Finally got a can to fit, can't get much closer... [Archive]

Cameron

06-18-12, 21:22

I have been trying to figure out how to mount a can as close as possible to the 10" rail on a 10.5" SBR I think I got it.

10.5" LMT barrel, 10" Daniel Defense Lite rail and Gemtech M4-02

http://farm8.staticflickr.com/7230/7398542930_d29a5d9b2e_b.jpg

http://farm8.staticflickr.com/7239/7398541230_9c60e9eaf2_b.jpg

http://farm9.staticflickr.com/8168/7398541742_246f3fa76a_b.jpg

Hop

06-18-12, 21:33

Wow, that's pretty tight & looks nice! I'm still trying to figure out what route to go with mine as it's a real DD MK18 with the 10.3" barrel. I doubt your can would work without a shim. I'd rather get a 308 can as well.

Cameron

06-18-12, 21:44

I installed this with a crush washer. I'm pretty happy it worked out.

Cameron

NoveskeFan

06-18-12, 22:31

Is it just hand tight with the crush washer, or did you have to torque it down somehow? Looks great, by the way.

I installed this with a crush washer. I'm pretty happy it worked out.

Cameron

saddlerocker

06-18-12, 22:31

Did you have to shave the Rail? Or did just the crush washer do it?

Im considering having ADCO cut down a BCM 11.5" with 10" Larue rail to 11", to get a more seamless look with suppressor.

It'll still be cheaper than BCM 11.5" with URX II (which BCM feels the need to charge $270 more than uppers with similarly priced rails like the larue)

Iraqgunz

06-18-12, 22:50

Are you concerened about the rail getting hit at all? Even though that barrel is short, you will encounter some barrel whip.

TehLlama

06-19-12, 01:19

Are you concerened about the rail getting hit at all? Even though that barrel is short, you will encounter some barrel whip.

If that presents itself, shouldn't hurt rail rigidity much to shorten that inside 1.5" just a bit, but that's a touch expensive, and that might just work perfectly.

GlocksInMySocks

06-19-12, 09:59

QuietShootr

06-19-12, 10:01

Isn't there a certain level on of concern that should be taken with using a crush washer? I was under the impression that you run the risk of baffle strikes with a crush washer and have always used shims.

I have $20 that says OP will have a baffle strike and ****ed-up endcap within the first 500 rounds.

Jer

06-19-12, 11:12

That's hellaflush bro! :D

Nice work! :cool:

BTW, I'm pretty sure crush washers are a no no when mounting suppressors as they can sag under extreme heat and could potentially lead to baffle strikes.

Cameron

06-19-12, 12:29

Are you concerened about the rail getting hit at all? Even though that barrel is short, you will encounter some barrel whip.

Not overly concerned, the LMT 10.5" is quite a heavy profile and the barrel/rail would have to make a big flex before the barrel contacted the rail. I will let you know if it causes any problems.

Isn't there a certain level on of concern that should be taken with using a crush washer? I was under the impression that you run the risk of baffle strikes with a crush washer and have always used shims.

I have $20 that says OP will have a baffle strike and ****ed-up endcap within the first 500 rounds.

You guys are right, we shouldn't use a crush washer when mounting a suppressor. We did mock this up using the factory crush washer to see if it would fit. As everything appears good we are going to re-install the can using shims and blue locktite, as prescribed by Gemtech.

Should have the can setup correctly today so I can get to the range later this week and get it a try...

Cameron

WS6

06-19-12, 16:35

To me, this is very reminiscent of the "VIP Status" trend popular in some areas.

http://www.gtspirit.com/wp-content/uploads/2010/04/overkill_tuned_vip_car_off_camber.jpg

I mean, it may look good to some people, but to me, it just doesn't look like it was made for anything but looking at. The use of blue loctite, which will be rendered completely useless after the first theoretical magazine is emptied slow-fire, confirms the "look but don't use" concept.

Money to burn? Why not. I hope I'm wrong, but I see nothing good coming of this aside from "Hellaflush, VIP style" type internet pix.

