Donut formation

[wboggs]

Is it necessary to seat the boattail shank junction up far enough to clear the neck shoulder junction to avoid donut formation? Thanks
Bill

 

[DocBII]

Bill,

Donuts will happen unless you either ream or neck turn the case to prevent them. They may even come back as the case stretches.

You can prevent a pressure spike from a donut by making sure the base or boattail is above donut portion of the neck/shoulder junction. If the boattail/shank of the bullet will be below the neck/shoulder junction of the case, consider neck turning or reaming the case.

HTH,
DocBII

 

[Dave Brown]

Yes, it would be smart to do so.

 

[BoydAllen]

Doughnuts are not formed because of where bullets are seated, but they can cause problems if bullets are seated to touch them.

 

[gunsandgunsmithing]

JMHO here, but here goes..In my experience, the single largest benefit of a tight neck chamber is brass life. If you run more neck clearance, as in enough for the doughnut to form on the outside instead of the inside, along with using a bushing die or similar, to allow you to NOT size the doughnut back into the neck..it won't contact the bullet. The doughnut on the outside will only help align the case in the chamber.
This will allow the bullet to be seated below the neck shoulder junction without any issue except using up powder capacity. If choosing between being able to load accurate ammo at mag length...or not, I must say, I don't see a significant reason why more people don't set up for this.


The needed clearance can be attained by neck turning, a larger neck chamber, or a combination of both. Let the doughnut happen...just don't let the bullet come in contact with it and I think you're fine. Yes, this is against conventional wisdom, but what else is new? LOL!