Few days ago, after a shooting session, I met two guys boasting that their accuracy was due to working not only the outside of the neck, but the inside as well. One of them, a retired toolmaker, said that to this end he designed and built an adjustable reamer. However, he cautioned me about certain calibers and certain case makes (e.g.RWS) because the neck could be too thin. I agree that working on the neck you assure consistent tension and concentricity between barrel and bullet, however it is curious that nobody (to the best of my knowledge) invented such a reamer before.
Am I ignorant or is it just hot air?

Adjustable reamers are available in suitable sizes for Nitro cases. I am not sure how small they make them, maybe chck at local engineering suppliers.

I have one for reaming necks of thick 500/450 brass. Used in the FL die.

Cheers, Chris

It is all hot air except for some bench rest guns that cal tell accuracy down to a gnat's eyelash. Neck reamers have been around for 100 years and I have done it, with zero improvement in accuracy, in hunting rifles.

Sinclair sells/sold them for popular bench rest calibers.
I've loaded for 30+ years and over 30 cartridges. Never have I reamed the inside of case necks AND never needed to. I do take steps to uniform my brass that others claim is a waste of time, but neck reaming is not one of them.

When I was in high school (early 70's), I formed 22-250 from 308 blanks that I got from the military on training exercises thru the low grounds. Part of that process was to ream the inside of the necks which were thick due to sizing down the brass. I shot all thru high school and college with that brass.

Yes, if you are sizing 308s down, you will need to ream the necks; that is one area where you need to or your ammo won't/might not chamber. Or neck turn will work too.

I have adjustable reamers, if all of them were on one place I believe it would be safe to day I have a drawer full of them. I also had a Sunnen honing machine.

I also have RCBS reamer dies. then there were the old target model dies.

F. Guffey

I think neck reaming or neck turning is not going to be of any good unless the chamber calls for it.

Many thanks. I understand that nech reamimg is close to hot air and that I am ignorant.

I may be wrong, but whaI have understood was that one neck reams or neck turns to fit a custom chamber.

We have built many rifles with tight necks, and usually supply 100 rounds of loaded ammo for them, in cases that have been selected and prepared for that specific chamber.

Usually, with little care, those 100 cases last many years.

One of my favorite wildcats that we dinghies for is the .22-243 Improved.

We have a custom reamer, with tight neck, and the rifles shoot incredibly accurately.

I have built one for a man who lives in Africa, and he uses it to shoot all manner of big game animals.

Inside AND outside neck reaming/turning sounds very redundant. All you are trying to achieve is uniform neck thickness. Never done either - don't have any tight neck or BR guns. The Lee Collet Die gives you nice round/concentric neck I.D.