6mmbr neck sizing bushing size

[Hanic]

Greetings all,

I am taking the plunge into 6mm BR. I have a Pac Nor barrel on order to be chambered to Lapua case size specs with a no turn neck,which I assume is 0.272). Also just received a set of Redding Competition dies without any neck sizing bushing. My question is what size,s) do I want to use for this set up? This answer plus any other info that can help a newbie would be appreciated. Thanks, Hank

 

[Kodiak99317]

You will probably need a .269 or .270 button with a .272 NK, smaller with Moly of you go that route.

Have you seen http://www.6mmbr.com/6BRFAQ.html ?

 

[Forum Boss]

Seat a bullet and measure the diameter of the loaded round in the middle of the neck. We're typically seeing loaded rounds come in about .2695"-.270", but it depends on the bullet. A .266 or .267 bushing is usually a good choice. A .268 will work but will give very minimal tension. If you're running moly, you'll want more tension, so you may prefer a .265.

 

[EdAtts]

I use a .267 bushing in my 6BR using Wilson Dies. I first had a .269 bushing but this was not enough tension.

 

[jb1000br]

CHAMBER NECK DIAMETER DOESN'T MATTER,unless it is so big that you need a secondary sizing step to bring it down)

I use a .268 TiNit bushing for ~1.5thou neck tension with my unaltered lapua brass.

Would NOT go BIGGER than .268

get a .267 and .268 and see which works best.


JB

 

[Ogre6br]

Can you go to small and have to much tension??

What does to much tension do??
I have a .272 neck and have a 263 bushing,as well as others .267 .268)
I was wanting to give it a try but I dont want mess things up.

Thanks
later
p

 

[Forum Boss]

Yes you can have too much tension. The first thing you notice is the bullet is very difficult to seat--even to the point that some arbor presses will not have enough leverage to get the bullet in. Further, with too much neck tension you greatly increase the chance that the jacket gets shaved or nicked at the case mouth. Neck tension can also affect case pressure--but if you're not crimping also, that's probably not a major consideration if we're talking 2 thousandths of tension vs. 4 thousandths.

From an accuracy standpoint, you'll probably find a sweet spot, using a bushing between .266 and .268. But as your brass work hardens, if you don't anneal, you may have to change the bushing.

 

[Hanic]

Thank you all for the input. Sounds like the range of .266 to .268 is the place to start. Hank