Suppressors AAC 762-SDN6 POI Shift Issues

[linsmea]

I have an AAC 762-SDN-6 that I bought around 2012 and mostly used it with 5.56 and a little 7.62. I recently got into shooting precision .308 and noticed the POI shift is really bad - what makes it worse is that it seems inconsistent, so it's hard to even compensate for. At 100 yards, it impacts about 1-2 inches right and 2-6 inches low. I'm using a Bergara HMR with 175 SMK and can reasonably stack groups sub-MOA without the can. There are no baffle strikes that I can see. The mount is on straight. I'm more or less at a loss though of exactly why this can shoots so terribly. Any input or advice would be appreciated.

 

[smokin.338]

Could be as simple as barrel harmonics or could be a baffle strike with shifts that great. How is it your muzzle device mounted and what kind is it ?? Shine a flash light from both sides of the suppressor and rotate slowly to check for strikes...

 

[JSTARSZ]

Advice you are not going to like - I have four suppressors, AAC, Gemtech, and 2 Thunderbeasts and by far the most inconsistent is the AAC M4/2000. I tried it on a precision 223 bolt rifle and just became frustrated with it and finally bought Thunderbeasts and have been happy ever since. The AAC now only gets out with the AR's, where precision is not the name of the game. I don't have a SDN-6 but have read they are hit and miss as far as consistency goes. Since you are married to these circular items forever I now only buy what I know works - Thunderbeast. There are others that work well too but I will stick with what I know works. It leads to less frustration.

 

[linsmea]

Advice you are not going to like - I have four suppressors, AAC, Gemtech, and 2 Thunderbeasts and by far the most inconsistent is the AAC M4/2000. I tried it on a precision 223 bolt rifle and just became frustrated with it and finally bought Thunderbeasts and have been happy ever since. The AAC now only gets out with the AR's, where precision is not the name of the game. I don't have a SDN-6 but have read they are hit and miss as far as consistency goes. Since you are married to these circular items forever I now only buy what I know works - Thunderbeast. There are others that work well too but I will stick with what I know works. It leads to less frustration.

Thanks, I was actually thinking that it might just be the can itself. If I knew then what I know now, I would have definitely gone with a Thunderbeast and bought a different can for my 556 rifles. I haven't done anything since 41F so maybe I'll look into it.

 

[186thFCo]

Do you have the QD version with the 51 tooth flash hider or break? I have an 7.62-SDN6 QD, but i would never put it on a precision rifle hoping that it will be accurate. My SDN6 will always have a slight wiggle in it and even if I get a strap wrench an tighten it as much as I could, it would always come loose just a bit with recoil, to where the wiggle will come back and through off rounds even at 100 yards. I have heard of people here that installed a set screw to prevent it from coming loose but I wont do that. I use mine mainly on an AR-15 chambered in 300 BO and i love it for that, makes my AR quieter than a cork gun if i use sub sonic rounds. If you want a suppressor for precision than get either a direct threaded version or go with a set up like SAS Arbiter with a T.O.M.B. or similar.

 

[craigos]

Not sure what the issue is, you stick a can on a barrel - no matter the can - the POI changes relative to a bare barrel. I own 20+ suppressors - everyone of them has POI shift - relative to a bare barrel. What you want is POI min shift shot to shot when you remove and re-attached.

So my question is

- take a shot with the can on
- remove the can, add it back on
- take a shot
- same place - if yes ----- its working as designed.

 

[linsmea]

Not sure what the issue is, you stick a can on a barrel - no matter the can - the POI changes relative to a bare barrel. I own 20+ suppressors - everyone of them has POI shift - relative to a bare barrel. What you want is POI min shift shot to shot when you remove and re-attached.

So my question is

- take a shot with the can on
- remove the can, add it back on
- take a shot
- same place - if yes ----- its working as designed.

That is the issue, the POI shift with the can is not repeatable, groups open up quite a bit and even a bit random at times.

 

[Strykervet]

SDN6 was my very first can and despite knowing the problem with them fully well, I got more anyway. I have several cans and own 4 AAC's, all 51T's including 2 SDN6's and 2 5.56SD's. The problem is inherent in the mount's design.

