30BR freebore length

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eww1350

Guest
I am starting this thread hoping that the 30BR shooters will give input on what freebore length they use...I have had three different 30BR barrels all chambered with a "Robinett" zero freebore reamer....I noticed that Robert Rongero has a 30BR chambered by Jim Borden that has a very long freebore, his bullets are seated into the case no more than .062".:eek:
I can only presume that longer freebore allows more room for powder..I have always wondered how one could get 34.8 grains of H4198 in a case with a "zero" freebore...

All comments welcome...:)

Eddie in Texas
 
eww1350 said:
II have always wondered how one could get 34.8 grains of H4198 in a case with a "zero" freebore...
Click to expand...
It is pretty easy actually it's a compressed load, You can get way over 35 Grains in a 30BR case. Just ask Allie Euber he calls 35.1 his starting point.

Dick
 
My .30 BR reamer is the Robbinett reamer with zero freebore. The reamer is made for the 10 ogive bullets and will work with just about anything else, but you have to seat your bullets deeper. A few years ago I chambered a barrel for Ronnie Cheek for his rail gun so that he could use it for testing his bullets. We wound up lengthening the throat to .060" for what I think was Ronnie's 8 ogive bullets. Lengthening the freebore will give you a little more case capacity. As long as you can still reach the lands, you should be alright. If your throat erodes any at all with .062" of bullet sitting in the top of the neck, you'll probably have a problem reaching the lands. I'd seat the bullet a little deeper and go with a little shorter freebore to allow for some throat erosion. Half way down the neck would be my pick if you want more case capacity.

Lengthening the freebore may not give you any more velocity. Not a benchrest example, but a Weatherby case with a short freebore will get the same velocity with less powder than what it will get with more powder and a longer freebore.
 
It's easy. Trickle it slowly with at least a five inch drop tube. That's what I've used. :)
 
Eddie, my 30BR has a zero freebore but it is a long neck like Jackie's. You use a barrel to fireform the brass rather than using a mandrel to neck it up. When you fireform the brass in a long necked chamber, it comes out at about 1.540 or so rather than 1.520. This gives you a tad more powder room but the real reason for doing it is that you don't have to trim all the brass off the neck to fit the shorter chamber and the brass cvomes out of fireforming real straight. If I remember correctly, the reamer is specd to a length of 1.550.
I ran a 6mm BR reamer into a 6mm barrel and then used a .330 chucking reamer to open up the neck. You can then fireform either using 6mm bullets or you can use the cow method.

Joe
 
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