QD mount muzzle brake mounting

[pdsmith505]

I'm adding a YHM QD muzzle brake in anticipation of a suppressor and I had a question about mounting the brake.

Is there any problem with using a crush washer instead of the shims provided with the mount? Such as misalignment with the bore?

Thanks!

 

[Theohazard]

Whatever you do, never use a crush washer. You're completly correct that it can cause misalignment issues. Only use the supplied shims; they're precisely machined and designed specifically for the purpose. And even then, it's a good idea to use as few shims as possible. Three shims is the max I would ever use.

 

[HRnightmare]

I have the YHM phantom SS .30 and 5.56 and neither came with shims. Neither needed it either. What are you putting it on?

 

[pdsmith505]

Theo:

Good to hear my intuition was correct... I used the shims. Should I go out and buy some Rockset and re-mount?

HR:
I have the muzzle brake variety of QD suppressor mounts that require timing to align the ports for when you shoot without the suppressor.

The 5.56 brake is going on my 20" Palmetto CHF AR and the .30 brake is going on an upcoming .300 BLK pistol build. The can will be a .30 caliber Form 1 used on both.

 

[Captains1911]

I have a YHM .30 QD muzzle brake, used a few shims to time it properly, no rockset, just proper torque, and it has not moved yet.

 

[bikemutt]

I'll throw this out just in case the OP has plans to do what I did. I installed a YHM Phantom QD suppressor mount on my 7.62x39 upper. Everything went well for the first couple of range visits, then the rifle started patterning instead of grouping. It got worse the more I fired it, with or without the suppressor.

Before giving up on the upper I had my 'smith wrench off the QD mount. Turns out there's a cavity between the QD mount's end-of-thread and the actual tunnel out of the device. This allowed a serious carbon build up that adhered itself to the mount and the muzzle crown. And, it was not symmetrical, it formed at about the 2 o'clock position.

Anyway, I removed the carbon build-up from the muzzle and took the rifle back to the range naked; it put up 1/2" 5-shot groups at 50 yards "just like the old days". With cheap bloc ammo.

I suspect the dirty nature of 7.62x39 is the culprit but I'm now suspicious of this particular QD mount on my other rifles, chamberings ranging from 5.56 to 7.62.

In any event, I just installed a JP brake on the 7.62x39 upper planning to enjoy it's relative accuracy rather than it's quiet, scatter-gun side

 

[pdsmith505]

That is an interesting turn of events for sure, but I'm more or less locked into the YHM QD mechanism now, and use the muzzle brakes as something of a sacrificial blast baffle in my simple freeze-plug form 1 build.