So I went to the range today. Yeah, I'm a fool. It was 22 degrees and windy. It was crazy cold. My hands were hurting after about ten minutes of exposure. Fortunately, it didn't take too much longer than that for me to chrono and group my new test .223 rounds in my SIG 556.
I only shot about 25 test rounds. They all cycled and went bang, even the 5 or so that had questionable case gauge results. Cool. I'll take that. Groups were okay. About 1/2 inch at 25 yards. I didn't have access to anything longer than that today.
They chrono-ed at about 2700 fps. I think that's about right for a 16 inch barrel. All my reloading manuals say 26grs of W748 should yield about 2900 for a 55gr bullet at an OAL of 2.215. But they are all using a 24-inch barrel for the tests. So I think I'm just about right. Besides my factory 55gr ammo crono-ed at about 2800 the other day. I'm not too far from that. My load is 25.8gr of W748 under a Hornady 55gr FMJBT bullet with an OAL = 2.215. I my up the powder load a grain or two.
The next batch of bullets I buy, however, will be 62gr. My rifling has a 1-7 twist. That's a bit fast for a smaller 55gr bullet. I notice that the 62gr factory ammo groups a little better for me.