Steve Donlon
Gold $$ Contributor
I agree with what you said. By turning my necks to .012 my necks are the same as Hornady brass but more consistent. They seem to last okay but not as good as thicker brass. I was looking at Sierra load data and they use Hornady brass for their data. We get more velocity with Hornady brass and accuracy is not an issue for me, but I'm not a bench rest shooter with different expectations. So I will see what happens when pushed with RL16 powder and how long the turned brass lasts.Given identical chamber dimensions, going thinner will work that part of the brass more (it's moving more when it expands and the resized back down).
I've typically turned my necks to .014" and it's worked fine for me, as I've done that to have uniform neck thickness. When I turned some down to .012" thickness, obviously they're going to have to expand more in my chamber when they seal off. Though I anneal after ever firing, I've just not heard of any results of extended use for thinly turned necks used in no-turn chambers.
Certainly, the compressive stress changes with the difference in neck thickness and the particular elasticity for the make up of the brass alloy. A combination of this along with frictional interference all affects how the bullet is being released.
One of the things I found fascinating in the Houston Warehouse Test, when it talked about loading the cartridges where the bullet was loaded long with almost no interference allowing the bullet seating to be set when the pushed into the lands. The cartridges would be loaded long and let the lands push the bullet further into the case. Not what you'd want when feeding from a mag.
I tend to like light "neck tension" as well. Though, if I'm feeding from a mag, the tension I use probably not a good thing. . . especially when I'm loading to a mag length with short bullets.
Yes, I too feel seating depth is really important. . . especially consistent seating depth. And neck tension can be a big factor in getting that.
Though I'm not a bench rest competitor, addressing/eliminating as many factors as I can helps me focus on those things I had less or not control over. Some of them don't make a difference for my skill of shooting, but since I have the time, I do like to remove as many variables as I can.
Hmmm??? you bring up something I hadn't really thought about before. As the pressure in the chamber decreases, when does the neck's springback allow some of those gases to flow back towards the shoulder, if at all?
I don't know how one would identify whether powder deposits were deposited before or after the sealing of the neck???
I can see that for a tight chamber where turning in needed, that .012 would be just fine as long as there's enough clearance. From a metallurgical POV, it wouldn't be any kind of issue, except in some loose factory not turn chambers, the brass would get more of a workout with the cycles of firing and sizing reducing their life spans.