Do the muzzle devices get tighter as you fire rounds? I noticed that my rifling is a RH twist. Why did Klashnikov decide to go with 14mm x 1 LH?

There is a detent pin that prevents movement of the muzzle device

My Vepr does not have a detent pin nor is there any way to install one. That said, I have read about a few people with loose muzzle devices USING the detent pin.  On the AR15, you can depend on a lock washer, peel washer, or crush washer to help time or retain the muzzle device. I don't see the detent pin providing the same type of retention, so there must be something else at work. The detent pin will prevent the muzzle device from working itself loose, but there's nothing there to prevent the threads from being beat up due to vibration.

I don't quite understand how the Vortex tightens by itself, considering the rifling is typically a RH twist. I'm not sure why klashnikov chose 14mm x 1 LH either.

Some threads are left hand like the 14x1, and others are right hand like Romanian 22mm, Buly/Russian 24mm, and Yugo 25mm or whatever it is. Only a detent pin holds the devices on.

So some of the devices just rattle around relying on the detent pin to hold it in place?

Quoted: So some of the devices just rattle around relying on the detent pin to hold it in place?

Some do depending on how tight the fit is.

Wouldn't this cause excessive wear on the threads when using a muzzle brake? I would imagine the vibration can slowly wear down the threads or perhaps even elongate the channel in the FSB for the detent pin.

Quoted: Wouldn't this cause excessive wear on the threads when using a muzzle brake? I would imagine the vibration can slowly wear down the threads or perhaps even elongate the channel in the FSB for the detent pin.

You must plan on shooting a lot of rounds Ive never heard of this being a problem & doubt its really a issue. Even if it doesnt lock on tightly against the FSB its still not exactly flooping around. If it bothers you just take the end of the brake & slowly file it untill it fits snugly against the FSB. Or you could just add a drop of lock tite