30BR "No-turn" Chamber Dimensions

[58weasel]

Am going to get a "no turn" reamer for the 30BR.
In looking at some of the possible reamer diagrams, the Robinett style used a "zero leade" approach.
Is this best, or only for tight necks?
Am thinking of shortening the neck length of the chamber to get it closer to the brass neck length; this will give me a good bit of leade with a Berger 115.
Pros & Cons on the leade question would help me in the specs for the reamer.
Thanks in advance for sharing your experience in this matter.

 

[tmwinds]

I could be wrong, but my experience tells me you will have to turn the necks on your brass no matter what reamer you use. When the brass is expanded from 6mm to .308 it leaves a doughnut that has to be turned down.

 

[stool]

but if you blow it out instead of using an expander...ohhhhh
the jackie schmidt reamer has a longer neck and throat...gives more powder volume and seems to work well..i just ordered one.
just make sure you get the neck changed to no turn.

 

[58weasel]

Have expanded the 6mm neck using a K&M expander, and then turned down the neck where maybe half the circumference is shaved and the donut at the neck/shoulder junction is cut down to within a half-thousandth of what the rest of the neck is.

 

[Judd]

My gunsmith's reamer has a .3365 neck...you do not have to turn the donut off the brass, one guy I shoot against with a gun using that reamer doesn't turn his necks. He just expands them and loads them.

Mine, I can't stand the look of the donut and don't mind turning necks so I turned mine just off.

They both shoot real well but we aren't group shooting we are shooting anything from thumbtacks, asprin, poker chips or clays. Mine shoots better than I'm able too and I have a couple times on perfect days shot 200y groups in the .2's but normally they are .5-.75 @ 200y...generally speaking I don't shoot less than 200y...the thumbtacks and asprin are 100y but I have never shot a 100y group.

 

[artbosco]

Am going to get a "no turn" reamer for the 30BR. In looking at some of the possible reamer diagrams, the Robinett style used a "zero leade" approach. Is this best, or only for tight necks? Am thinking of shortening the neck length of the chamber to get it closer to the brass neck length; this will give me a good bit of leade with a Berger 115. Pros & Cons on the leade question would help me in the specs for the reamer.

Call and ask Randy: http://bibullets.com/ Be prepared to only listen once you ask your question, because once you do, you won't be able to get a word in edgewise. Listen carefully, you'll learn a lot.

 

[Shynloco]

I could be wrong, but my experience tells me you will have to turn the necks on your brass no matter what reamer you use. When the brass is expanded from 6mm to .308 it leaves a doughnut that has to be turned down.

I believe that unless you use a longer neck reamer as Judd says, then you must turn the brass and cut off the donut to be able to chamber the brass. But if you had a longer neck reamer, I'd be concerned about the uniformity and concentricity of the casings if you left the donut. Just my thoughts.

Alex

 

[Link]

but if you blow it out instead of using an expander...ohhhhh
the jackie schmidt reamer has a longer neck and throat...gives more powder volume and seems to work well..i just ordered one.
just make sure you get the neck changed to no turn.

Good day

How much of the bullet do you guys like to see in the neck of the brass at a minimum?

thanks

 

[Judd]

There is a donut on the inside you will have to fight if you get it close to the shoulder/neck junction. I would want it above that.

 

[SmokinJoe]

Before I took a break from shooting the 30BR a few years ago, I had Kiff make me a special reamer for blowing out brass. Chambered an old barrel with it, then loaded some new 6BR brass with a case full of bullseye & seated a polyethylene ball on top. When fireformed, this gave me brass with OAL of 1.554, or thereabouts, and the brass was very straight & concentric from the start with reduced doughnut. To me this is the best of all worlds with that cartridge. I think Humble Henry has been doing it that way for awhile, too. Of course, to take full advantage of this you need a chamber reamer with a longer neck (like 1.560). If you are just getting everything together for the first time, all this should not be a problem, and you get the benefit of the experience of several very accomplished 30BR shooters. And yes, you will need to do some neck turning no matter what because of the doughnut. Hope this is helpful. Joe