Easiest fix/best fix: replace with a Sico Saker or TBAC Ultra. Saker, that's saying you are looking for a can with similar attributes as the SDN6 such as avg. size, QD mount and capable of abuse. If abuse isn't a factor and QD doesn't have to be of a non-thread type, TBAC Ultra is hard to beat. The 9" is awesome for sheer performance on a bolt gun or semi that's not abused (TBAC cans don't like mag dump after mag dump; use your SDN6 for that). Elite Iron is another to consider, similar to TBAC in a lot of ways but uses SS and costs less due that one attribute. Their cans are tanks but they are heavy; awesome for .50BMG and .338LM though. They're all great cans and I could go on about the attributes of each, but I will say Saker can use several different mounts with the right part and also has removable end caps, each with different attributes.

Surefire is said to make a good can, but I hear conflicting stuff about them, so I don't know; I almost bought one when I got my SR25/M110, but opted to go with the new KAC can, the full length QDC? KAC same, though I do own one of their newer ones I've been waiting 14mos... By the time I get it, it'll be obsolete! ATF says any day... Glad I got most prior to 41F. Anyway, KAC mount looks solid, that's all I can say. There's no ratchet teeth or threads or anything that can be damaged in the field.

Least expensive fix/May work, may not: replace mount or fit the mount you have via removing material from the beveled face the can adjoins OR weld the mount to the can and use it as a direct thread. I recommend staying away from their flash hider, period. Use the brake or Brakeout (2.0, etc.). They don't PING! like a tuning fork; if you don't know what I'm talking about, then you don't own the flash hider and trust me, you don't want to. Actually works great on flash though, just too damn noisy!

Ultimately it's best to use these AAC cans on "rack grade" rifles, like issue M4's or a more basic SBR setup. Like more than a few AAC owners on here alone, it's what I've basically done with mine; I actually bought the 2 5.56 cans cheap for just that purpose knowing their inherent flaws. Because what you are experiencing is the wobble of the can on the mount. It's far more noticeable the worse the wobble and the more accurate the rifle, and a thin barrel can exacerbate this as well . In general, they shift the POI one way or another but also open the group up proportional to the wobble or error in the mount. The worst wobblers can be all over and begging for a strike. My FAL had a mount so bad it eclipsed the bore and I was afraid to use it. Years later, AAC FINALLY sent me a replacement --week after Remington bought them no less. AAC is also famous for horrible CS and knowing the mount is bad, attempt(ed) to pass blame onto the customer so they'd have to foot the bill. Expect a ~2MOA shift, if not more and +2MOA or more for the group to open up, and I'd say that's to be expected with an AAC QD can. It's also why I say it has decent use on rack grade rifles because the worse the rifle to begin with, the less noticeable the slop these cans create. In my safe, a rifle with no FF tube and with chrome lined barrel earns you an AAC can! It is hit or miss though, as I have some rifles with fitted mounts and they actually fit tight, solid and have acceptable groups. The more mounts and cans you have, the more likely to find a winning combo, downside to that is you have to have more mounts and cans --best buy better cans in that case.

With most of my other cans, which are TBAC, Sico and Elite, the shift is repeatable and minimal. In general, the POI is almost always low by 1-2MOA, depending, usually dead at 6 o'clock but some aren't. As it should be for a $1k barrel attachment IMO though. With Elite, you can no-shit tailor the POI if you like. They index thread on cans to the barrel so the baffles are TDC; because you don't have to send in the barrel or indexing nut they send you, I suspect their cans are automatically TDC to the mount, which in turn will be aligned to the barrel. Not something you HAVE to do, but nice to know my POI is gonna be in a certain place each time. Elite is also likely peerless when it comes to custom work and Dale has done some awesome stuff in the past, including cutting me a custom brake for the DTA HTI .50 that's precision aligned for the barrel so I need no washer to line it up when I swap between that and the can. TBAC made me right when they sold me the older 30CB9 and came out two weeks later with the Ultra 9; I wasn't pissed but a little bit sore. Zak made it right and I own more Ultras now and plan on recoring that CB9. Sico is just a quantum leap ahead of much of the competition with newer designs that WORK. Omega 9k is a perfect example of this --I don't know if it's a great short 9mm can or a great short .300BLK can. Maybe both. Saker is peerless in it's class, and if you, say, dreamed about what a "perfect" SDN6 would be, the Saker is that can.

