Barrel harmonics and acceptable tolerance with free floating rails

[jMarine]

So I have KAC URX 3.1 rail I am going to install in my LR308. The barrel is a 16”Noveske N6 barrel which is a medium contour barrel. I am running the Noveske switchblock GB. My question is, how much or how little clearance is good enough to not allow contact with the rail and GB. I am willing to slightly alter the rail to prevent any accidental contact but I don't want to if I don’t have to (for obvious reasons. I don’t wanna “alter” a high dollar KAC part). I’m confident the rail is sturdy enough to not flex but It is possible to flex the barrel until they make contact.

I’m sure some will say, this rail will prevent you from even using the switchblock to its capacity… which is true… that being said, I am open to a GB that better suits my build.

Here’s a pic of the clearance I have. I can get an actual measurement if that makes it more perceivable.

 

[strikeeagle1]

Place some Dykem on one side of the tolerance parts and run the gun. Observe the result , impact or not; answered.

 

[sinister]

Looks like it clears to me. If it doesn't contact before the bullet leaves the barrel you're fine.

Dykem would let you know if it's hitting. Group size will tell you if it's before bullet un-corking.

 

[jMarine]

Great idea! I’ve got some permablue that should work. The sole issue with this is… the whole mounting and unmounting of the handguard since it requires the proprietary KAC sr-25 URX barrel nut wrench. I don’t own the wrench so I’m limited on that aspect.

 

[sinister]

I'd trim that little dingus lock-switch finger thingy -- but then, how does it allow the lever to select between suppressed-unsuppressed? Is there room to clear?

 

[jMarine]

I'd trim that little dingus lock-switch finger thingy -- but then, how does it allow the lever to select between suppressed-unsuppressed? Is there room to clear?

Yeah that’s part of the dilemma. So this rail will prohibit me from actually adjusting the block but, I won’t need to adjust it as I run an OSS can and the “suppressed” setting does not cycle the gun properly… at this point I’m sure the consensus would be “hey dumbass, just run a normal block then?”.. and I would… but I appreciate the fact this GB is pinned and I’m not sure there would be a third party GB that would line up properly. Maybe there is and maybe I’m way over thinking this… who knows.

 

[sinister]

You could always cut off the cantilever diving board.

 

[jMarine]

You could always cut off the cantilever diving board.

Ha! I’ve debated that but man that makes me blue!! I might just swap out for a superlative though. I have no clue what I wanna do

 

[Desert_Racer]

You could always cut off the cantilever diving board.

This. If you have a table bandsaw and a means of pushing the rail through straight, this is easy work. I did it with a DD RIS II rail last week.

 

[UpSideDown]

I like the Superlative block. It’s easy to adjust from the front with a wrench and lets you dial things in nicely.

You could do any number of reasonable things. Relieve some material with a dreamer or die grinder from the rail, cut the rail shorter, get a new rail, get a new gas block, shoot it and see what happens. That fitment is too close for my comfort.