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Suppressors Using my SDN-6 as a screw on can.

MadKap

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Jul 5, 2010
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Thought I would ask the experts.

Is there something wrong with using my SDN-6 as a screw on can?

So basically locking the can to a 51t mount, and then screwing that onto a barrel?

Why would I do this you might ask?

I live in WA state, so I cannot have an sbr. I'm planning on having a sleeve built for a 300 blk gun.

Something like this:
http://www.tacticalsol.com/tshome/wp-content/uploads/2011/08/sbx1.jpg

Anyways, aside from the ludicrousness of having to do this in the first place, is there anything intrinsically wrong with my plan?

Will my chance of getting a baffle-strike increase somehow? Do I need to worry more about the can coming loose than with standard thread-on cans?

Would love feedback on this idea.
 
Re: Using my SDN-6 as a screw on can.

That should work just fine.
The only problem that I can see is the mount becoming fused to the suppressor if it is not removed periodically.

Are you looking for a look like this?
P1010272_WEB.jpg
 
Re: Using my SDN-6 as a screw on can.

I think so! Is that your set-up? I plan on removing the suppressor from the mount quite often as I use it on my other firearms as well.

Can you tell me a little more about that set-up. What's the inside diameter of the tube housing the supressor. The SDN-6 is 1.5 inch diameter can, but I believe I will need a bit bigger interior diameter tube than that due to the protruding locking mechanism.
 
Re: Using my SDN-6 as a screw on can.

Oh yes, I'd also expect my suppressor to protrude half an inch or so in order to better unscrew it.
 
Re: Using my SDN-6 as a screw on can.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MadKap</div><div class="ubbcode-body">I think so! Is that your set-up? I plan on removing the suppressor from the mount quite often as I use it on my other firearms as well.

Can you tell me a little more about that set-up. What's the inside diameter of the tube housing the suppressor. The SDN-6 is 1.5 inch diameter can, but I believe I will need a bit bigger interior diameter tube than that due to the protruding locking mechanism. </div></div>

Yes, that is my setup.
It is a 300 BLK upper that uses a PRI Rifle Length Tube, 10" Noveske Barrel and a TBAC 30P-1 Suppressor.
(Since I planned on used the PRI Tube, I couldn't help but add the MK12 MOD0 hardware to round out the look.

I remove the suppressor after every range session to minimize condensation.
It also serves double duty on my FN A5-M SPR setup.

The TBAC 30P-1 is also 1.5 inches in diameter.
I had to grind down some oh the excess threads from the rail mounting hardware, but it didn't take much to have plenty of clearance.
I can mic the ID of the tube when I get home if you like.

Cheers,

Phil
 
Re: Using my SDN-6 as a screw on can.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MadKap</div><div class="ubbcode-body">Oh yes, I'd also expect my suppressor to protrude half an inch or so in order to better unscrew it. </div></div>

You are going to want to have more than a 1/2" of suppressor sticking out. Otherwise you are going to have problems getting it tight enough and potentially even removing it.
 
Re: Using my SDN-6 as a screw on can.

You will eventually have issues if you try to remove the 51T adapter from the can...the carbon residue will act like a glue if it builds up too much.

In my experience, I have had direct thread cans start to loosen after a bit, which could cause baffle strikes if you are careful.

You could always move to a better state.
 
Re: Using my SDN-6 as a screw on can.

Dr. Phil (never thought I'd say that), your set-up is still an sbr though then? Or is the rifle tube welded to the receiver and then sufficiently long to be considered a 16" barrel?
 
Re: Using my SDN-6 as a screw on can.

I haven't measured the OAL with the tube.
The lower is Form 1 SBR's anyway, so I didn't care about that.
I'll measure everthing later today and let you know.

Another option for you is Glen Seekins rail systems.
He has designed them to allow access to the QD ratchet release through the rail.
sp_modular_quad_rail.png


sp_bar_quad_rail.png


http://www.seekinsprecision.com/index.ph...3&Itemid=37
 
Re: Using my SDN-6 as a screw on can.