Sorry, wish I had better news or information to give you.

FWIW, the SDN6 itself is a very well made can, and comparing AAC direct thread cans to Sico direct thread cans comes down to whether you think Inconel is overkill enough or if you want Stellite instead. In other words, the AAC can is solid and on par with other industry standards. It's the mount that killed the cans, the customers and ultimately, the company's old staff. I'd like to see AAC change their lineup in the future after stockpiling enough parts to service what's out there indefinitely. If not, they've seen the last of my business.

Good luck!

 

[Mopseydocks6014]

This is the first I've heard of it. Kind of unhappy. I have a SDN6 that I use on my MK18. Works great on that, but I don't shoot more than 100 yards with that. I'm having a 6.5 Creedmoor bolt gun built this winter and the plan was to use it on that. Now I'll have to invest in a direct thread can. I guess Thunderbeast will be the best bet.

 

[HansohnBrothers]

This is the first I've heard of it. Kind of unhappy. I have a SDN6 that I use on my MK18. Works great on that, but I don't shoot more than 100 yards with that. I'm having a 6.5 Creedmoor bolt gun built this winter and the plan was to use it on that. Now I'll have to invest in a direct thread can. I guess Thunderbeast will be the best bet.

AAC has said the SD-N6 wasn't intended as a precision silencer, more of a CQB/hard use model. For long range precision shooting, the Thunder Beast Ultra series is currently the best option, IMHO. Avoid direct thread, go with the taper mount.

 

[BurnOut]

One thing you can try is fitting the 51T mount to the can by machining or sanding down the beveled edge of the mount onto which the can seats. On the mount, right behind the coarse threads that engage the can, is a small beveled surface; this is what the body of the can butts up to when it is installed. Moving the face of that bevel back until the ratchet mechanism on the can just baaaarely clicks over to the next tooth on the mount will do wonders for getting a consistent installation of the can (which should in turn provide you with a more consistent POI shift).

I have since sold my SDN-6 and all the mounts, but the way I did it was that I had a mandrel made onto which I could thread the mount, and chucked it in a drill press. Test fit the can to the mount to see how far you have to move the beveled surface, and get the drill press spinning. Use 600 grit sandpaper on a block to dress the beveled surface on the mount, and re-check your fit to the can often. I never really shot for groups with that can after I did that, but we did it with a buddy's SDN-6 as well... and he gets consistent POI shift and easy sub-MOA (average is probably around .6 or so) grouping out of a home-built gas gun in 6.5 CM with the can installed.

 

[linsmea]

thanks for all the solid input. I'll probably try the method BurnOut suggested.

 

[wareagle700]

OP,

Have you tried swapping out the AAC mount/brake for a different one? Maybe its that specific combo that just doesn't want to work well together. I've got no first hand experience with their cans but have heard of AAC mounts and cans causing accuracy issues from more than a few people.

 

[NFALawyers]

My SDN-6 wobbles slightly on the mount. The wobble makes my sub 1/2" gun into a 2" gun. None of my other suppressors do this. I agree with several posters above that TBAC is the way to go for precision rifle. It's what I now use.

 

[Strykervet]

AAC has said the SD-N6 wasn't intended as a precision silencer, more of a CQB/hard use model. For long range precision shooting, the Thunder Beast Ultra series is currently the best option, IMHO. Avoid direct thread, go with the taper mount.

This is the best advice and it's what I did. The TBAC mounts don't have the same problem (NO mount has the same problem except maybe for other AAC mounts). TBAC mounts aren't much different from direct thread IMO, just allow use on multiple rifles. The 6.5 specific can is really nice too, but the .30 got the job done for years until I got one.

