Can a YHM phantom brake suppressor mount be installed on a SCAR 17 using the factory jam nut screwed down lightly but firmly on the miniscule shoulder?

Silencershop's list of mounts they tried on a SCAR 17 barrel says this mount will work with no additional parts needed, but is utilizing the jam nut or the PMM washer a better install?

I guess my question is the FN jam nut a precision part with a perpendicular face or not?

Thanks!

I've got a YHM Phantom 762 M2 QD SS. I wasn't really pleased with the accuracy performane, seemed to hurt my 17s accuracy.  The standard Phantom flash hider works fine just screwing it down as it seats on the muzzle, not the shoulder. If you use the QD brake you'll have to time it with peel washers. I have used my TBAC 30P-1 on my 17s using the jam nut, shot fine with good accuracy but I was always a little nervous with that setup. I've finally settled on the TBAC Ultra 7 with their QD flash hider, love this setup.

I went ahead and mounted my YHM suppressor using the FN supplied jam nut, but carefully and lightly seated on the barrel's tapered seat. I used a Phantom muzzle brake mount, blue loctited and torqued carefully. I use a silver sharpie to make small witness marks so I can see if anything is loosening.

Looked thru the bore and it looked clear and the suppressor centered. Shot it with no problems apparent.

Even though the suppressor mount looked to be centered using the FN jam nut, I found a specialty washer for suppressor mounting at PMM and ordered it. Remounted the suppressor mount with some blue loctite.
This seems like a better solution so far with no issues noted.