I cant stand the SDN6 mount, or any not so quick, quick ratchet style. If you intend to use it as a screw on can then i don't think its going to hurt anything. We do the same exact thing with ours. Its no slower to just screw it on than it is to screw it on and hear it click... but mine doesnt come loose on it mount either..

Encase you do want to take it off and on as intended our rail systems pictured above make that possible
smile.gif
 
Re: Using my SDN-6 as a screw on can.

Glen,

Those rail systems look amazing. Will they extend far enough to function as a 16" barrel if the rail is perm attached to the barrel nut (or whatever a permanent solution would be).

I'm looking for a solution given I live in Washington state with no access to SBRs.
 
Re: Using my SDN-6 as a screw on can.

why not go with something like the Cyclone? i'm not sure you'd want to attempt locking the 51t mount to the SDN6.
 
Re: Using my SDN-6 as a screw on can.

I'm not planning on locking the mount anymore than using the standard system (not welding). I probably should have gone with a thread on ti-can, but I'm not really interested in buying another can right now as the sdn-6 is 'good enough' in all avenues.
 
Re: Using my SDN-6 as a screw on can.

If you're not going to be messing with the QD system, just go with a thread on can. The new Hunter model from AAC is basically an improved Cyclone K. Another one to wait for is the Saker in 7.62 from Silencerco. It'll have the ability to change between thread on and quick detach as you choose.
 
Re: Using my SDN-6 as a screw on can.

Hey, have you talked to Cascade Arsenal? Chip Miller? He is a dealer here and I bet he knows all the ins and outs and ways around the no-SBR thing. Maybe that will change some day.
 
Re: Using my SDN-6 as a screw on can.

I do! He is actually my dealer. Great guy, I should talk to him.
 
Re: Using my SDN-6 as a screw on can.

Thought I'd check back in on this thread an ask:

Is there any precedent from the ATF allowing a perm-attached rail, maybe a monolithic style upper that goes further than a 16" barrel but having a shorter than 16" barrel below it to be considered 'not an sbr'?
 
Re: Using my SDN-6 as a screw on can.

The current ATF rulings define a barrel pretty specifically, I don't think you're interpretation would stand up right now. Especially since the barrel is removable from the upper receiver. You would have to somehow attach the barrel to the rail or vice versa, to make it compliant. Basically the only way in Washington is to have the can permanently attached. It sucks.

Edit: In case that wasn't clear, in order to count towards your barrel length, whatever you are measuring to must be permanently attached directly to the barrel. So in your example you would have to attach the rail and receiver all in a way that they cannot be taken apart.
 
Re: Using my SDN-6 as a screw on can.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MadKap</div><div class="ubbcode-body">Thought I'd check back in on this thread an ask:

Is there any precedent from the ATF allowing a perm-attached rail, maybe a monolithic style upper that goes further than a 16" barrel but having a shorter than 16" barrel below it to be considered 'not an sbr'? </div></div>

I understand your idea and the thinking behind it, but you're asking for a headache later. Every LEO that see's it will believe even with the way your setting it up that it's an SBR and you'll end up in court and in the long run paying time and money to defend something that's questionable. And if you have to worry about baffle strikes then you might want to ask yourself if it's worth it. You're better off doing a pinned brake that brings your OAL to 16" without the worry later of someone questioning it. If what you wanted was doable I'm sure Rainier Arms or any number of others would already be doing it. Just my .02 and I am definitely no expert...
 
Re: Using my SDN-6 as a screw on can.

Thanks for the info guys, looks like I'll need to talk some of the local smiths and manufacturers to see if there's any history of this set-up here in WA.
 
Re: Using my SDN-6 as a screw on can.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MadKap</div><div class="ubbcode-body">Thought I'd check back in on this thread an ask:

Is there any precedent from the ATF allowing a perm-attached rail, maybe a monolithic style upper that goes further than a 16" barrel but having a shorter than 16" barrel below it to be considered 'not an sbr'? </div></div>

Again, talk to Chip to check all this out, I'm sure he hears it everyday. You could also talk to the guys at Rainier Arms. I bet they get even more questions about it. The guy that does their welding is also a Boeing welder and does phenomenal work --he blind pinned my Brakeout on a 14.5" and you really have to look to see the weld, it is that good. But I do have a couple other things to add now that my memory got jogged.

