Donuts, will they always hinder accuracy?

djfergus

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Im shooting 6.5 saum prime ammo. When I try to slip a 147 eld into the fired & unsized case, the bullet stops at the neck shoulder junction. So I know I have donuts. I'm not accustomed to having donuts or maybe I just never knew I had donuts with other cartridges. My question is: will donuts always keep a rifle/ load from shooting good when you will be seating the boat tail junction below the neck/shoulder junction?
 

djfergus

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Im shooting 6.5 saum prime ammo. When I try to slip a 147 eld into the fired & unsized case, the bullet stops at the neck shoulder junction. So I know I have donuts. I'm not accustomed to having donuts or maybe I just never knew I had donuts with other cartridges. My question is: will donuts always keep a rifle/ load from shooting good when you will be seating the boat tail junction below the neck/shoulder junction?
Well, I guess I'm sort of answering my own question, but I know if the donut causes excessive runout on the loaded round, accuracy will be degraded. So I guess the next question is: does donuts always exhibit unacceptable runout if the donut is not dealt with? I don't have the dies I'm going to be using yet.
 

Mikecr

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Donuts do not contribute to runout.
Seating through donut area is undesirable due to extreme tension/tension variances, and possibly causing interference with chamber neck(unsafe).

But donut area is rarely a problem, in that most people do not seat bullet bearing into it.
 

djfergus

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Donuts do not contribute to runout.
Seating through donut area is undesirable due to extreme tension/tension variances, and possibly causing interference with chamber neck(unsafe).

But donut area is rarely a problem, in that most people do not seat bullet bearing into it.
I ran a .261" diameter mandrel into the cases and it passed the donut with room to spare but a 147 eld is still stopped at the boat tail junction when running it in by hand on a fired unsized case. If I run 147s, I will have to seat them below the junction due to the .081 freebore. I may just give the cases a try as is after I get my dies
 

djfergus

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if your donuts are less in diameter than your neck clearance .. pre-expand with and expander mandrel, seat bullet and check if you have enough clearance
I see what you're saying. It makes good sense. Right now, the donut has an opening that's greater than .261 but smaller than .263, so say it's .262. I've got Lee making a Collet die and the mandrel should end up @ .261. Assuming .001" spring back, the Collet die should leave the sized neck at about .262" The donut may not be quite as much of an issue as I thought but I will see. If that doesn't work, I will take your advice and pre expand with a .263 or larger mandrel & partial neck size above the donut area if need be. If the donut it still there, I think I will be able to feel it in seating the bullet.
 

Bob Wright

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I ended up buying a K&M neck turning kit. My groups were going from great to horrible in .2 grain increments of powder charge. Pressure problems started destroying brass. Bullet seating was ok until the boat tail came in contact, getting progressively worse the next time I reloaded.
I'd say you need to invest in a reaming mandrel/ neck turning equipment. I wasn't getting any groups during load development.
My final variation in ES ended up at 3100 fps +/- 2. Significant improvement.
 

codyadams

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They can be pretty distracting, I really like the cream cheese maple bars personally, and if there are a couple of them there, I have a hard time focusing, especially since that usually means I need coffee too, and then I just get jittery, and accuracy generally goes out the window......
VZM.IMG_20161007_091351.jpg
 

codyadams

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😂. I've got to have some of those cream cheese maple bars.
Well, you will have to make a trip to Benedicts in Mountain View Wyoming for them, but get there before 10 am or so, otherwise they are sold out!! Ha ha.

Sorry to derail your thread, with all the crazy going on, gotta throw in some lightness ha ha.
 

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