 

[Saf3sh00t3r]

I have an AAC 762-SDN-6 that I bought around 2012 and mostly used it with 5.56 and a little 7.62. I recently got into shooting precision .308 and noticed the POI shift is really bad - what makes it worse is that it seems inconsistent, so it's hard to even compensate for. At 100 yards, it impacts about 1-2 inches right and 2-6 inches low. I'm using a Bergara HMR with 175 SMK and can reasonably stack groups sub-MOA without the can. There are no baffle strikes that I can see. The mount is on straight. I'm more or less at a loss though of exactly why this can shoots so terribly. Any input or advice would be appreciated.

I had the same issue and got it to go away and now it's GREAT!!!

Used a high-temp o-Ring on the shoulder of the large thread and the shoulder for the mount. Hard to explain, but PM and I will send you a couple.

I got a box of 30 from Amazon.

This is the infamous wobble with the AAC cans.

Just make sure that once you start tightening it doesn't bind the o-ring. Do it slow once it seats.

No need to Machine a gosh darn thing!!!

 

[flatland1]

I got lucky and met a Class III SOT who had a SCAR 17, and was wanting the correct can for it. I traded him my AAC SCAR-H for a new SF SOCOM 762. My other cans are all TBACs - Ultra 7, re-cored 30BA, 30CB9 - so the SOCOM doesn't see much use. But it's still been head & shoulders better than that SCAR-H was....have never missed it, not even a little bit.

 

[Saf3sh00t3r]

What ever happened? Did the o-rings I sent work out?

I'm just curious.

 

[Strykervet]

The sanding of the bevel is the best bet, some sort of machine to lock it into in order to make sure tolerances are low is better. But O rings have all kinds of problems I can forsee, if it's just range play it may be fine. I don't know. I like my stuff to lock on right, and what many may not know is that the AAC mounts are actually thread ons! The ratchet is just there to prevent it from coming undone due to the large threads. Some axial rotation was intended, but wobble most certainly isn't. Yesterday I shot one I HAND SANDED using machinists blue to make sure I left no high spots, and after a lot of tedious work, I wound up with a rock solid AAC mount with no high points. It was far too much time and work to bother doing them all that way, and once a mount has been modded to fit a can, it'll only fit THAT can, which is a testament to AAC's lack of tolerance control.

These goddamn mounts.... Everytime I take out the SDN6, it always performs AWESOME. It's a great can! It's one of the best for the .300BLK for some reason, even quieter than some of the nicer and longer cans I have! Too bad the mounts are just SHIT. A direct thread AAC would probably be pretty nice, I don't know, if the cans is built like the SDN6 I'd assume it to be. But I'm willing to give them credit where due. I wish I had other cans that performed as well, and some are nice and cost more than SDN6!

But their mount and CS has prevented me from doing future business with them. No reason to put myself through their bullshit when Sico sells what they sell.

And take it from me, I own a bunch of cans including 2 5.56SD's and 2 SDN6's, all 51T, all with the same problem to one degree or another. No other mfg. has this kind of problem with their mounts. Some are better than others, but none suck as bad as AAC mounts.

The best all around can I have is probably the KAC QDC. Costly, but goddamn it's a solid lockup and it's easy on, easy off. Saker is another, hard to say which is truly the better can. TBAC is best for a light, quiet and accurate can, and the thread over mounts they use are as good if not better than direct thread. These three are my favorite cans, not in any specific order though I tend to use TBAC for accuracy and Saker for hard use with the KAC can being a good compromise between the two.

Good luck!

 

[j-huskey]

One thing you can try is fitting the 51T mount to the can by machining or sanding down the beveled edge of the mount onto which the can seats. On the mount, right behind the coarse threads that engage the can, is a small beveled surface; this is what the body of the can butts up to when it is installed. Moving the face of that bevel back until the ratchet mechanism on the can just baaaarely clicks over to the next tooth on the mount will do wonders for getting a consistent installation of the can (which should in turn provide you with a more consistent POI shift).

I have since sold my SDN-6 and all the mounts, but the way I did it was that I had a mandrel made onto which I could thread the mount, and chucked it in a drill press. Test fit the can to the mount to see how far you have to move the beveled surface, and get the drill press spinning. Use 600 grit sandpaper on a block to dress the beveled surface on the mount, and re-check your fit to the can often. I never really shot for groups with that can after I did that, but we did it with a buddy's SDN-6 as well... and he gets consistent POI shift and easy sub-MOA (average is probably around .6 or so) grouping out of a home-built gas gun in 6.5 CM with the can installed.

