Trouble timing muzzle brake

[TNMTBik3r]

Got home from work today and the last couple parts I needed to complete my 6.8 AR were here, so decided to finish out the upper tonight.

 

I cannot get the muzzle brake even close to timed with or without the crush washer so looking for opinions.

 

 

16" 6.8 barrel from AR15Performance, 5/8-24 threads. Barrel is nitride finished.

YHM .308 slant muzzle brake with crush washer: http://yhm.net/30-cal-muzzle-brake-308.html

 

 

"Times" are based on the top of the barrel with the gas port being 12:00, top of the brake in correlation.

Using a bench mounted vise, tried rubber vise jaws and a leather belt wrapped around the barrel - the belt helped a lot more than the vise jaws.

 

 

With the crush washer installed correctly (the "bowl" facing the muzzle device) the brake hand tightens to about 2:00. Clamped in the vise with the belt, I was able to wrench the brake to 5:00. At that point the barrel/receiver began spinning.

 

With the crush washer installed backwards, hand tightened to 4:00 and able to wrench to not quite 7:00 before barrel/receiver began spinning.

 

With no crush washer, hand tightened to 6:00. I did not try and wrench tighten and risk any damage due to the half revolution needed.

 

 

I know not to use an upper receiver vise as it could result in the barrel pin being sheared. I am using a 4" vise mounted to an 8 foot bench, tightening down on the vise with all of my weight. Leather belt wrapped with the rough side against the barrel, part of the issue may be the slick nitride finish?

 

It looks like my options are to:

1. Get a muzzle device shim set

2. Take it to the local gunsmith

3. New muzzle device

 

Any other ideas or suggestions? I really thought the leather belt would have provided enough grip...

[TNMTBik3r]

I really think the nitride finish is a contributing factor. Haven't had an issue when swapping out the muzzle device on my other ARs, but they were phosphate and therefore rougher finish.

[TrickyNicky]

I used an upper receiver vise block to do my last A2 flash hider, it sure didn't seem like I was putting much at pressure at all to get it timed right. I thought about the barrel pin, but I was more concerned with the slot on the upper getting chewed up by the pin than getting sheared. I only needed to go from 6:00 to 12:00 so it was pretty easy going. If you'v got a torque wren I would put it in and see what you're working with resistance wise and if you feel comfortable, try and take it a bit tighter, since you've already crushed it a bit, I would bet you can go a bit further than before.

[TNMTBik3r]

I just read an article that suggested crushing the crush washer a bit more in the vise, then trying to install. Going to try that, seems so obvious but never crossed my mind.

 

I didn't put my torque wrench on but I can. It felt like I was using more pressure than when installed the barrel nut, which I had to torque to 45 foot pounds to align properly.

[Smith]

I've grown fond of jam nuts for just this reason. Keep several on hand. I have some for your 5/8x24 if you need one. Just pm me.

[TrickyNicky]

But I'd bet when you where putting on the barrel nut you had the whole thing viced up, so it feels like your putting more pressure on it now, but I'd bet a nickel it's not at 45lb. This is sounding exactly like how I felt prior to throwing it in the vise clamp lol I was stringing and fighting, then I put it in and aligned it with one hand as easy as turning a key in a lock.

[Clod Stomper]

In my experience, crush washers don't really crush. What I've done is to lay some sandpaper on a flat surface and take material off one side of the washer until it times correctly.

I'm going to find some real crush washers.

[TNMTBik3r]

Just put torque wrench on, hit 50 pounds before barrel spun in the leather belt.

I took it off,crushed the washer slightly with my vise, hit 50 pounds again on the wrench but the brake is at 9:00

[gregintenn]

Thin the washer with a sanding block.

[RED333]

Thin the washer with a sanding block.

 

 

In my experience, crush washers don't really crush. What I've done is to lay some sandpaper on a flat surface and take material off one side of the washer until it times correctly.

I'm going to find some real crush washers.

DO THIS!!!

[TNMTBik3r]

Woo hoo. Just needed people smarter than me.

Crushed the washer a bit in my vise, than ran both sides across some sandpaper for a few seconds. Finally got the brake to index correctly!

Thank you all!

Next time I will be checking into the jam nut to avoid this.

[Tobashadow]

Are you trying to do it in one pull on the wrench?

You have to pull till it just starts to get real tight then back off and do it again and again working your way around.

[TNMTBik3r]

Was working my way around, the issue was the barrel twisting when I hit 50 pounds of pressure on the wrench. Sanding down the crush washer did the trick though.

 

Pics coming in the Show & Tell forum in a few.

[dcloudy777]

Shim sets are cheap, and work well.