1. You can write ATF while you are waiting, you'll get your reply back fairly quickly all considered (weeks to a month maybe?). You need to send it to the Technology Branch in GA. Tell them exactly what you want to do, maybe even include a picture or two, and ask them for a document saying what it is or isn't. A quick search turned up folks that are doing this, using the tube as the barrel extension and they aren't monolithic either. I don't really see anything wrong with that as far as the law/cops go, but they live in this wierd fantasy land where up is down and left is right, so who knows? Better to get a letter for that.

Note that many people think that putting a Masterkey under an M4 makes it an SBS. But it doesn't, not according to ATF. I've seen a copy of that letter myself, and sure enough, they consider a Masterkey to be an AOW, still, BECAUSE THE RECEIVER IS DIFFERENT! Never would have thought of that one! It makes too much damn sense, huh? So it doesn't hurt to ask. Another note: the guy that did this still recommends to get your own letter for something that everyone is certain would be an illegal SBS otherwise.

2. I know this is good to go: I've seen folks use the short barrel, the long forend, and then they use another tube blind pinned to the barrel. Say a 5.6" tube to a 10.5"bbl, all under a long rail such that the tube barely comes past the end. This tube gives you the required length directly to the barrel and the suppressor fits inside of it, inside of the tube. I imagine it would work best with a thread on.

I'd really only consider this if you plan on keeping it on that rifle for good, because it really stranges it out when the can isn't on it. On the upside, perhaps you could find a double use as a golfball launcher! You also won't be able to reach the gas assy. if need be, but I guess you could cut it out when the barrel is shot out. Just make sure you get a FF tube that will come off over that other tube.

The other option is welding the suppressor on, but that isn't a good idea for a lot of reasons.

Oh, this can is MADE for the .300BLK! You'll like that. I actually have a 16" AAC upper that I got for a killer deal and I put it together with the can and an LMT Defender lower and they sang sweet music together with subs. If that wasn't hearing safe, it was close to it, and most certainly was for bystanders. With 5.56 M855, it sounds a lot like a .22 but a good bit louder. Haven't tried the 7.62 or 6.5 yet, but I reckon they'll be about the same but with a lower tone in 7.62.

And the wife? She was all smiles... I think she got a bigger kick out shooting them suppressed than I did! That is always a good thing. When she started nailing the 10 or 12" plate at 200m with no misses, she was hooked.
 
This is semi-related to a problem I'm trying to solve, so I thought I'd ressurrect this old thread.

I have an SDN-6 that got primarily for a 300BLK SBR. Now that I have it, I'd like some way to have it do double duty on my bolt gun (.308 Rem 700P) without fiddling with the rifle any more than is absolutely necessary. The OPs original question seems like it might be a solution for me, as all I would need would be to thread my barrel. This is of course providing that his suggestion of simply leaving the muzzle device attached to the suppressor and using it as direct-thread is (a) safe and (b) functional, which is I guess what I'm asking.

MadKap - did you wind up trying this? Sent you a PM also.

If this is a no-go, I guess my other option is to cut down my barrel (to 23", which seems like it would be a good compromise to keep my 1000yd reach and still stay under 30" with the suppressor), thread it, and install the mount normally. I'm just not excited about whatever POI change will result from those changes and reworking all my dope. <*Wow, that makes me sound really lazy! I guess maybe that's what it boils down to...*

Any thoughts from the experts are appreciated.
 
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Your best option is to buy a second mount and install it normally, but I have left a TOMB mount screwed into my SAS Arbiter and used it like a direct-thread for a short period. It was hard to get back out after some shooting, required putting the can in a soft-jaw vice and a pipe wrench on the mount to get it back out. I think it would work just fine for the OP's use, something like the following picture, but I'd just put another mount on your second barrel.

sbx-complete-rifle.jpg
 
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This is semi-related to a problem I'm trying to solve, so I thought I'd ressurrect this old thread.

