Starting this year the highpower director decided to build 6 AR uppers dedicated to shooting Infantry Trophy only. That will take the heat off individual rifles. I zeroed the first four today.
I put up a target at 50 yards if I needed it but really started at 100. They all were on paper using mechanical zero. When I had all four uppers (switching out over a Rock River lower) shooting point-of-aim-point-of-impact at 100 yards. (that's hitting at the top edge of the front sight blade) I switched lowers, (making sure they work with multiple lowers), to an old Colt, went up 20 1/4 minute clicks and shot them at a 200 yard bullseye target center looking for X-ring hits. I shot three-round strings out of the magazine to check function.
Everything off a bench with a rest. Checked the results with a Kowa but had to walk downrange to see groups and patch holes at 200. Sunlight, but shooting into a shadowed target. Shot at least two three-round strings with each upper so...lotta walking. (eight round trips to 200, plus setup and takedown, plus more)
I had a bay of the East Texas Rifle and Pistol club to myself for most of the time, until Alan showed up, then another guy.
Most of the "feel" in an AR is in the lower, where you touch it, so they all felt the same. The barrels are floated and left nearly full barrel blank diameter under the sleeve. Nice and heavy.
With the 200 yard zero Rick Crawford will run the front posts down, (five minutes a revolution), to take out the elevation and use a caliper-dial gauge he has to move the front sight bases over to put the windage near zero. Most of the uppers were U 32, L 14, ( or something like that) so there is some adjustment to be made. We want to end up about U 5, R 1 or so at 300 yards. Closer to mechanical zero.
Used the team IT load: bare 77 Sierras over 25 grains of Varget in a LC case with a CCI 450 magnum primer.
Upper number 4 wouldn't eject. (extracted, but stovepiped) I switched bolts with #1 and it worked fine. Problem in that bolt. Probably ejector.
Alan and I shot his Les Baer Service Pistol .45 in a Ransom rest and I shot it one-handed at 25. We also had to partialy unf##k a guy who was shooting an AR A1 kit gun that he had made. Flat top with triangular handguards, standard bad trigger, no float kit, bad halo sight, mishmash of ammo. There aren't many guns that don't deserve love but that one probably needs...tough love.
Fun being out with new rifles to play with. Even jogged to the 200 yardline and back a few times in the heat.