Guys (and gals?), I just got a .22LR barrel from Spike's this afternoon. The barrel started it's life, presumably, as an M4-profiled barrel before it was cut down to an OAL of 9.75", re-threaded, re-crowned, and re-profiled "as small as possible, skinny as possible." The barrel looks pretty nice; however, the diameter under the handguard is ~0.690" which doesn't seem like much of an improvement over an M4-profiled bbl under the handguard. (Admittedly, the only other bbl I own, against which I can compare Spike's work, is on an LWRC 10.5" M6A2.) I'd give Spike's a call and ask them if ~0.690" is really the best they can do, but it's pretty late in FL right now; so, I was wondering if anyone with a Spike's lightweight dedicated .22LR upper receiver could tell me the diameter of their bbl under the handguard.

I don't know for sure but I believe that's as small as it gets. The entire barrel can't weigh much.
I haven't seen any barrel offered any smaller diameter or I'd sure have one....

SpecOps-13

You know, it's surprisingly hefty for its size. (To my, anyway; I'm a wimp.) I guess when I requested them to make it as thin as possible, I expected something different.

A 16" barrel, .680 taper to .580

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I have made many short barrels that are .580 - .700 full length

Nice barrel collection Retazdog!

I need to start another batch as one customer in FL purchased twenty 5" barrels at one time and now the collection is getting low

I'm feeling a 5.5" build in the future.
Does the 5" keep High Velocity sub sonic? I know the 5.5 wouldn't for me.

Bore size, chamber size and the temp outside can make some 5.5's go super more
the 5" does a better job with more brands of ammo.