Carbon donut

Get or give advice on equipment, reloading and other technical issues.

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Joined: Sat Nov 29, 2014 11:15 pm
Location: Adelaide SA "PTRC"

Re: Carbon donut

#16 Postby Jase PTRC » Mon Oct 23, 2017 6:29 am

I had this trouble when i started a new batch of bergers when i first started reloading, it turned out that the newer batch of projectiles were substantially longer base to ogive than the previous. Even though i was measuring with a comparator to the same length as my previous lot. I also realised my Hornady Comparator was also measuring further up towards the tip of the projectile than where the actual ogive was. After having this issue i went back and got my modified case out and re checked this new batch i ended with a measurement that was .030 different to the previous batch causing me to go from .010 jump to .020 jam. So the actual shape of the ogive was considerably different and caused me the problem. Needless to say i now check every new batch in with the modified case.

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Joined: Thu Oct 20, 2005 12:46 am
Location: Cowra NSW

Re: Carbon donut

#17 Postby KHGS » Mon Oct 23, 2017 7:39 am

Gyro wrote:

Have we identified what carbon and where yet lads ??

Mr Boyer's book talks about a carbon ring at the front of the chamber that can be a problem. This build up ( assuming it does exist ) will only be removed properly with a special tool used in a certain way ?

The post at the link above explains the carbon ring formation exactly. SAMI spec reamers USUALLY cut the neck up to .030" longer than trim length & this is where the carbon ring forms.
Keith H.

Frank Green
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Joined: Wed May 28, 2014 11:48 pm

Re: Carbon donut

#18 Postby Frank Green » Sat Oct 28, 2017 1:24 am

I'm going to say no to the carbon ring causing the problem. 2208 is Varget correct? It's all I run in my .308 win. guns with no issues as well as some other calibers.

I'd like ya to find out the exact chamber reamer used. Get a print or drawing of the chamber reamer if you can. The first thing that goes on a chamber reamer is the throat as this is cutting all the time even if you use a roughing reamer. When it goes it will start cutting undersize. You could have one problem making another problem appear etc...

I'm curious.

Later, Frank
Bartlein Barrels

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