I couldn't imagine them wearing to an unserviceable state before the barrel was shot out and needing replacement...that said I'm no expert

-HKBJJ

 

Presuming you don't try and abuse the 3 lug, I'd say whatever attachment you are using on the 3 lug will wear out 20 times over before the barrel lugs are too far out of spec to hold attachment #21.

 

no they will not

 

Just be sure to remove the HK flash hider periodically to clean. Carbon builds up and the FH can seize onto the 3 lug making it almost impossible to remove. You can damage both. I've seen once on PD gun.

 

Just the paint/ coating.

 

Gotcha. I've got an HK-made barrel on my SW5 and I've noticed the parkerizing has been coming off with continued use. I assume that the metal of the barrel is probably tougher than the metal in the 3-lug mount.

 

I had a rental MP5 at a shooting range that I put over 75,000 round through with a Gemtech Raptor. The rifling was getting thin but the 3 lug is fine. It needs to be cleaned occasionally or is about impossible to get off.