Shim Kit / Peel Washer Recommendation - BCM LW Barrels

[ScatmanCrothers]

I dont really want to get in the middle of this spat, but I would like to add a couple comments about the terms "soft" and "compressible". What we are really talking about is deformation. Do the washers deform when the muzzle device is tightened down? Absolutely. Elastic materials will deform under stress. They can either deform elastically or plastically.

I think the question we should be asking is what type of deformation is occuring. Elastic deformation is when you stress a material, it deforms, and comes back to its original shap when unloaded. A spring working in its intended range is a good example of this. Now take that spring and streatch it out beyond where it is intended. It will be permanantly deformed because you have exceeded the elastic limit and have plastically deformed the material. A crush washer is another good example of plastic deformation.

Edit to add: It seems to me that these washers are intended to work in the elastic range of the material, but I do not have experience with them yet.

They permanently deform. Once you've used one it's no longer to act like it originally did in the instruction's selection process.

[Tzook]

That shim kit from Precision Armament works well. Usually you can get a couple barrels out of one kit as well, I think I've done as many as 3 on one kit.

[markm]

I'm willing to bet that the precision shims are deforming to the shape of some of the annoying shoulder shapes on many barrels. That transition from the shoulder, between the threads often has a radius to it that flanges shims/washers.

[GH41]

I'm willing to bet that the precision shims are deforming to the shape of some of the annoying shoulder shapes on many barrels. That transition from the shoulder, between the threads often has a radius to it that flanges shims/washers.

Mark, I don't think they are deforming at all when torqued to the normal 20-30 FP. Some guys will never take their foot out of their mouth no matter how overwhelming the proof is that they are wrong.

[markm]

Possibly... I've never tried the precision kit.. But I've seen my thin AAC shims deform. Those are MUCH thinner than anything pictured in the precision kit.

[tommyrott]

I always put the thickest shim on the barrel end , I have only used AAC shims but have had zero problems. like the color coding= thickness helps getting the final adjustment

[ScatmanCrothers]

Mark, I don't think they are deforming at all when torqued to the normal 20-30 FP. Some guys will never take their foot out of their mouth no matter how overwhelming the proof is that they are wrong.

Man, you have really taken issue with this huh? Let me take my foot out of my mouth so that my endorsement for this excellent product that you also like doesn't rub you in such a wrong way. Or so someone can let me know where my understanding went wrong. The instructions advise that once you've selected the correct washer based on their provided chart to note that an additional 10-30 degrees of rotation is possible depending on the final tightening torque. Is it safe to assume that Precision Armament means 10-30 degrees of additional rotation that falls within recommended torque settings for a muzzle device on this platform? Surely they don't mention a 30 degree possibility that would require excessive force would they? I wouldn't think so. And why start at 10 and not 1? Minimal torque requirement, no?

Now seeing that each washer is in a 20 degree increment is it not correct to think that any of multiple consecutive sized washers would have the ability to work for a given muzzle device with up to 30 degrees of spin available when torquing? That's been my experience. Is that incorrect? They also note in the instructions that applying grease to the washer and threads will reduce friction and allow for further spinning for a particular torque load. They aren't recommending excessive torque values again are they?

On my first install I chose a washer that was too large to time the device correctly so I removed it because it came up short. When I started hand tightening the sizes around it I tried that particular used size again and it timed differently with hand tightening. Nothing drastic, but it had been permanently deformed and was now smaller. It was just an observation. I wouldn't be able to correctly use that size in conjunction with the graph. It is what it is. I don't know if it was because of the barrel, because of the washer, or a case of a sudden Herculean effort on my part with a torque wrench but it definitely deformed.

I also said that it was nice to be able to pick a washer to use minimal torque with rocksett for a suppressor mount. Again, minimal torque setting as in within the range of acceptable torque values for a MD on this platform. You decided to interpret that as slather on the rocksett with some hand tightening and off you go. That's not what I said and I thought the acceptable torque value thing would be understood in a discussion like this. Clearly I was wrong. I prefer to stay on the lower side of acceptable torque values myself and this set is great for letting you get that timing nice and close with hand tightening before torquing. Any issues here?

TL/DR, I know. Just genuinely interested in why you're so chapped by my first hand account comments.