30 BR cast bullet optimum freebore

[Spook]

Looking to begin shooting in local cast matches and my 30 BR is shooting patterns as opposed to groups.
My thought is , it being a 15 twist, to use "light for caliber" bullets.
Does anyone have an ideal freebore dimension before I chuck it up and have at it?
I appreciate any help.

 

[JSH]

You might have some more in put at the cast bullet association site. A lot of knowledge there.

 

[charlie b]

Yep, I'd look over at that forum as well. I shot a lot of .308 cast, but, a 1-10 twist so I was usually shooting heavier bullets slower.

If you want a shorter bullet I'd look at the RCBS 165SIL or the NOE 310-165-FN H3 (XCB). They should work with a 15 twist. There are some others that might also work. Look at the Cast Bullet Assn website for past match results. A lot of folks run the .30BR and show their equipment and loads.

Before I had to stop casting a .30BR was my next pick for a barrel.

 

[charlie b]

Went back and ran the JBM stability calculator.

The 165gn XCB bullet (which is 0.965" long) at 2000fps the stability is 1.9 for a 15 twist. Even at 1700fps it is a 1.8. Which means it is very stable with the 15 twist.

The 210 bullet (Eagan design) I used shows a 1.3 at 1700 and a 1.4 at 2300fps, so a bit on the ragged edge.

 

[WayneShaw]

The throat in your barrel could be a big problem. Most 30 cal bullets are sized either .309 or .310, and most 30BR reamers don't have a freebore at all. Throating with the proper leade will let the bullet be seated properly and enter the barrel without deformation.

 

[charlie b]

IIRC, the RCBS 165SIL is a full bore rider so could be loaded with a zero freebore. The 165XCB needs a bit more than a std .308 freebore since it is a tapered design.

 

[Alex Wheeler]

I ordered a .310 diameter throater for doing cast. Theres a 195 bore rider desighn from rcbs that shoots so good in my 1903 I always wanted to do a 30br to see what it really can do.

 

[DShortt]

I don't know if you've been casting you own or if so how long you've been at it. I can tell you having the most consistent bullets possible, including diameter, weight, length, complete fill-out and flat bases is going to be critical if you want the best accuracy possible.
You might be surprised at what you find if and when you carefully examine commercially available cast bullets as well.

I apologize if you are already well aware of this. I just don't know what your experience level is.

Edit to add - I can also tell you many of the posters on a large forum dealing exclusively with cast shoot primarily at 50 yards. It's not the forum mentioned in post #2.