I have “several” 14.5" barrels that I’ve decide to pin & weld, I’ll wait for further rulings on SBR’s for some, but in the meantime I will do the p&w. So, what is the general consensus on shims vs the crush washer? I would prefer shims, as I’ve read in some instances, that after welding, the crush washer is loose. Thoughts?
shims always, the days of the crush washer are dead to me because they dont crush evenly which means your MD could not be straight and now you have a pinned MD thats throwing your accuracy off.
I had one that got wobbly on me. Not sure if it took a whack, or heat cycling or what. Shame is, I gave it to a “gunsmith” already secured with a shim, with instructions not to replace it, and he did anyway. Its one of the numerous reasons I am distrustful of gunsmiths, and would rather hand an upper to a guy at a body shop.
Anyway…shims.
Shims 100%. Especially if you ever want to suppress it. Better safe than sorry.
Same. I stopped using anything else.
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Throw all your crush washers in the trash, they’re only used to save time in mass assembly. Take the time and do it right with shims.
Another vote for shims or accu washers, especially it you’re pinning a suppressor mount.
That almost makes sense lol.
Thanks for the responses. I thought the same, but I do see crush washers still being used. Shims just seem correct for something that basically won’t be taken apart.
I want to be an ass and lobby for the crush washer. I just can’t though.
I leave them on barrels that come with them, but never use them If I’m mounting a bird cage.
Are the Accu washers beveled on the internal end that goes against the barrel? Or does that not matter?
They have the edges broken on the inside diameter. Call it a very small chamfer.
Dunno if I would call it a ‘bevel’ in the same way that barrel makers use that term to describe their threads.
The washer will cone-out a small amount as you torque against it. To flatten against the shoulder of the barrel. Won’t work with any real taper or other non-spec geometries going on.
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I have had trouble with accu-washers on some barrels. The accu-washers will not sit flush against the shoulder unless I bevel the aft edge of the hole by hand.
Another consideration is that most shims are stainless, and the various types of stainless are far from carbon steel in the galvanic series (austenitic stainless more than martensitic). This could cause some galvanic corrosion in the long term, as the phosphate finish on the barrel shoulder and the flash hider can be rubbed off by the torquing process.
Thats why the first washer you’re supposed to use in the Surefire shim pack is beveled.
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they should never be used on any baffle style muzzle device where the clearance hole is only slightly larger than the bullet
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I stick with regular shims for anything that may ever seen suppressor use. Even if I don’t own the can for a particular mount, if it is a mount for a can, its getting a shim. Above, I think the position of Precision Armament is pretty clear, there washers are not recommended for suppressor use.
To be clear, they are talking about crush washers in that quote. They specifically claim that their product reduces the risk of baffle strikes.
That is correct.
Another vote for the Accu-Washers. They’re all I use any more. Here’s what Precision Armament says about using them with a suppressor:
Since only one shim is required, the tolerance stackups and complexities associated with peel washers and other multi-shim systems are eliminated. This minimizes the risk of baffle strikes, ensuring maximum accuracy and safety from your muzzle brake or suppressor.
Odd guy out here. If a SF mount then shims, if M4 14.5 type with A2X crush washers are fine…