Accuracy Evaluation of a Noveske 18” SPR Barrel
Noveske’s 18” SPR barrel is a stainless-steel barrel that has a medium contour and a 0.750” diameter gas block journal. The gas block journal for this barrel is designed for Noveske’s low profile gas block and the journal is only one inch in length; standard length gas blocks will not work with this barrel. Fortunately, Noveske’s pinned and set-screwed low profile gas block is included with the barrel (as well as an intermediate length gas tube.)
The Noveske SPR barrel employs an intermediate length gas system which eliminates the short-stroke issues that are sometimes encountered in cold weather with some 18” barrels that utilize a rifle length gas system. The barrel extension has “M4” feed-ramps. The barrel has a 1:7” twist rate and polygonal rifling (not a polygonal bore.)
The chamber found in this barrel is Noveske’s proprietary Noveske Match mod 0 chamber that “was developed to fire MK262 Mod 1 on AUTO in hot environments." I installed the SPR barrel in a Colt M4 upper receiver and free-floated the barrel with a LaRue Tactical 12” handguard.
I conducted an accuracy (technically, precision) evaluation of the Noveske 18” SPR barrel from my bench-rest set-up following my usual protocol. This accuracy evaluation used statistically significant shot-group sizes and every single shot in a fired group was included in the measurements. There was absolutely no use of any group reduction techniques (e.g. fliers, target movement, Butterfly Shots).
The shooting set-up will be described in detail below. As many of the significant variables as was practicable were controlled for. Pictures of shot-groups are posted for documentation.
All shooting was conducted from a concrete bench-rest from a distance of 100 yards (confirmed with a laser rangefinder.) The free-float hand-guard of the rifle rested in a Sinclair Windage Benchrest, while the stock of the rifle rested in a Protektor bunny-ear rear bag. Sighting was accomplished via a Leupold VARI-X III set at 25X magnification and adjusted to be parallax-free at 100 yards. A mirage shade was attached to the objective-bell of the scope. Wind conditions on the shooting range were continuously monitored using a Wind Probe. The set-up was very similar to that pictured below.
For this evaluation, I used one of my standard match-grade hand-loads topped with Sierra 55 grain BlitzKings. When fired from my Krieger barreled AR-15s, this load has produced ½ MOA 10-shot groups at 100 yards.
Three, 10-shot groups were fired in a row from the Noveske SPR barrel from a distance of 100 yards with the resulting extreme spreads:
0.812”
0.732”
0.873”
for an average 10-shot group extreme spread of 0.81”. The three, 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius of the 30-shot composite group was 0.28”
The smallest 10-shot group . . .
The 30-shot composite group . . .
….