Dano5326

06-19-12, 16:42

I would NOT use a crush washer.

At best you will have more significant POA/POA shift when can is on. At worst, catastrophic failure.

Even if it works initially, the extreme heat can cause fatigue and unknown results down the road. A 30cent crush washer not made to protect an $800 can.

Cameron

06-19-12, 17:07

To me, this is very reminiscent of the "VIP Status" trend popular in some areas.

Money to burn? Why not. I hope I'm wrong, but I see nothing good coming of this aside from "Hellaflush, VIP style" type internet pix.
Hop off your high horse mate. It is nothing more than a suppressor mounted directly to the barrel and a longer rail.

I would NOT use a crush washer.
You guys read above where we mocked it up for fit using the factory crush washer right?

You guys are right, we shouldn't use a crush washer when mounting a suppressor. We did mock this up using the factory crush washer to see if it would fit. As everything appears good we are going to re-install the can using shims and blue locktite, as prescribed by Gemtech.
It has now been reinstalled with a shim and locktitied in place following Gemtech's instructions. I will let you know how it works.

Because the suppressor aligns on the muzzle threads and against the shoulder at the rear of the muzzle threads, it is of utmost importance to be certain that the suppressor is at all times screwed tightly onto the muzzle of the weapon. We recommend the use of “Blue” Loctite on the threads when mounting the suppressor.
Do not use any type lockwasher or the factory crush washer. Lockwashers or the crush washer will cause misalignment.

Cameron

WS6

06-19-12, 17:10

Hop off your high horse mate. It is nothing more than a suppressor mounted directly to the barrel and a longer rail that it clears...

Cameron

You went to extra trouble for something that offers absolutely no functional benefit--and might cause issues--just because you like how it looks.

I don't think I'm wrong on the facts, here, or in relating it to the "VIP status" or "hellaflush" trends going on with cars.

PS. Get rid of the blue loctite. It's as useful as spit for this application.
http://tds.loctite.com/tds5/docs/242-EN.pdf
View the graph titled "Hot Strength Tested at temperature" and extrapolate from there on the temperature. Then factor in heat cycling, etc. Loctite 242 is not recommended for this application, or any other involving this kind of heat.

Cameron

06-19-12, 17:20

I think you are missing something, it is just an SBR with a can. What extra effort trouble did we have? All I wanted was a can that fits and clears the 10" rail, and it does, with the addition of a basic shim. Where is the trouble and the extra problem?

I have used blue loctite on suppressors for years without any issues. I think I have owned and used more than 20 suppressors on firearms from .22 to .30-06 in the past 20+ years. I think I got my first can when I was 8...

Cameron

WS6

06-19-12, 17:22

JeepDriver

06-19-12, 17:46

Looks damn good.

I was starting to think I was the only one who owned an M4-02, I've never seen another one on various gun forums.

fallenromeo

06-20-12, 17:37

very nice setup man. When are you taking it out?

usmcvet

06-22-12, 10:20

Cameron,

Any update. Oh by the way I hate you! A can at 8, Okay not hate just jealous.

Cameron

06-22-12, 11:06

Cameron,

Any update. Oh by the way I hate you! A can at 8, Okay not hate just jealous.

It runs like a champ. I put about 120 rounds on M193 through it yesterday afternoon with out an issue and the can stayed nice and tight, which is great because once they get hot that are tough to re-tighten even with good gloves on.

BTW in New Zealand, where I grew up, cans are unregulated and we use them on everything.

Cameron

usmcvet

06-22-12, 11:49

It runs like a champ. I put about 120 rounds on M193 through it yesterday afternoon with out an issue and the can stayed nice and tight, which is great because once they get hot that are tough to re-tighten even with good gloves on.

BTW in New Zealand, where I grew up, cans are unregulated and we use them on everything.

Cameron

Good to hear. Yeah I wish we could get our shit together here in VT. I used a can this week with my kids, 7 & 9 and it was awesome, we brought eyes and ears to the range but when we were alone and shooting just the .22 with the can no ears were necessary and it was a lot more fun especially in the heat.

