Doing load work-up for a Tikka .223 Ranch with 16" standard lite contour barrel. Using 77 TMK and CCI 400 Primers.
Initially tried TAC and CFE 223 which I had on hand. TAC gave best veloicty at 2670, would get split groups with 80% being in a nice tight cluster and the other 20% as fliers 0.5-1" from the main group. CFE 223 produced good groups but I could not get good velocity out of it. 2580 with book max loads and it is quite temp sensitive.
This last weekend picked up n540 which on initial testing is awesome stuff. Great accuracy and the by far the most consistent velocity (low SD). Load is 23.8 n540 with 77 TMK seated to 2.32 in Starline Brass. Produced multiple groups like the one below. Not sure what the temp stability of this powder is but it has to be better than CFE 223.
Also tried Benchmark which is a bit fast but I had on the shelf and it did well too accuracy wise. 0.9" for ten shots with 2595 fps.
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