But TB are good cans. OPS/Allen are sort of 90's cans that just refuse to go quietly into the night, no thanks. By your own description, it's like getting a SF without the mount.
 
I base my pricing on the ADCO firearms and Silencershop web pages; an AE30 sells for $675, and the barrel contouring is $120 if done by ADCO. They sell the SF SOCOM7.62 RC for $1619 without the mount; Silencershop sells the SF can with brake for $1654, that's almost 1K more ain't it? But it is undeniable that SF makes good stuff, and if I wanted a copy of the latest Mk18 I would go for heir 5.56 can.

I prefer thread on for bolt action rifles, less variables involved. The AAC 300TM sounds great on paper, like my Cyclone without the weight.
As for Ops Inc / AE cans, I guess I should throw them away then because they are 90's cans. The two 12th models I own should be recycled into roofing nails I guess. Might as well dispose of the KAC NT-4 too, in fact it is an 80's can and no longer works.
Gee whiz while I am at it I should get rid of the Spec Ops Shop Genesis 9mm can for the mp5, manufactured in 1989.

Seriously, all the above as well as the SF cans you mentioned are worth buying. It's all a matter of time (ATF), and money.

But I agree, if I were to buy a can for a precision rifle today, it would not fit on an AAC mount.
 
This thread doesn't exist. I was told at ARFCOM (actually way more AAC fanboys there than still exist at Silencertalk) that AAC CANS DO NOT WOBBLE. And only an idiot pays for a "loud" Surefire.

Loving my Socoms. But if you did get stuck with an AAC that wobbles, just do the "fix" and move along. What's funny to me is the number of people who stomp their feet saying it isn't real issue, "their" aac can doesn't wobble ;)

I can see this, I'm sure a there are people with one or two mounts that work fine, and then there's the ones that haven't had their strike yet and just don't give a damn about accuracy.
 
I can see this, I'm sure a there are people with one or two mounts that work fine, and then there's the ones that haven't had their strike yet and just don't give a damn about accuracy.

Out of four AAC 51t mounts only one locks up solid, the other three wiggle a bit, but not enough to cause a major misalignment as some have reported. Not confidence-inspiring as the bore on the AAC's are usually tight.
 
Out of four AAC 51t mounts only one locks up solid, the other three wiggle a bit, but not enough to cause a major misalignment as some have reported. Not confidence-inspiring as the bore on the AAC's are usually tight.

I have several mounts now and every damn one locks up different. From barely to near-rock solid. The ones that have minor wiggle and are easiest to fix, when fixed, can tighten up the groups considerably.
 
Interesting using the O ring, but I rather polish the mount a little bit to get it to the next lockup tooth. What I would worry about with the O ring is melting point temperature and lockup vs recoil wiggle.

Plus fine sandpaper vs a $40 O ring.. sandpaper is cheaper.
 
Picked up my 762 SDN yesterday, have a little wigglage on the 5.56 flash hider mount, stills lines up with the bore of AR without issue, runs great on noveske switch block upper. Tried on 7.62 brake out mount I installed on rem 700 aac 308, rock solid and lines up with bore.

I can live with that. Also very happy with performance, sounds like a unsuppressed .22, no ear pro needed, I was in Marines for 6 years and dealt with machine guns and aircraft so my hearing is slightly damaged already. My dad was impressed too, he's old tho bad hearing too.
 
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Hey, get the hearing tested! I had same experience as you, firing MG's, no ear pro. No ear damage though... I did damage the cilia (fine hairs) from demo though. I hear ringing but pass hearing tests with flying colors. Go figure. .357 magnum with hot loads in close quarters has deafened me the worst of all weapons I've used, though temporary, it was brutal.

SDN-6 is a FINE sounding can and VERY well made --great materials. Glad to hear you got a couple of mounts that satisfy you, they haven't worked out that way for all of us. I have a couple I can live with too, one I'd afraid to use at all and a couple that have been worked to be as tight as thread-ons with accuracy similar to such.

It's just a buyer beware situation due to their CS mostly. They basically abandoned the design once problems cropped up en masse. Like I said, at first their CS was stellar and I'm sure I have a glowing review for them somewhere on here.

Beware also using 5.56 down these cans. I've heard more than one person say, for whatever reason, they had strikes with 5.56 in these cans despite what appeared to be sufficient clearance. And they can also be problematic with some very short and particular .300BLK barrels, for what it's worth.

When AAC says "axial rotation only" that's a line of BS and I'll call that to their faces. I have proof.
 
