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Old February 15, 2014, 04:30 PM   #1
UlicniTrkac
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Bullet runout

Hello
I get some strange readings with my 8mm Mauser reloads.

Neck size after the round has been fired is 0.359. What neck wall thickness should I go after (I use Sierra 200 gn HPBT Match .323)?

I did turn down neck size with RCBS hand neck turner. After them being both full length (with LEE die) or neck sized (with CH4D die, and 0.343 bushing), I get readings at max 0.003 run out (on the outer side). Inwards should be the same (because neck thickness is quite uniform - measured).
After seating the bullet, I get the same readings on the neck, but on the bullet I get the 0.01 run out (I can spot it with my eyes). I am using RCBS competition seater die, which is a bit excessive?
And I have a LEE Reloader Press (I know, I'm cheap )

What can I do to improve that? Maybe I over thinned the neck wall? Or am I doing something wrong?
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Old February 15, 2014, 05:09 PM   #2
chris in va
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Are you entering a competition? Sounds like a lot of work for your average range trip.
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Old February 15, 2014, 05:28 PM   #3
Sierra280
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It's great your checking bullet (or really neck) concentricity.

What kind of brass are you using? It may not be anything you are doing, I've run into cheap brass (never loaded 8mm though) that did not have the case necks very well aligned with the case center axis, competition seating dies do nothing to help this, competition full length resizing dies can many times help remedy this, but most of the time I toss those in the 'reloadable for fouling/plinking' pile.

Edit--this is something I mention in my reloading record keeping book, hasn't everyone bought a copy yet?
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Old February 15, 2014, 05:34 PM   #4
Jimro
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Check the body of the cartridge. If the bolt face isn't true against the chamber, brass can stretch into a "banana" shape on firing. This will show up as runout as the neck and bullet are not aligned with the lengthwise axis anymore, even after resizing.

If that is the case, which it may not be, but seems likely, figure out where the bend in your brass is, then mark the base of your cases with an index mark. Load them with the index mark in the same position for each shot for max accuracy.

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Old February 15, 2014, 07:15 PM   #5
UlicniTrkac
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No banana bending
but what I did find out is that RCBS seating die is all but competition. Its only there to seat the bullet to desired length, not to seat it concentrically.

The other problem I figured is the bushing size of the CH4D neck sizing die - .343.
I go from 0.359 to 0.343 directly, and what I have read max sizing shouldnt be more than 0.008. So I need another bushing, and to trim my brass to 0.010 instead of now measuring 0.013. Or to get a .347 and lets say 0.353.
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Old February 16, 2014, 11:23 AM   #6
UlicniTrkac
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Just got back from the range
I have fired 50 shots of this bad run out 8mm mauser bullets.
At 500 meters prone I got consistant 20cm 5 shot groups.
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Old February 16, 2014, 01:24 PM   #7
Jimro
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That works out to a consistent 1.4 MOA load by my math.

That meets the WWII Wehrmacht sniper standards for a K98 last I checked.

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Old February 16, 2014, 02:15 PM   #8
UlicniTrkac
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Just to add, I wasnt shooting them from my rifle, and thise rounds were made for her specs, but this is a good result in my book
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