Neck Measurement(s) Questions

[Gargoyle]

Some use mandrel and some don't. Long story and you can do a search on here but you don't have to use a mandrel at all. Are your dies bushing dies? You can control neck tension with the bushing without any mandrel or rod touching the neck. Been done for ages that way.

Don't they form donuts?

 

[JFrank]

What is optimal clearance between loaded round and ID of chamber neck?

For me it’s about .003 but depending on the bullets pressure ring it could vary slightly.

 

[JFrank]

Don't they form donuts?

mine don’t

 

[Bc'z]

Don't they form donuts?

Bushings only size the 1st 2/3-3/4 of the neck leaving the section of neck that may have a doughnut unsized.

 

[gunsandgunsmithing]

Bushings only size the 1st 2/3-3/4 of the neck leaving the section of neck that may have a doughnut unsized.

Yessir and I don't think donuts hurt a thing if the bullet isn't seated into it.

Don't they form donuts?

More than anything else, without splitting hairs, donuts are most common when brass is necked up because the brass in the shoulder is generally thicker than the brass in the neck. When you neck a case up, the neck obviously is a bigger diameter. That brass come from the thicker shoulder brass to form the larger neck. Yes, brass flows forward some as well and can form a slight donut but a lot of that is within our control by sizing minimally, creating less brass flow. Just keep the bullet out of the donut area and forget about it. And as Bc'z said, a bushing typically doesn't go that far down the neck. Again, some of that is within out control and some of it is that the design of most bushing dies won't let the bushing go that far down the neck anyway. So, there's this portion at the bottom of the neck that never gets sized and therefore the donut doesn't get pushed inside. Instead, you get a little bulge on the outside of the neck that very closely fits the chamber. Some feel that helps case alignment. Hard to argue with that. Donuts get more attention than they deserve.