A long time ago, on an earlier snipershide post, this was discussed at length. There were machinist pictured posted on a do it yourself fix. too bad this post is lost to us, fuck you scout snipershide.
This is a known issue with several series of mounts for the sdn6. Some early mounts work perfect. Then there are the nightmare mounts. Then there are the you just got lucky series of mounts. pray for luck...
Modification as described above (quoted post) was the only way to get consistent performance and consistent point of impact shifts, can on/can off.
Every single mount either my friends or I purchased that didn't come with the can when bought new had to be modified.

We built a line mount (threaded stock-zero runout) to put the 51t mount on, to check for in line threads and can run out, internal and external.
We would have to do the above listed (quoted post) steps to assure tight can fit to the mount b4 doing run out tests. If neccessary, you could chase the 51t threads to get it as straight as possible. Once the externals were checked and modified as neccessary, we went to internals.

We then line bored the inside of the 51t all the way back to the threads, leaving no shoulder inside the 51t, opening up the bore hole to 1/2" true to the threads and mount. (308 mount) 3/8" or so on the 223 mounts.

Then we checked the thread length on the barrel to remove any possibility of muzzle crush or muzzle touch, a real issue on the pos mounts. Once we did all that and could lock the mount against the barrel shoulder, we had a working system that is consistent UNTIL you use it enough to cause wear and the looseness begins to return.

Then you are back to remodding or as in another post, hello rubber viton washer.

This worked for us.

Several people did the above then welded the corrected mount into the can and used it for a direct thread. This was consistency AS BEST YOU WILL GET with this can.

If you want precision sniper grade accuracy, DO NOT BUY AN AAC sdn6.....
If you want a working, full auto, beat it to hell ar can that will be here 10 years from now and don't mind first creating a working 51t mount, the sdn6 is your can.
I'm ok with mine on the blackout, a 6mm-223 40 degree Ackley mod, and a couple of ar15's. It's a working can but not a sniper can. Works on pigs very well.

Several of the other listed cans mentioned here are sniper accurate or competition grade, but you CAN get a lemon in any of them.... but you are guaranteed a lemon with the 51t mount over 50% of the time.
It is what it is....

Hope this was educational.

 

[Idaho Corsair]

A long time ago, on an earlier snipershide post, this was discussed at length. There were machinist pictured posted on a do it yourself fix. too bad this post is lost to us, fuck you scout snipershide.
This is a known issue with several series of mounts for the sdn6. Some early mounts work perfect. Then there are the nightmare mounts. Then there are the you just got lucky series of mounts. pray for luck...
Modification as described above (quoted post) was the only way to get consistent performance and consistent point of impact shifts, can on/can off.
Every single mount either my friends or I purchased that didn't come with the can when bought new had to be modified.

We built a line mount (threaded stock-zero runout) to put the 51t mount on, to check for in line threads and can run out, internal and external.
We would have to do the above listed (quoted post) steps to assure tight can fit to the mount b4 doing run out tests. If neccessary, you could chase the 51t threads to get it as straight as possible. Once the externals were checked and modified as neccessary, we went to internals.

We then line bored the inside of the 51t all the way back to the threads, leaving no shoulder inside the 51t, opening up the bore hole to 1/2" true to the threads and mount. (308 mount) 3/8" or so on the 223 mounts.

Then we checked the thread length on the barrel to remove any possibility of muzzle crush or muzzle touch, a real issue on the pos mounts. Once we did all that and could lock the mount against the barrel shoulder, we had a working system that is consistent UNTIL you use it enough to cause wear and the looseness begins to return.

Then you are back to remodding or as in another post, hello rubber viton washer.

This worked for us.

Several people did the above then welded the corrected mount into the can and used it for a direct thread. This was consistency AS BEST YOU WILL GET with this can.

If you want precision sniper grade accuracy, DO NOT BUY AN AAC sdn6.....
If you want a working, full auto, beat it to hell ar can that will be here 10 years from now and don't mind first creating a working 51t mount, the sdn6 is your can.
I'm ok with mine on the blackout, a 6mm-223 40 degree Ackley mod, and a couple of ar15's. It's a working can but not a sniper can. Works on pigs very well.