J Krammes

06-22-12, 20:38

Looks good... I like it.

How regulated are guns in NZ? I have always wanted to go there.

Jeremy

WS6

06-22-12, 20:45

Looks good... I like it.

How regulated are guns in NZ? I have always wanted to go there.

Jeremy

Lots of licensure. You need separate endorsements for each type, and to belong to a club, etc. Similar to a cdl and other specialized auto licenses in the us, as I understand. I looked into it a while back briefly.

Cameron

06-24-12, 11:59

I have $20 that says OP will have a baffle strike and ****ed-up endcap within the first 500 rounds.

Do you want to send a check or PayPal??

Shot 400+ rounds this AM zero problems, for a total of more than 550 rounds with no issues.

3MOA of POI shift to 6 o'clock from the A2 flash hider to the barrel mounted can with M193 and M855. Shot a couple of very nice 1.25-1.5" groups using Hornady TAP 75gr, and the EOTech at 100yds.

Here she is after the range session.

http://farm8.staticflickr.com/7278/7435336888_3052cc3303_b.jpg

http://farm8.staticflickr.com/7118/7435294634_6b0a5aacaa_b.jpg

QuietShootr

06-24-12, 18:48

PMO is how I roll, wiseguy. PM me your address.

ETA: Back it up. You shot 550 rounds on a crush washer, or with proper shims? If you shot it with shims I don't owe you shit.

Do you want to send a check or PayPal??

Shot 400+ rounds this AM zero problems, for a total of more than 550 rounds with no issues.

3MOA of POI shift to 6 o'clock from the A2 flash hider to the barrel mounted can with M193 and M855. Shot a couple of very nice 1.25-1.5" groups using Hornady TAP 75gr, and the EOTech at 100yds.

Here she is after the range session.

http://farm8.staticflickr.com/7278/7435336888_3052cc3303_b.jpg

http://farm8.staticflickr.com/7118/7435294634_6b0a5aacaa_b.jpg

Eurodriver

06-24-12, 20:18

So in.

E-man930

06-27-12, 15:47

Cameron ruined my "I got my can to fit super close" thread that I had planned on starting once I got my stamp back... here is a pic of it at the class 3 dealer for test fitting. :D

http://img11.imageshack.us/img11/2899/canssgc01.jpg

Cameron

06-27-12, 15:52

Cameron ruined my "I got my can to fit super close" thread that I had planned on starting once I got my stamp back... here is a pic of it at the class 3 dealer for test fitting. :D

Looks good. What are the rail, barrel and can?

Cameron

E-man930

06-27-12, 16:06

Its a Knight's SR-15 11.5" factory SBR upper (URX II) with an AAC 7.62 SDN-6 mounted on their (AAC) two port muzzle brake. I used the crush washer that came with the upper and milled down about 1/32" off of both sides to give it some flats; I hope this will better stabilize the brake on the barrel shoulder... I then attached the muzzle brake (with plenty of rocksett) which timed properly with only about 60 degrees of rotation after hand tightening. Lucky for me, my SDN-6 locks up dead solid on the 51T AAC mount.

Hope this helps, E-man

E-man930

06-27-12, 16:23

Here is a shot the rail / barrel / brake without the can.

http://img31.imageshack.us/img31/2408/sbrbrake.jpg

Hope this helps, E-man

Cameron

06-27-12, 17:14

E-man930

06-27-12, 17:27

Thanks Cameron - I'm going to run it as it is once I get my can and just keep an eye on everything. The flats I milled in to the washer show to be squarely seated 360 degrees around both the shoulder side and muzzle brake side of the washer. I could see that cranking on one 270 or 360 degrees could result in some deformation that could alter the bore / line axis of the muzzle device and suppressor assembly. I figure I also have a little leeway by using a 7.62 can on a 5.56 gun; my initial assessment of the mount is that it is square and solid. I do have a pair of dial indicators and some magnetic fixtures that if one day I decide I have to see how concentric the mount is to the bore I can pull the barrel and check.

