Simple Tool Fixes the O.A.L measurement issue.

[Texas10]

I just completed my first build, a 6mm BR assembled entirely from parts I bought on this site and began the loading process. In trying to find a seating depth for my 105 BTHP Match, I could not get a consistent reading on my Hornaday OAL tool. The difference in OAL measurements from a light tap to a firmer push was .142, an impossible spread to work with.

I thought about what I was trying to do, and then came up with a simple idea. I took one of my fire formed and FL sized Norma cases and drilled and tapped the head for a 6-32 thread, and then seated a bullet long.

Using an old 3 piece cleaning rod, I screwed a section into the back of the case and inserted it into the chamber. I could quite easily feel the bullet stick into the lands. I removed it, seated the bullet deeper using my RCBS micrometer seating die, and repeated the process.

When I had it down to about 2-3 thou in the lands, I inserted a cleaning rod down the muzzle and using both hands, could shuttle the bullet back and forth into and back out of the lands. It was quite easy to feel when I was engaging the lands. A couple of more trips into the seating die and I had a perfect measurement to touching the lands, but that was with a 105 A-Max.

When I again tried the BTHP I found it was a slightly fatter bullet, and would drag in throat before hitting the lands. But using this method, I still could seat to touch by shuttling it back and forth.

Anyone need a Hornaday OAL gage? I got a spare one now

[rbp75503]

I have both Hornady and Sinclair tools. Different methods but will get you there in the end.

http://www.sinclairintl.com/reloadin...prod35491.aspx

[RC20]

Mine is simpler.

Use the Hornady to get ball park.

Use a blank cartridge, seat a bullet long. Close the bolt slowly. If it sticks before turn down, reduce length until it goes turn down.

If it sticks (either before turn down or after) tap the bolt handle with a plastic screw drive handle or piece of wood.

Once it either quits sticking of you see just a shade of distortion on the bullet Ogive, that is your max COAL.

Measure it with the Ogive tool and that's your initial data point (it will grow ad the bore erodes)

If you are jam it in the lands then you know if you make it .005 longer it will jam in the lands. Maybe .010 (with bolt turn down)

If not, you can reduce it .005 ad a time until you have the best accuracy.