Understanding thread specs

[deepcore]

I have a Savage 12 with a threaded barrel (1/2-28) and a (what I measured as) .681 inch outside diameter where the threads end.

Will any muzzle break/compensator that has thread specs of 1/2-28 fit?

I see 'breaks with different outside diameter specs and is that only a reference to how big the compensator is compared to your barrel?

So a 'break that is 1/2-28 .920 OD will look huge on my barrel and one that is 1/2-28 .750 will look "better".

Or do all three variables ("1/2" and "28" and ".681") have to match? I can't find a comp with OD specs of .681.

 

[dahermit]

The 1/2 inch is the nominal outside dimension of the threaded part. The 28 is the number of threads per inch. Any thing that has a internal thread pitch of 1/2-28 should fit it. If you measured the thread pitch correctly, that is all you have to worry about.

 

[T. O'Heir]

Hi. The 1/2-28 is the thread shank diameter and the number of threads per inch. As long as the 'female'(Exactly what you're thinking. Inside and outside) threads are 1/2-28 the brake(not break) will screw on. Think in terms of a nut and bolt. A 1/2-28 nut will go onto any 1/2-28 bolt.
The OD of a brake doesn't really matter much. However, a .920 OD brake isn't much bigger than .681". Only .239" bigger. The brake will likely be tapered on the aft end to match the barrel diameter or can be machined to be. There are some daft OD's for brakes though.
What a brake looks like on the barrel doesn't mean anything either. You will find that the muzzle blast goes up with a brake. A brake sends the gasses and hence the blast and noise towards the shooter and anybody near him.
The calibre of a Savage 12 and which one you have makes a difference too. A .308 M12 is a 10 to 12 lb. rifle. A brake won't make a lot of difference. Complete waste of money for a varmint calibre. It'd just make it loud.
A compensator is a different thing altogether. Usually a pistol add-on thing that sends the gasses up.