Several of the other listed cans mentioned here are sniper accurate or competition grade, but you CAN get a lemon in any of them.... but you are guaranteed a lemon with the 51t mount over 50% of the time.
It is what it is....

Hope this was educational.

So am I understanding correctly that the mount AND the can itself are the problem(s)?
I have an SDN6 and have an SR25 APC on order. Wouldn't want to frustrate myself to death if the can will be an issue. Seems like an excuse to order a Surefire or KAC can? What can would you suggest?

 

[j-huskey]

Both mount and can may be problematic. you could get lucky and have a good one, but nobody so far on here has been really lucky. I do know a few people who built hunting rifles and use the sdn6 with reasonably good results. But it's not sniper or competition accuracy.
The above recommended accuracy cans have very good reputations. look hard at them.
I personally began with a direct thread "jet" can and it worked sniper accurate from day 1 and still does today, 15 years later, HOWEVER, the point of impact shift was greater than I liked and I was uncomfortable with it as a working police sniper system (bolt rifle, heavy barrel, custom built).
12 or so years back, I went to a surefire qd can on my work rifle (GA Precision built AR10, Schneider barrel). It has no point of impact shift. I am sold on it. I have a couple and they work correctly every time. That's my personal experience.
I have co workers and friends with later model surefire cans who have had the same excellent results.
Cons: they are very expensive.
I bought the sdn6 and tried it primarily for the 300bo and after the mount fix, I have no problems with it. It has been fine on my kreiger barrelled spr 223's holding sub moa groups but it does have some vertical poi shift can on to can off. I'm ok with it for those rifles too. BUT, I never got around to putting it on a precision 308. I don't know what mine will do on a quality 308 rifle. it might be fine. I need to find out.
I also have a silencerco qd specwar 762. It's on a pencil barrel ar10. accuracy is competition grade. Point of impact shift on the pencil barrel is extreme. As with the sdn6, I have yet to try it on a precision rifle, can't tell you what it might do. My specwar 556 has no poi shift on the system it's mounted on.
So, hopefully the 762 will show the same on a precision rifle.
I have experience with a few kacs. I worked with a unit deploying to Iraq. 50% of the kac cans sucked. 25% were ok, and 25% were great. The problem was bad enough, it got written up in Army Times. Kac took steps to correct the problems and most kac cans are pretty good, but a few of the suck cans still show up. They cost too much for me and don't perform as well as the surefires I have, no kac for me.
Repeating what I said earlier, read the recommendations above and look hard at them. The recommended cans listed above our posts have solid reputations and excellent customer service. I just don't own any of them because my surefires have met all my expectations and I carried them to work every day, knowing they were the best available when I bought them.
That's my personal experiences, hope it gives you some options.

 

[338LM_Sniper]

Here is a great video link and it works awesome. I have done 3 AAC 51T brakes and everyone of them lock up Super Tight now with my SDN6

https://www.youtube.com/watch?v=uBOloV9gRIc

 

[linsmea]

What ever happened? Did the o-rings I sent work out?

I'm just curious.

I got really frustrated with the can on a range trip a day or two before the washers arrived (6" vertical 5 shot group at 100 yards) and just bought a TBAC ultra-9 (which will probably be in jail for another 6 months). but that obviously doesn't solve my problem with the sdn-6. I have the washers in my range bag so I'll give them a shot next trip. I really appreciate you sending those along. I'll update with their performance.

 

[Strykervet]

One thing you can try is fitting the 51T mount to the can by machining or sanding down the beveled edge of the mount onto which the can seats. On the mount, right behind the coarse threads that engage the can, is a small beveled surface; this is what the body of the can butts up to when it is installed. Moving the face of that bevel back until the ratchet mechanism on the can just baaaarely clicks over to the next tooth on the mount will do wonders for getting a consistent installation of the can (which should in turn provide you with a more consistent POI shift).

