[GWS]

Bart said: It cost me 10 minutes time with each one using a 1/4" wood dowel split at one end with 600 grit emery paper on it passed in and out of the die that was chucked up in a lathe. Any 'smith could do that, I hope.

I have a drill press, but no lathe. Or if the hone Uncle Nick suggests will work then all I need is a padded vice?....would just have to determine the size needed and the target size. So a measurement with calipers on a seated round using that brass, then subtracting .002 should give me the target, right? Then why plug the bore as Uncle Nick suggests. Not being a machinist I don't have expensive tools like pin or small hole transfer gauges, so I wouldn't be able to check the progress so I suppose repeated plugging may be the only way...and that sounds fun. The other thing I would be unsure about is accounting for the brass spring-back factor in the neck. This is where I think I'm over my head, gentlemen, unless I'm over analyzing.

I use the Forster trimmer with their 3-way carbide cutter. I think I understand you....you mean the inner edge at the bottom of the newly cut chamfer. So the easy-out just smooths the new transition to the neck. That's simple enough to try.....ha ha, what's another step at this point.

Except for the small change between steps 4 and 5, there is a very steady logarithmic reduction of improvement with each sizing step, which you would expect because there is less improvement to make with each pass. There is no indication I can see that rotating the case did anything two additional unrotated sizing operations would not be expected to do.

I agree with most of that, except that I felt the non-rotated steps slowed me down because I could get to .001 without them if I just rotated immediately. And less work hardening with the three sizings vs 6 or 7. I reported that in the first thread, quoted below:

A sixth case I simplified. Presized runout was .004" and first sizing was .005. I immediately rotated the case 1/3, sized, rotated 2/3, sized, and measured once. Run-out was .001"

That supports my burnishing theory. You are also burnishing the motor mica into the brass surface, reducing pull on the neck each time. The uneven neck thickness Bart referred to is also going to be a factor. You are probably nudging it a little more to the side with each pass, tending to line it up with the more axial neck position. The same thing happens when you lap a bore irregularity under a heavy-handed dovetail cut. The part of the bore that's out of line with the rest gets rubbed harder by the lap. In this case any part of the brass that isn't on-axis gets more burnishing pressure from the expander, which has the rest of the neck trying to keep it lined up.

That's an interesting theory....and possibly right.

The following about Feamster is interesting indeed!

Feamster did use a rubber O-ring between the lock ring/nut and the press with the sizing dies to let them have a little wiggle room. The Lee lock rings do essentially the same thing if you don't make them dead tight. I've had mixed results experimenting with this and concluded I needed to lap the press and die threads smooth and use a little high pressure lube on them to get the full effect. STP works fine.

Many years ago (close to 40) I read an article in Handloader Magazine, where the writer insisted that one could get better alignment between die and shell holder by loosening the spring that keeps the shell holder. And I've always done that until recently when I made a case kicker for my Rock Chucker and it needed a tighter shellholder to keep it from rotating on me as I fed brass quickly during depriming operations before wet tumbling. I may have to loosen it up some.

Not sure what you are doing with lapping the press and die threads smooth, and why the high pressure lube? How old is your press threads? After 43 years mine are pretty smooth. Well I guess the die is pretty new. I guess I can see that burrs might worsen alignment. I was taught early on to tighten my dies only with pressure on it from the cammed over shellholder to keep the mating die and shellholder surfaces parallel....a loose shellholder would then provide some side to side wiggle room to finish the alignment. So has all that become out of favor now?

I'll have to buy some STP......that's worth a try.....even if it is harder to clean up. As for Imperial....I'm done with that. Only explanation for my experience with that is when the going gets rough, Imperial quits. Who would have thought that super clean and shiny brass would stop it cold.