Threading for a T3 Varmint Barrel?

[Slug870]

I am purchasing a muzzle brake for my T3 Varmint (6.5x55) and the manufacturer offers three different thread options for the brake M14x1.5, M15x1 and M18x1. Now I'm not gonna lie here; I have no idea which to choose or for what reason, so I am going to ask those with experience...

The brake can come with another thread upon special request, but again, without the knowledge of why one would be better than the other, I figure I may stick with one of the "stock" thread options.

My apologies if this belongs in the Gunsmithing forum, but I figure as it pertains to my Precision Rifle, I'd post it here...

 

[BigMofoFrog]

The T3 Tactical comes with a M18x1 threaded muzzle- same as SAKO. I suspect the Tactical and Varmint have the same barrel profile (haven't personally measured but they look the same). I've been looking for a different brake for mine and have found the metric threaded brakes are a little more scarce than the imperial here in north america.

 

[GunBoy]

The M14x1.5 is a no no, M15x1 is for HK metric , m18x1 is Sako trg muzzle brake. You can try to ask for 5/8 -24 TPI is use in north America as a very standard threading. Some gunsmith won't do metric thread, but is quite easy if you know what you doing.

 

[gunrunner8]

Aim for the largest dia of thread available for the reason that the least amount of material removed from outside the muzzle will not result in any however small bore enlargement....