I have since sold my SDN-6 and all the mounts, but the way I did it was that I had a mandrel made onto which I could thread the mount, and chucked it in a drill press. Test fit the can to the mount to see how far you have to move the beveled surface, and get the drill press spinning. Use 600 grit sandpaper on a block to dress the beveled surface on the mount, and re-check your fit to the can often. I never really shot for groups with that can after I did that, but we did it with a buddy's SDN-6 as well... and he gets consistent POI shift and easy sub-MOA (average is probably around .6 or so) grouping out of a home-built gas gun in 6.5 CM with the can installed.

You really ought to consider this. Fuck messing with washers, why have a QD can then? If you're gonna fuck with that, you may as well weld a mount in there and call it done.

I have 4 of these fucking things like I said, 2 SDN6, 2 556SD. Same cans basically, same mounts, same problems. Having the impact shift left or right really sucks and the only way I've seen to eliminate that if the can doesn't do it out of the box is to go with an indexed can. Elite Iron does this and KAC QDC cans are VERY nice actually and index too. QDC is quickly becoming my favorite QD can, it has attributes that make it better than the Saker but I think Saker is probably quieter.

IF you work the bevel on these things, they will lock up tight and they won't wiggle. At all. This will improve accuracy, not impinge it. All of mine do this, and it sucks to have to buy a can and mount that price and have to fuck with it, but let me tell you, SDN6 is actually a DAMN NICE can, the mount just sucks but can be unfucked with a little work. Note the mounts are Inconel and a motherfucker to work by hand --I just bought a brake and it was off by what looked like an insignificant amount (sometimes just tightening a can on and off will cause it to slip to the next notch making it lockup solid thereafter --this happened with a brake I just bought, lucked out). 7 hours later I was done polishing the first brakeout by hand. If it's off a lot, send the mount back and get another. If you can, buy several mounts at once, one should lock up by itself and you won't have to do anything. There is no reason there should be wiggle on that mount, but some was considered to be within tolerance at the time they were designed. They claimed it was axial rotation only, but it's not. You know that based on your groups FFS!

These cans were designed to be QD at a time when QD was considered to be a trade off. The military only requires 4MOA for an M4 and M855 combination. These cans were originally designed for the military and so accuracy just wasn't at the top of the list, as usual. They never bothered to unfuck the mounts like the rest of the industry. Again, if you want the best QD can available, I'd have to say KAC QDC. The vertical POI at exactly .5mils was uncanny. I mean, it's dead eye dick vertical, zero windage adj. for sub-MOA groups.

The Ultra 9 is a GREAT can, far better a can than most and probably the best titanium cans made. But I feel it would behoove you to unfuck your SDN6, at least get one or two good mounts so you can use it. It is a good can --when they lock up. And you're POI will at least be consistent. They are AMAZING cans for .300BLK, they really do work well with that round.

Anyway, this comes from years of experience, research trying to find solutions myself and eventually settling on one that worked.

Could be me, could be just this one mount, but the new production brakes seem perhaps have a tad tighter tolerance FWIW. Funny, their cans are actually quite nice, their brakes work really well, their flash hider is one of the most efficient but the fucking mount portion just shits the bed and generally ruins the system out of the box. Go figure.

Good luck, lots of people have done the resurface job on that bevel and you don't see them searching for answers anymore. That's telling. They also don't buy new ones (except me but for the prices I paid it was worth it) so that's telling too.

Dropping the mike on this one.

 

[maddazzshooter]

I have an AAC 762-SDN-6 that I bought around 2012 and mostly used it with 5.56 and a little 7.62. I recently got into shooting precision .308 and noticed the POI shift is really bad - what makes it worse is that it seems inconsistent, so it's hard to even compensate for. At 100 yards, it impacts about 1-2 inches right and 2-6 inches low. I'm using a Bergara HMR with 175 SMK and can reasonably stack groups sub-MOA without the can. There are no baffle strikes that I can see. The mount is on straight. I'm more or less at a loss though of exactly why this can shoots so terribly. Any input or advice would be appreciated.

I own two SD-N6s and I shoot 5in1 groups on regular basis with my Rem AAC 700 . One load is 175 SMKs and the other Berger 185 juggernauts. Those cans are consecutive numbered and only one of them has a .1r-.1d mil shift and the other hold zero.