ASE UTRA sl5i bore sizing

[Jagged77]

Reviews and Tests – Edinburgh Rifles

The single most significant variable in sound attenuation is radial clearance between bore and bullet
Whilst the Mk1 ear hole may not pick up the difference I can catagorically state its a huge difference

I run all my mods "out of spec" because the threads have been done by us and/or checked for concentricity to the bore
tight spec thread, proper undercut, perpendicular shoulder etc etc

One of my current mods is a DPT .22 baffled OB on my 6.5Grendel
Bore 0.272"/6.89mm - Radial clearance - 0.004"/0.195mm (Several hundred rounds, no swipes or strike, extremely quiet)

Malxwal's mod above presents the following
0.265" Bore - 0.257" bullet - 0.004" radial clearance

Concentric threads are a bit of a sore spot having just spent £100 to sort one out Ed, but point taken thst the tighter you can go the better the sound performance. Still I’d rather have some play with a slighter over sized mod bore for reasons already stated.

 

[kenbro]

Just make sure you keep checking the mod is tight on. I fluffed up and it cost me a new mod.

At the best, even if you don’t get a strike it spoils a group if target shooting when mods loosen.
I’d ban 1/2” x 20 threads.
Ken.

 

[jb1]

At the best, even if you don’t get a strike it spoils a group if target shooting when mods loosen.
I’d ban 1/2” x 20 threads.
Ken.

It was or is an 18 x1 spigot, I was on steel at 1200, then lost it. Came back to 750 and still not on. Oh dear check mod, and about 1/2 a turn loose. Packed up for the day.