I have an SDN-6 that got primarily for a 300BLK SBR. Now that I have it, I'd like some way to have it do double duty on my bolt gun (.308 Rem 700P) without fiddling with the rifle any more than is absolutely necessary. The OPs original question seems like it might be a solution for me, as all I would need would be to thread my barrel. This is of course providing that his suggestion of simply leaving the muzzle device attached to the suppressor and using it as direct-thread is (a) safe and (b) functional, which is I guess what I'm asking.

MadKap - did you wind up trying this? Sent you a PM also.

If this is a no-go, I guess my other option is to cut down my barrel (to 23", which seems like it would be a good compromise to keep my 1000yd reach and still stay under 30" with the suppressor), thread it, and install the mount normally. I'm just not excited about whatever POI change will result from those changes and reworking all my dope. <*Wow, that makes me sound really lazy! I guess maybe that's what it boils down to...*

Any thoughts from the experts are appreciated.

In your situation I'm not seeing why this would be any advantage over just buying the correct mount and using it. Your barrel is still gonna have to be threaded, your POI is gonna change with the can on either way. I would do that and start saving for a precision screw on can for the bolt gun.
 
I reckon I was thinking that having only the threading done would allow my POI to stay the same unsuppressed, opposed to having to do new dope for both suppressed AND unsuppressed shooting.

The more I think about this, the more I realize it's silly to try and straddle the fence. As you gentlemen have implied, the smart option is to just suck it up and mount the thing. And since I'm realistic enough to acknowledge that once I do the amount of shooting I do unsuppressed will likely be pretty minimal, I guess my point of redoing the unsuppressed dope is mostly moot.

This is probably a question for a seperate thread, but now that I've come to my senses what are everyone's opinions on my mounting options? I've read all I can find on the search, but I'm still trying to evaluate pros/cons of the AAC Blackout, Brakeout, and plain 51T Brake that are the mounting options for my SDN-6. I'm reluctant to go for the straight brake as I don't want my buddies to find shooting with me unpleasant, but I'm also concerned that the Brakeout compromise may be the worst of both worlds rather than the best of both. Anyone have experience comparing these? There's lots of info out there on AR usage, but I've had less luck finding comparisons with long gun use.
 
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When I read through this thread I was left with two major themes that are appearing more and more....

1. Folks that live in a NO SBR State seem to want to own....SBRs.
2. Understanding the POI shift from "can on/can off" and same can, two different rifles is rarely anything other than "you are hosed." Really accurate cans by themselves are hard to come across.

The real estate that makes up the front part of any suppressor is some of the most precious real estate there is for suppression performance values. In other words, the first couple of chambers pretty much sets the standard for overall suppression. When you give that up with QD, you give up a great deal.
That thing...that metal thing...that flash suppression and/or brake thing that you stick in your suppressor and might make up a good 25%-30% of your can's entry is nothing short of useless for both suppression and accuracy retention. What it is good for? Flash hiding and breaking when it is all by itself in the open environment. And some of current in production designs are far from as effective for that as their stand alone non-QD designs. Some will say that QD keeps cans on better than thread on, but that depends allot on machining tolerances, designs and IQ. Whatever you believe, the truth of it is when you stuff QDs in a suppressor, those QD mounts no longer provide flash suppression nor breaking. What they do do is either just get "cut-off" by the can and become free bore space...useless....or in some instances create back pressure and/or hot spots and/or crap traps.



Why mention all this? Without QD a can becomes a great deal shorter and some would argue more quiet and more accurate as well. If one is trying to build a make pretend SBR and is willing to give up all resale value, well why not add a thread-on on a 16" barrel and be done with it.
A 10.5" / 14" Barrel is harder to suppress well to begin with.

Nothing wrong with a little POI shift as long as it remains constant.
 
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