Which Reamer?

[Roeder]

Please help me understand why a reamer would be cut that leaves the body part of the chamber too tight. On the 6mmbr.com page for the 6BR, the body runs from .4709 at its fattest point (bottom) to .4598 right before the neck. Judging from that, it does appear the chamber would be too tight at that point. That is worrisome. Understood on the Lapua brass vs Remington brass and the longer dimension of 1.570 for the Lapua brass.

I don't understand the need for sending in a dummy round. I really have no idea where I want the bullet seated in the case.

It appears I really need to settle on proper bullets. Given this barrel will be used 85% at 100 yards, I probably should be using very light bullets. From additional reading, it seems like 55 - 75 grain may be ideal, lighter than the 70 - 90 I mentioned originally. ??? If so, then maybe the zero freebore reamer (first one) is the right one, but am perplexed by the tight body dimension.

Thoughts and opinions welcome.

Phil

These are older prints, from the time before Lapua started making 6BR Brass. The older Remington brass ran smaller, and many gunsmiths designed reamers to match, so that the cases fit the chamber better. The Lapua brass tends to run a little larger and tends to run into problems when used in a minimum spec chamber. This also holds true for some, but not all other cases. In particular the 6.5-284. Many shooters found that the new Lapua cases were so much larger than the old Winchester that they would not even chamber in some rifles.

As far as the seating depth goes, you want the base or bearing surface (If boat tail) to be above the bottom of the neck because the donut forms there. You would seat the longest bullet in a empty case so that the largest diameter of the base of the bullet is about .05 above the junction of the shoulder and the neck and sent that in to your reamer grinder.

The long neck of the BR case allows a lot of flexibility in bullet weights and zero freebore will work with most bullets up to 70 grains and still allow plenty of grip on the shortest 55 grainers. .040 to .060 works very well with most 62 - 70 grainer, especially flat base benchrest bullets, but can be a little long if you want to shoot 55 grain Ballistic tips or 58 grain V-Maxs