Originally posted by TOM.32 from the old AR15.com board back in July of 2000:


I finally took the time to chrono different barrels for each length that I have and some different ammo just to see what the results would be. No real surprises.
Chronograph,
Oehler Model 35 w/ 3 screens
distance 10'
10 shots each barrel with each make of ammo

85 degrees
40% humidity (approx.)
1290' above msl

Barrels,
20" Colt 1/7 Govt.
16" Colt 1/9 lightweight
14.5" Colt 1/7 M4
11.5" Colt 1/7 commando
10.25" Colt 1/9 lightweight (16" cut down)

Lake City M193 1997
20" - 3255 fps
16" - 3145 fps
14.5" - 3075 fps
11.5" - 2884 fps
10.25 - 2767 fps

Q3131A 1999 Lot PF20
20" - 3152 fps
16" - 3051 fps
14.5" - 2951 fps
11.5" - 2732 fps
10.25" - 2605 fps

IMI M193
20" - 3131 fps
16" - 3032 fps
14.5" - 2917 fps
11.5" - 2726 fps
10.25" - 2598 fps

Rem UMC
20" - 3122 fps
16" - 3001 fps
14.5" - 2878 fps
11.5" - 2705 fps
10.25" - 2499 fps

No misfires, ftf's, chambering, or extraction/ejection problems.

Individual results may vary. I have done a few barrels at other times when it was colder (55 degrees and 70 degrees) and the Lake City was closer to the others in velocity. It seems like I read somewhere that the powder used is more temperature sensitive? I thought about doing some Lake City M855 but didn't think I would have time. Might try that next time.

Troy: What Winchester ammo is that 55grn? Is that Q3131A?