Questions regarding properly sizing belted cases

[Tidesloe]

How on earth do you attach pics? I've done it before, but cant seem to figure out how to now.

Anyway this rifle is printing paper between 1/4, and 1/2 MOA at 200 yds.
Max group size is 1" at 200 yds. This thing is awesome. Took me a little shooting to get my form and consistency down, but seems to now be consistent in that range. Groups have tightened up, and my flyers aren't happening now. Gonna do a little shooting out at distance this weekend, and see what happens.

At some point I'll have to FL size, and I'll use my Redding body die, and then neck size and see what that gives me.

Nosler brass
215 primers
81 grains Viht. N570
180 Berger VLD's
getting 3150 fps
McWhorter developed load, and it works. We'll see how it does out at long range

 

[TracySes23]

I just purchased my 1st 7 STW. I have laundry list of questions regarding loading for this cartridge. I have some experience loading other beltless cartridges.
I'll apologize in advance if the answers are here but don't have time to study the forum in detail.

Belted cartridges are new to me and as I understand are head spaced off the belt, this would present a different set of challenges for me. To my understanding it seems that with belted cartridges head spacing would also need to be on the shoulder as well for best accuracy. With 2 head spacing points does the belt tend to interfere with proper center bore alignment from shoulder head spacing. Do the belted cartridges require less to no shoulder bump to properly align cartridge with bore upon firing.

My next question is: I have 2 sizer dies for this cartridge. Neither one seems to be able to produce concentric necks. A WAY, I've found to get fairly concentric necks is to rotate 90 degrees part way through, size a little more, rotate 45 degrees, rotate 90, size rest of the way. I've been expanding with Sinclair expander for consistent neck tension. The problem is, my accuracy went away after all the rotations in attempts to get everything strait. Could somebody give me thought on this?

The rifle is a McWhorter custom, which I've not even fired yet. I've had it for a week now, and can't wait to touch some rounds off. I have load data, and ammo loaded by McWhorter that somehow got destroyed during shipping. Hopefully more will arrive tomorrow.
I have plenty of all components to load for it, but the concentricity problems have me concerned. I am considering having a custom sizer die built to alleviate the problems I'm seeing with standard production sizer dies, and hopefully prolong case life in the process.
Any help and suggestions you guy's may have is much appreciated.

That sounds like a excellent idea you have.

There's one thing I've often wondered about concerning concentricity.
I wonder how precise the bore for the ram in a reloading press actually is. I also wonder how square the face of the surface on the ram is where the shell holder goes. Then I think it would be nice to know how precise shell holders actually are. One more thing that should be precise. When the reloading press is tapped 7/8-14 is this thread centered & inline with everything on the ram. All of these things could cause a problem with concentricity. Even if the errors are small, there are a lot of places where accumulated error could be significant enough to adversely affect concentricity of a loaded round. If you consider the sizing die might also have a problem of concentricity between the inside & the outside heads, you have at least 5 places that could contribute to a loaded round being less concentric than we'd like. I forgot one more thing. The nose on the bullet seating screw could also be out.
I'm amazed they come out as close as they do.