So, if the inside of your case neck is not concentric, a reamer will not improve this condition? Does this mean most neck thickness concerns are with the outside dimension, not the inside? Would you need some kind of lathe to accurately true up the inside of a neck that was not concentric?"..a single tool (cartridge-specific?) that will turn the outside of the neck and ream the inside of the neck, all in one operation?"
No such tool exists. And, really, it need not exist.
Reaming (alone) does nothing but enlarge the neck inside diameter, if it is thick but inconsistant it will become thinner and inconsistant.
A turner works the necks between a central mandrel and the cutter so the necks become both thinner and consistant; a much better deal.
Outside neck reaming will take care of concentric problems and neck thickness due to brass migration. After outside neck reaming it may not be aligned, but after you fire form it, it will straighten out and be as perfect as your chamber is. The only thing that inside neck reaming will do is smooth out any rough spots, this can be done with polishing with something like steel wool on a brush. After the outside neck turned case is fired, if your chamber is good, your neck should be perfectly concentric and thickness should be consistent. If you can perfectly size that case/neck, you will have a perfectly concentric/square neck.Perhaps I'm wrong, but I always thought the reason for neck turning was not about concentricity, but more about getting rid of the excess brass that migrates toward the case neck. You don't want an overly thick case neck putting a death grip on your bullet when the cartridge is chambered. If concentricity was the end goal I think you would ream the inside of the neck and then turn the outside of the neck. I believe the people that shoot at such extreme ranges that every little bit is required do this. Perhaps I'm wrong about that, but I still want that die Broom dreamed up.
I'm having a hard time envisioning that...does it ream and outside turn, at the same time, or just ream?Yes I have, not in the way you have described but the very high end of sizing and inside neck reaming has been available from RCBS for years, expensive but precision, the combination is a full length sizer die that uses a reamer centered in the top of the die, size the case, insert the reamer, ream the inside of the neck, the neck is in the absolute center of the neck supported by the die. I have one in 243.
Mike, thanks for putting that in a way that finally makes sense to me...just another example of me trying to make things too complicated.No need for such a contraption (with both inside and outside cutters). Since the brass is easily formed (relative to other metals), push a mandrel into the case mouth. Inside diameter is now exactly the size of the mandrel.
Cut off excess on the outside with the neck turner.
Or, alternatively, push the case into a die where the outside of the neck is sized down exactly, and run a supported reamer in (per the Lee Target Model Loader).
The reason such a contraption doesn't exist, is there are at least to better and cheaper solutions on the market......
I'm not sure if that would have any benefits.Mike, thanks for putting that in a way that finally makes sense to me...just another example of me trying to make things too complicated.
Now, what about the idea of a single tool, with precise neck dimensions, that the neck of a case could be slid into immediately after being heated to the proper temperature for annealing? Would there be any value in such a process? In other words, would inserting the case into a perfect die while it is warm, shape it perfectly and then hold that shape, when it is quenched?
Would there be any logic in something like a standard die actually having a low-voltage current running through it that first shapes the neck, then quickly heats it to proper annealing temperature in a set, timed operation? One of the challenges of annealing is to get only the neck heated up, to the right temperature. Maybe a tool like this would shape the neck properly and then relieve the stress on the metal, created by working it, all in one step?