You my friend should go play the lottery immediately. I've had the same problems with my SDN-6 and I went the sanding route as well. Also after you shoot a few hundred rounds of Norma 203-B which runs a bit dirty I've found, the gaps begin to fill in with carbon and now the fit is very tight. One thing to note which I don't know if many people are aware of but the teeth on the brakeouts are a pretty soft metal so if you're frequently taking the suppressor on an off they will grind down. The best way to take the suppressor on/off is to hold down the latch, screw it on, then disengage the latch at the bottom.
 
Just tried the "fix". Was able to get my SDN-6 to lock up tight on one of my mounts. Absolutely no movement. All it took was a little work with a fine metal file. I was really surprised at how little I had to remove before the latch advanced to the next notch. We'll see what effect this as on accuracy and if it holds after a little use.
 
I must say that I was thinking I was in for a big headache from reading all the horror stories about these suppressor mounts. I have three mounts and when suppressor came in I tried them and they all lock up tight with no wiggle and I have very little poi shift. I must be extremely lucky. I love mine.
 
My AAC can "wiggles" and I read this thread just before I got it.
I use my 762-sdn6 on my 6.5 creedmoor. The poi shift depends on your velocity.
And concerning accuracy.
NCM_0734.JPG
My advice is just shoot the damn thing
or
"wiggle it,just a little bit"
:p
 
I really appreciate the positive solutions. Sounds like it may not be perfect but that there is a workable outcome. Thanks guys for the suggestions.

Have an M4 -2k pending and will be looking at these fixes to get her tight once received. AAC makes nice shit, they seem to be evolving albeit slowly. Lot of good product out there.
 
Here's what I'm using now...with some pictures included.
020 Kalrez Perfluoroelastomer O-Ring, 4079 Compound, 75A Durometer, Round, Black, 7/8" ID, 1" OD, 1/16" Width (Pack of 1) $40.73 on Amazon
View attachment 30216View attachment 30217View attachment 30218

Don't know how I missed this. I do my best to sh*t all over most any post about AAC cans - esp. the POS SDN7.62-SD - whenever I can.

THIS looks promising. 600 degrees F is 50% higher than Viton (400 degrees F).

Interestingly, AAC uses Viton seals on the Evolution-9 can. I got mine without seals and ordered a bunch from their recommended source.

No one answered the phone or emails for me for this one either.

What DID happen is I sent the 7.62 can back, they gutted it, fitted a new QD mount to the back and internals (there were baffle strikes) and sent it back with a dozen different flash hiders. I've found ONE that works - marginally - I usually get 2-3 rounds on target 1/2 MOA and then POI shifts and it's like a long-range shotgun 2-3 MOA dispersion.

What the hell, in for a penny, in for a pound, $40 won't kill me and it might make this can more useful.

I'm replacing it on a DPMS REPR with a SF Socom 7.62-RC, the AAC SDN-7.62 will go on a DPMS carbine for CQB where 2-3 MOA won't matter.

Thanks.

Norm
 
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So I just stumbled upon this mega necro post because I just tried to zero a mk18 with a sdn-6 sitting on it that has been sitting in the safe a few years (divorce/life). I posted on ar15.com about the issue because a simple 50yd zero, no can, 10 rounds stack nicely in a 1" s quare, the second I put the AAC on, that turns into birdshot in a 2.75"-3" spread. I thought it was maybe the ammunition (55gr M193) but it now is seeming to be a side product of the wiggle, which my can does have. I tighten it all the way and then it backs off that little extra bit. I have recently bought a dead air sandman and am debating spending the $200 or so to have this sdn-6 swapped to keymo. Has anyone done this?
 
Here is a thread about Ecco machine. I am in about to send him my can when he starts accepting work again.

 
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?
I know I’m a little (A LOT) late to this conversation. But I know exactly what you’re talking about. I had the same problem for a whole year when I first got mine. And for most of that year, I didn’t even know it was happening. (Luckily I had no baffle strikes) so the fix is simpler then you’d think. So I got some muscle on me, and I grabbed the Can and twisted with everything I had. It took a couple tries. But it finally clicked to the last tooth. And now when ever I twist it on, I just give it a lil extra Emph! Then BAM! on all the way
 
Send to Ecco and save yourself the hassle

Kinda frustrating to take your brand new can and mount to a dowel and drill with sand paper to make it work.

As mentioned above prior to just getting it corrected.

I sanded down the surface it locks onto to allow it to snap over the next tooth.. eventually the lockup lever snapped on mine.

I put my 556 on with a strap Wrench and was sick of having it solely on one rifle. They had to cut it off with the mount on. As it was in there so tight it unscrewed the muzzle device.
 

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