Neck Sizing Vs. Full Length Sizing and Neck Tension

Veteran

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The tip on Alex Wheeler led me to this site below. There are 4-5 other follow on articles referenced in it.
His video was evidently removed from You tube and I did not find it on his site either, except the portion about bolt
closing tests with the bumped cases. But it did not show the detail on how to bump that these articles do.

 

Veteran

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Sorry for the misleading info. The video is for finding the lands with a seayhed bullet.
No, the Alex Wheeler tip led me to a great set of articles. The video is removed from youtube. Thank You.

 

Wedgy

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No, the Alex Wheeler tip led me to a great set of articles. The video is removed from youtube. Thank You.

He deleted his youtube account and put the videos on his site;

 

wasskeet

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Here is video clip from Jeff Brozovich of LRO on bumping the shoulder.

 

Mike Matteson

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That interesting to me. I shoot a lot of belted magnums rifles. In my 308 Norma Mag chamber I use a 300WM neck sizing die. The necks are shorter than the 308 NM cases. It only resize the about half the neck. No bumping was done. I normally use 300 WM Brass to start with. It's a hell of lot cheaper than trying to get 308 NM brass. F.L. size, and fire form and you are off. I know it extended the length time I could use the brass. To the point I was loosing the brass to primer pocket getting to big to retain the primer properly. Now I have learn a new way to extend that to get additional firing from the brass. I haven't put that into play just yet, but I will try it to see how it works out.
 

nksmfamjp

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However, in my own experience, I haven't so much run the tests to match up one method against another, its just that I learned the hard way you CANNOT full length size belted magnum cartridges past 2-3 times without head case failures. At least I could not. I had 6-7 head case failures on my .300 win mag. which of course is a belted magnum.
I get that I’m overly focused on just this one point. A magnum is headspaced belt to bolt face, so the firing pin/ejector doesn’t push it forward until the shoulder touches, usually. In a normal headspace gun, the belt should touch first with new ammo.

Upon firing, the case expands forward mostly to meet the chamber and of course and head clearance allows minimal rearward expansion.

Without annealing, I would expect neck and shoulder cracking as a failure from all the work hardening.

Since your cases fail by head separation, I’m thinking your headspace is NG. Have you gage’d it? I say that because the case would get pushed forward, fire, expand, then the head area(due to excessive head clearance) is expanding back to the bolt face excessively, over working the head.

Anybody else see case head failures on magnums as common?
 

Just ken

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Question, does a round sitting in the chamber loose align the bullet with the barrel better than round pressed up against the shoulder?
On the loose side, error is the chamber diameter at neck vs. round neck diameter. Bullet will be low by the difference between the 2.
On the pressed up against the shoulder, error is the accuracy of shoulder vs. chamber. Impacts are concentricity and die vs. chamber differences.
 

Veteran

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I would guess

1) Depends on the specific rifle chamber and specific ammo and specific sizing methods
2) Is the ammo neck turned to help concentricity
3) Bullet jump setting
4) Head spacing and belted vs. non belted cartridges.
5) Luck......
 

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