Driftertank
Member
Sorry, no pics at the moment. Will add later if possible.
So, having finally gotten glass on my AR this spring, I set about working on a handload for it. Rifle is a homebuilt, Aero Precision receivers, Rainier Arms NiB Match BCG, Criterion 16" midlength "hybrid" profile barrel, 1:8 twist, .223 Wylde chamber, supported barrel with Magpul MOE furniture.
Stage 1: Ladder loads.
Brass is once-fired PMC X-Tac Xp193, PSD headstamp.. CCI 400 primers. Hornady 75gr BTHP, COAL 2.255" (2.260 was suggested, but minor meplat variations made me bump it back a hair for the sake of reliability).
Using data from the Western Powders load data .pdf, minimum load was set at 23.0gr, maximum load at 25.8 (NATO PRESSURE SPEC, NOT SAAMI!!). Loads were spaced at approx.2.5gr intervals; 23.0, 23.3, 23.5, 23.8, etc. 10rds were loaded at each interval.
Targets were set at 100yds. I intentionally left the chrony at home, so as to concentrate on group size and watching for pressure signs, rather than chasing velocity. I figure a 2400fps tackdriver beats a 2700fps pattern.
5rd groups were fired, starting at mildest loads, 10 minutes between strings. Primers started to flatten off at 24.3, and 1 pierced primer at 24.8 convinced me that was as hot as I wanted to go. Starting back at mildest loads, I fired another set to eliminate hot/cold barrel bias in groups. In both sets, 23.8gr gave best groups around 1moa, with groups at 23.5 and 24.0 around 1.5
I went home and downloaded all loads over 24.5, reloaded them at 23.8, on an RL650 this time with powder bar throwing charges. All charges sampled threw within .1gr. This powder meters very well.
Stage 2: Velocity data, confirmation, and different rifle test.
Having loaded the rest of the brass I'd prepped in this batch, I went to the range with my chrony, my AR, and my girlfriend's Sig 556.
Given my short barrel and the supposedly mild loading, I was expecting to see around 2400-2500fps. So you can imagine my surprise and delight when my avg. velocities clocked in at 2724, with an SD of 22. 5rd groups started at around moa, getting around 2-2.5moa as the barrel started heating (didnt give the cooldown time this session.)
Given that my girlfriend's rifle has a NATO chamber, skinnier barrel and 1:7 twist, I didnt expect much as I switched over to it. But I was delighted, again to see the cold bore group print right about1", with velocities around 2625.
So this combination seems to have worked out as a brilliantly efficient load for our rifles, giving excellent accuracy (for combat carbines, anyway) and impressive velocity from a pretty stingy powder charge. And I can crank it out rapidly without sacrificing consistency.
Anyone else played with this powder and projectile combination? If so, were your results similar to mine in regards to ideal charge weight and velocity, or did I just get extremely lucky thatboth rifles seem to love this load?
So, having finally gotten glass on my AR this spring, I set about working on a handload for it. Rifle is a homebuilt, Aero Precision receivers, Rainier Arms NiB Match BCG, Criterion 16" midlength "hybrid" profile barrel, 1:8 twist, .223 Wylde chamber, supported barrel with Magpul MOE furniture.
Stage 1: Ladder loads.
Brass is once-fired PMC X-Tac Xp193, PSD headstamp.. CCI 400 primers. Hornady 75gr BTHP, COAL 2.255" (2.260 was suggested, but minor meplat variations made me bump it back a hair for the sake of reliability).
Using data from the Western Powders load data .pdf, minimum load was set at 23.0gr, maximum load at 25.8 (NATO PRESSURE SPEC, NOT SAAMI!!). Loads were spaced at approx.2.5gr intervals; 23.0, 23.3, 23.5, 23.8, etc. 10rds were loaded at each interval.
Targets were set at 100yds. I intentionally left the chrony at home, so as to concentrate on group size and watching for pressure signs, rather than chasing velocity. I figure a 2400fps tackdriver beats a 2700fps pattern.
5rd groups were fired, starting at mildest loads, 10 minutes between strings. Primers started to flatten off at 24.3, and 1 pierced primer at 24.8 convinced me that was as hot as I wanted to go. Starting back at mildest loads, I fired another set to eliminate hot/cold barrel bias in groups. In both sets, 23.8gr gave best groups around 1moa, with groups at 23.5 and 24.0 around 1.5
I went home and downloaded all loads over 24.5, reloaded them at 23.8, on an RL650 this time with powder bar throwing charges. All charges sampled threw within .1gr. This powder meters very well.
Stage 2: Velocity data, confirmation, and different rifle test.
Having loaded the rest of the brass I'd prepped in this batch, I went to the range with my chrony, my AR, and my girlfriend's Sig 556.
Given my short barrel and the supposedly mild loading, I was expecting to see around 2400-2500fps. So you can imagine my surprise and delight when my avg. velocities clocked in at 2724, with an SD of 22. 5rd groups started at around moa, getting around 2-2.5moa as the barrel started heating (didnt give the cooldown time this session.)
Given that my girlfriend's rifle has a NATO chamber, skinnier barrel and 1:7 twist, I didnt expect much as I switched over to it. But I was delighted, again to see the cold bore group print right about1", with velocities around 2625.
So this combination seems to have worked out as a brilliantly efficient load for our rifles, giving excellent accuracy (for combat carbines, anyway) and impressive velocity from a pretty stingy powder charge. And I can crank it out rapidly without sacrificing consistency.
Anyone else played with this powder and projectile combination? If so, were your results similar to mine in regards to ideal charge weight and velocity, or did I just get extremely lucky thatboth rifles seem to love this load?
