Some of the same guys are weighing charges to the nearest 1/10 of a gnat's ass and have no idea if their cartridges are straight.
I’ve tested concentricity a bunch. It’s necessity is a bit over blown. Within reason.
I agree. I started chasing concentricity in my loads several years ago and never realized gains in accuracy.
Good, consistent neck tension yields better results IMO.
Again, would like to hear about your tests.
I've described just some of mine, but have many other examples.
Would agree that consistent neck tension is part of it, partly because that usually implies consistent neck thickness and sizing--which usually results in more consistent bullet alignment.
Not trying to start an argument, but in my limited testing the gains in accuracy I've seen have been due to consistent neck tension.
I bought a Remington 308 5R a few years ago and bought 200 rounds of Lapua 167 gr match ammo with it to have the great brass for reloading. The match ammo was 1/2 MOA or better, fantastic stuff. 10 shot groups with no flyers into a ragged hole without really trying. So I started testing loads with this brass and was getting my best results with Hornady 168 gr AMAX bullets but not quite a good as the Lapua. My reloads were sized with a Forster FL sizing die and my bullet runout was consistently.0015 -.003 seated with a Forster Micrometers die.
I decided to measure bullet runout on some of the Lapua match ammo and to my surprise it was .003 to .006. I decided to buy a Redding bushing neck sizer die to see if results improved. I used a .336 bushing and sized about 2/3 of the neck. Concentricity also improved to consistently under .0015 bullet runout.
The results were improved accuracy without flyers for this gun. I've bought a few more of Reddings FL bushing dies for some of my other guns and have also seen some improvement in the little amount of shooting I've had time for in the last couple of years.
Certainly not a scientific analysis, but my limited results show that sizing brass for consistent neck tension will yield better accuracy. Yes, concentricity also improves when sizing with bushing dies set up properly, but I was already getting concentricity of .004 or less using standard FL sizing dies.
I would never try to compare my shooting experience with yours, and one reason I tried the bushing die was from watching your reloading video. It's just my opinion from my comparatively limited experience that good consistent neck tension will improve accuracy, and better concentricity is a byproduct of better neck tension, not the primary cause for improved accuracy.
