[SRMohawk]

I know about the differences in terms of outside diameter and thread type, but are they the same length? I just received a Mil-Spec stock tube from Vltor and it's only a little over 7" long. Seems the commercial versions are at least an inch longer than this . . . a very desirable thing indeed if one is concerned about greater length of pull. I'm just not sure here and I don't have a commerical tube to make a side-by-side comparison!

[rcmodel]

There are carbine & rifle length tubes.

http://www.ar15barrels.com/tech/stocks.jpg

rc

[Onmilo]

Mil-Spec tubes are cut square atr the rear of the tube and commercial tubes are cut at a slant of about 45 degrees.
This does make the commercial tube about a half of an inch longer but it does not make the stocks extended length of pull any longer because the positioning of the stock locking detents is the same on the comercial and mil-spec tubes.HTH

[SRMohawk]

Very good. Thanx, Onmilo. Thought I might have been doing myself a disservice there for a minute opting for a stock upgrade on my M4 that incorporates a mil-spec tube.