Here is a shot the rail / barrel / brake without the can.
http://img31.imageshack.us/img31/2408/sbrbrake.jpg
Hope this helps, E-man
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Here is a shot the rail / barrel / brake without the can.
http://img31.imageshack.us/img31/2408/sbrbrake.jpg
Hope this helps, E-man
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
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.
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
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/pro...id=719#pid=719
Jeremy
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.
: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/8153/7...2afe6106_b.jpg
http://farm8.staticflickr.com/7131/7...07bf57f4_b.jpg
Cameron
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/35...3_11-5-001.JPG
http://www.pictureshack.us/images/74...3_11-5-002.JPG
Very nice!
I forgot you didn't have the can yet. I like it and I am thinking of picking up a couple of the Surefire mags too....
What's the texturing on the underside of the UBR??
Cameron
Thanks man... I just got stipple happy with my variable voltage / temp soldering station. I grip it there when I adjust it's LOP so I figured what the hell.