I started building my 300 blackout today. Never built an upper before. When I ordered my barrel and other parts I got everything at once. Everything was ordered from SOTA. Barrel, upper, low profile gas block, tube, A2 style flash hinder etc.

I went and put my washer on, them the flash hinder, it was lined up and clocked right but still lose. I knew I needed to tighten it up some made it almost a full turn around and it felt tight but needed to go a few more degrees. I went to tighten it more and snapped my washer. A co-worker of mine use to be an armorer in the marines took a look at my barrel and flash hinder, and washer and said it was a bad set up and that it will keep happening if I used the same set up, and that I need to find stainless steel type washers.

Has anyone else ran in to this, or know what I should be looking for. I found a couple sites that have some listed but I want to make sure I am getting the right thing for one. And two I am trying to find some where that has the washer(s) I need along with the magpul flip front and rear sights. Then Ill be ready to go shooting.

Thanks for any and all help

Shims

http://www.brownells.com/rifle-parts/muzzle-devices/muzzle-brakes/ar-15-m16-ar-style-308-muzzle-device-alignment-shims-prod38890.aspx

Thanks I was looking on their site and wound something like that but I think it had like 25 shims or something in the package.

The shims come in a variety of thicknesses, so there will be way more than you need.

Were you re-using an old crush washer?  The only time I have thrown a shim under a crush washer is when I am re-using it.  A new crush washer should get you about a turn and a half before it bottoms out and even comes close to splitting.

No I was no using a used washer. Everything was new out of package. When I was putting it all together and screwed it on by hand it was clocked right, I know I still needed to tighten it got nearly a full turn and it was a couple degrees off. I tried to get it the rest of the way but it snapped.

I ordered the shims that where in the link provided this morning. So I hope Ill be able to have everything together soon.

You don't use a crush washer with the shims, it's one or the other.

It doesn't matter.  It started off being a shim system, then transitioned to a crush washer system.  There is nothing wrong with using shims to give you the timing starting point that you desire.

Warhawk, thanks for the advice. Got them in today after what seemed forever. Got everything thing together, they worked out great. Time to find a little more ammo and go brake it in.