Jer

06-27-12, 18:22

That looks great.

Like some of the previous guys mentioned here, the use of a crush washer is strongly discouraged by the can makers. That said I don't know what "milling down about 1/32" off of both sides to give it some flats" did to the crush washer. I understand it is the deformation of the crush washer that can cause bad can alignment. To that end I had my guy use a shim rather than the crush washer, and everything seems to be running great.

Looks awesome though!

Cameron

It's actually the material of the crush washers themselves. It's really soft (hence the 'crush' part) and when heated they can compress/sag even further, especially when you have a can hanging off of the end. The can is going to want to sag due to gravity so the weight of the can will rest against the bottom portion of the crush washer. When you heat things up this can compress even further which could allow your can to drop against the threads however much they allow. Doesn't sound like much but when you realize how much clearance there is in this whole setup any little bit of sag at the base of the can can translate to much more movement off of center by the time you get clear out to the business end of the can. This is why most users (all manufacturers) will recommend using a peel washer or solid shim turned to the proper thickness for clocking of a muzzle brake as oppose to a crush washer. Takes one more potential variable out of the equation.

Not sure if we're wandering OT or if anyone even cares but there you go. :p

J Krammes

06-27-12, 19:39

A shim kit from AAC is only $5... You know they are flat are made for exactly what you want to do. Buy two while your at it. A hell of alot cheaper than an SDN-6. They are showing out of stock at the moment, but keep looking till you get an approval. http://www.advanced-armament.com/product.aspx?pid=719#pid=719

Jeremy

E-man930

06-28-12, 07:08

Thanks for the advice guys (and sorry for the thread derail OP) - I have two sets of KAC shim kits that I have not yet opened. I did debate using them instead of the modified crush washer (which neither crushed nor is made of soft metal - at least not the version that KAC used) but did not like the idea of stacking up about 8 - 10 shims made up of softer aluminum. When I was machining the CW, it seemed as though it had a heat treat and was a little harder than the steel my barrel is made of... just food for thought. Not all crush washers are created equal thus the blanket statement from can manufacturers to remove liability for end user install mistakes. Also, I don't see how the can will magically cause the muzzle break to sag. In my particular case, the threads on the barrel and threads on the muzzle break had a very close, almost interference fit and there was literally no play when I was screwing it on. If I were to have threaded it on half of the way and left it like that and then attached the can there would be virtually no measurable deflection in the entire assembly. So in reality, I'm not too worried about my setup for the time being. Think of my crush washer as a modified steel spacer if you have trouble sleeping on my behalf.

Cameron

06-28-12, 10:14

if you have trouble sleeping on my behalf.

:D there are a lot of guys on here that are DEEPLY concerned for your and my well being mate!!

I like how you got the result with the ability to be able to quickly remove the can. I was looking at a Surefire or AAC can with a brake mount before I had access to the Gemtech. I will be looking at getting a couple of new cans from SF or AAC in the future, and would like to have a nice close mount on this 10.5" and my 11.5".

Post up a pic of how the whole carbine looks if you can.

Top BCM 11.5" with Gemtech HVT bi-lock
Bottom LMT 10.5" with Gemtech M4-02 barrel mount
http://farm9.staticflickr.com/8153/7461315468_b62afe6106_b.jpg

http://farm8.staticflickr.com/7131/7461314040_4807bf57f4_b.jpg

Cameron

E-man930

06-28-12, 16:56

10-4
Here are the pics...
I broke out the SLR to capture my 11.5" SBR on the mandatory, weather beaten deck... Hope you guys enjoy.

http://www.pictureshack.us/images/35070_SBR_V3_KAC_E3_11-5-001.JPG (http://www.pictureshack.us/)

http://www.pictureshack.us/images/7464_SBR_V3_KAC_E3_11-5-002.JPG (http://www.pictureshack.us/)