Chambering question

[cycbb486]

I want to build my 6Br with a no turn neck at .272. The smith that I talked to told me that his reamer is tight neck, not to worry he could use a throater to get the neck to the .272 that I want. Is this okay or a no no? Could someone elaborate on this process for me.


Calvin

 

[Forum Boss]

Opening up the throat with a throating reamer is not unusual, but it's more difficult to do a perfect job than if the body and throat are cut at the same time. That said, top smiths can pull it off. Also, if you are going to do a little brass prep, a .271" neck might be wide enough. The .272" is just a safer bet with all Lapua lots of brass you might encounter. What smith are you planning to use? We also have a Kiff .272" finishing reamer, .073" freebore, than we might rent you. Brand new, has cut only one barrel. But we'd need to approve your smith.

 

[Changeling]

Moderator, what are the complete specs for you reamer?
Changeling

 

[Forum Boss]

Moderator, what are the complete specs for you reamer? Changeling

Dave Kiff has the print. It was 6mmBR.com .073" Freebore model, 1.5 degree leade, .272" neck, spec'd to shoot 105gr Lapua factory-loaded ammo. With a hand-loaded 105 Scenar, OAL 2.350" I was .015" into the lands with the bottom of the bearing surface about .055" from the neck-shoulder junction. V was 2803 fps fire-forming. Could probably go hotter, but I'd want to bush the firing pin first.

For shooting the 107s exclusively, I might go with a .090 freebore.

 

[Changeling]

Moderator, what are the complete specs for you reamer? Changeling

Dave Kiff has the print. It was 6mmBR.com .073" Freebore model, 1.5 degree leade, .272" neck, spec'd to shoot 105gr Lapua factory-loaded ammo. With a hand-loaded 105 Scenar, OAL 2.350" I was .015" into the lands with the bottom of the bearing surface about .055" from the neck-shoulder junction. V was 2803 fps fire-forming. Could probably go hotter, but I'd want to bush the firing pin first.

For shooting the 107s exclusively, I might go with a .090 freebore.

Moderator, this reamer sounds like a very sound design. For shooting 107's exclusively why would you want to change your throating/freebore from .073 to .090? Do you still feel this way, if so why?
This is the 27' barrel rifle you are currently working with right?
Changeling

 

[Forum Boss]

With 105gr bullets deep-seated,.015"-.020") into the lands there seems to be enough "boiler" room to get good velocity. But if your gun/chamber doesn't like to shoot that way, an .085-.090 Freebore can still get the long bullets .50-60" from the neck shoulder junction which seems a good place to be. That said, a lot of people have had excellent success with the 107s and a .110" or so freebore. But then your little bullets would be hanging out, and you probably couldn't shoot the Berger 95 VLDs which have a very short bearing surface.

 

[Changeling]

Moderator, excelent reply. Can't argue with that logic.

Changeling

 

[Jkob]

If your smith said he could do a different size neck than what is on the reamer with a throater, I would find a new smith. What you do with a throater is lengthen the throat. It will not cut a new neck unles it is a "neck and throat reamer". The reamer makers offer neck reamers, neck and throat reamers and throaters. Be careful of this guy.