Using shims to time 51t brake

[doubleajaybrock]

Can you use too many shims to set the time? I have a PWS Mk110 mod1 (556) and I ended up needing to use some of the timing shims that came with the the upper the they used to time there Triad flash hider along with some of the AAC shims to set the timing and space it out a little to clear the rail. Is having the shims stacked .130" thick potentially cause any issues?

[Grounded]

That seems like a ton. I had to used about .025" or so to time mine. Is it because it won't thread down far enough? How about chasing the thread to let it thread on further. A pic would be worth a 1000 words here.

[doubleajaybrock]

I've already trimmed a little off the lower portion of the rail and don't real want to have to trim more unless it is really necessary.

[Grounded]

I've already trimmed a little off the lower portion of the rail and don't real want to have to trim more unless it is really necessary.

Doesn't look too bad. As long as the shoulder is square your good.

[Fulmen]

In theory you could stack shims to the moon without problems, in reality it's hard to predict. Each washer adds a bit of error, either from inaccuracy in the shims themselves or from debris trapped between them. And depending on alignment errors could either cancel each other out or add up. A single shim of the correct thickness would be better, but as long as it's a permanent setup and the brake/can aligns up correctly I think you're good to go.

[rjacobs]

I believe AAC recommends no more than 2 shims(might be 3).

[1_ar_newbie]

If those are all shims ans not washers from the hardware store you are good to go

Torque the mess out of it as you want all of the shims to be FLAT.

FYI a better way to do this is to email me and I will send you a pack of the thickest shim we make... that way you will only have 3-4 shims

[email protected]

[doubleajaybrock]

If those are all shims ans not washers from the hardware store you are good to go

Torque the mess out of it as you want all of the shims to be FLAT.

FYI a better way to do this is to email me and I will send you a pack of the thickest shim we make... that way you will only have 3-4 shims

[email protected]

Thanks Mike! Email sent.

Aaron

[Pman5KMO]

You want to have as much threading in contact as possible thus you want to use the minimal amount of shims possible to obtain proper clockinh/timing.

As others have said a shim made for this purpose should be rather precise and theoretically one could stack them 5" and be fine (if you had enough threading). I use the minimal amount because the less thread engagement you have the more stress that is place on those threads. With a properly threaded barrel you should have over 90% thread engagement. You want at least about 80% otherwise you are creating excess stress in the threads on the barrel . This can result in catastrophic failure.

[beanfield33]

AAC makes a blackout and brake that positions the teeth forward a few mm. If you're really concerned about alignment, that might be the way to go.




Or is that only for the .30 mount?

[doubleajaybrock]

AAC makes a blackout and brake that positions the teeth forward a few mm. If you're really concerned about alignment, that might be the way to go.




Or is that only for the .30 mount?

That's the 30 cal.

[doubleajaybrock]

We'll, I wasn't happy with all the shims so I broke out the grinder and got to work.

[Pman5KMO]

Thats probably the best/safest way to go... and what I would have done myself.

I prefer brakes over flash hiders when it comes to suppressor mounts. I RARELY shoot without a can. I want my cans to last and have found with brakes cans look newer far longer as far as baffle erosion go. Especially on short barrels brakes are known to increase suppressor life.

Performance wise I would love to see some testing with the same host and can with a brake and a flash hider (and possibly direct thread with a can like the saker) to check if there is a performance difference. I know first hand with 300 BLK there is a tone difference brakes giving a bit deeper tone. Of cpurse this varies with host caliber and can.

The one thing that is known is brakes act as a sacrificial blast baffle, this shines the most in short barrel high pressure calibers. Brakes do wear albeit slowly except in short barrels, and is noticeable on high round count weapons.

[este]

I really don't understand why anyone wants their can as absolutely close as possible.

I want no less than .5" in there. I have a full inch on my 12.5" and it's convenient to get the can on and off. ESP on a can like an AAC or SF where there is a latch to depress.

[doubleajaybrock]

I really don't understand why anyone wants their can as absolutely close as possible.

I want no less than .5" in there. I have a full inch on my 12.5" and it's convenient to get the can on and off. ESP on a can like an AAC or SF where there is a latch to depress.

That's how the rail came on the upper.

[57fairlane]

In theory you could stack shims to the moon without problems, in reality it's hard to predict. Each washer adds a bit of error, either from inaccuracy in the shims themselves or from debris trapped between them. And depending on alignment errors could either cancel each other out or add up. A single shim of the correct thickness would be better, but as long as it's a permanent setup and the brake/can aligns up correctly I think you're good to go.

you must be an engineer or machinist or both

[Fulmen]

What gave me away?