Donut Newbee

[Lapua40X]

I've been loading 6BR for a while but always with relatively light weight varmint bullets. I'm currently working on loads for the 107 grain Speer HPBT and that means seating the bullet much deeper. I develop a "donut" fairly early (at about 3 firings) which interferes with the bullet seating depth when I want to establish a bit of a jump ahead of the lands. Neck reaming is a new experience and with the amount of brass that I'm collecting with each pass of the reamer to eliminate the donut, not to mention the brass resulting from trimming neck sizes for tension etc., I'm wondering how long I can expect this Lapua brass to hold out. Anyone with experience here that might have some advice?

 

[TimP]

You only want to remove the doughnut your reamer should not mark the inside of you case neck. What I do is measure the doughnut and the inside of the neck with a pin gauge. I will then order a custom sized reamer to remove the doughnut but not touch the inside of the neck from L.E. Wilson to use in their case trimmer.

 

[fdshuster]

Lapua40X: Another solution to the problem of donuts is to have the proper freebore length on the chambering reamer so your bullets of choice can be seated where you want them, without contacting the donuts. Then you can forget about having to remove them.

One of my 6BR PTG reamers has .050" freebore, the 107 SMK's and the 105 Berger #24428 can be seated to touch ( my first choice of seating depth), without making contact with the donut. The full .243" diameter of the bullets are anywhere from .010" to .020" in front of the donut. Another bullet is the 108 Berger #24431, but when the chamber is new the bullet will contact the donut, so I use that bullet with my longer throated chambers until the "short" one grows longer from erosion. The 108's are used in my .080" and .104" freebore chambers only until then.

For what you want to do, a freebore length of .075" would work fine, giving you some jump, but still clearing the donut.

Best thing to do would be to contact Dave Kiff, tell him what you want to do, and he will recommend the proper freebore length.

 

[LCazador]

Are you neck turning ? If you are , make sure you're cutting into the shoulder at least a 32nd of an inch . Also make sure you're not pushing the shoulder back with your sizing die more than a thousandth . You've got some serious brass flow going on . Ditto on the post that says to order a custom reamer from Wilson , if you have to cut the donut out . K&M also makes a donut cutter .