What's the current theory on 30 BR neck diameter?

TomD

TomD

e publius unum
The best 30 BR barrel that I've had was a .335 neck but I don't know how relevant that was to that particular barrel's success. I know current trend in PPC is to thicker necks, is the equivalent trend happening in 30's? I know 30's like a lot of neck tension.

What is the current hot setup?
 
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TomD said:
The best 30 BR barrel that I've had was a .335 throat
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I assume you mean 335 Neck ? I doubt the neck diameter had that much to do with it, a good barrel is a good barrel.

BTW what twist was it ? That might have more relevence than neck diameter.
 
Dick Grosbier said:
I assume you mean 335 Neck ? I doubt the neck diameter had that much to do with it, a good barrel is a good barrel.

BTW what twist was it ? That might have more relevence than neck diameter.
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Yes neck, sorry. Twist was 1:17. I've got a new Kreiger in 1:18 sitting here and I'm wondering if thicker necks are gaining favor as they are with PPC.
 
TomD said:
and I'm wondering if thicker necks are gaining favor as they are with PPC.
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Not that I have heard of, but then while I read a lot about no turn necks here nobody I know of in actual competition shoots no turn or less turned necks. Since most reamers were made years ago and most gunsmiths are not making new reamers just for the purpose of experimentation at least not the ones I know locally.
 
Stay with the .330 neck...

TomD...I recently had a second 30BR barrel chambered...My first one had a .330 neck...I thought I would try a .334 or larger neck, but my gunsmith only had a .330 neck reamer to chamber with, so I stayed with the .330 on the second barrel...and am I glad I did...When I started making some brass for the new barrel, I found about 65% would not clean up at a .011 wall thickness...:eek:
The new Lapua 6mmBR brass just did not have enough "meat" after expanding to 30 caliber to make a good fit on a chamber larger than .330...
I promise you "will not" be at a dissadvantage with a .330 neck..
I think the "Robinette" design 30BR reamer is optimum for the case and bullet combo...
Put a good barrel on a good action/stock and get to it...Learning to shoot a 30BR takes about 500-1000 rounds down the tube before you master the torque...It is a real "badAss" round in score shooting...I ain't been beat by any other caliber since I got thru my rookie gun handleing period...I have shot 250-Xs at 100 yds in the last 6 score shoots, and have (1) 250 score at 200 yds to go with it...I feel like Greg Anderson and Schumacher at the drag races...I am the guy to beat...not an also-ran...;)
 
eww1350 said:
TomD...I recently had a second 30BR barrel chambered...My first one had a .330 neck...I thought I would try a .334 or larger neck, but my gunsmith only had a .330 neck reamer to chamber with, so I stayed with the .330 on the second barrel...and am I glad I did...When I started making some brass for the new barrel, I found about 65% would not clean up at a .011 wall thickness...:eek:
The new Lapua 6mmBR brass just did not have enough "meat" after expanding to 30 caliber to make a good fit on a chamber larger than .330...
I promise you "will not" be at a dissadvantage with a .330 neck..
I think the "Robinette" design 30BR reamer is optimum for the case and bullet combo...
Put a good barrel on a good action/stock and get to it...Learning to shoot a 30BR takes about 500-1000 rounds down the tube before you master the torque...It is a real "badAss" round in score shooting...I ain't been beat by any other caliber since I got thru my rookie gun handleing period...I have shot 250-Xs at 100 yds in the last 6 score shoots, and have (1) 250 score at 200 yds to go with it...I feel like Greg Anderson and Schumacher at the drag races...I am the guy to beat...not an also-ran...;)
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It's been quite a while since I've been to a score match won by anything but. Late last year, my 30 was having some real gremlins so I shot our last score match with my PPC. I got over 30-x for 100 & 200 but wasn't even close to winning. We shoot 200 first and I was close after that but a 30 just powers away on X's at 100. I did shoot 22-X with a 6 once out of many matches but now you have to do that, or better, time after time.
 
Hi Tom.

In one of our HBR chamberings (the WareWolf), we went with a .335 chamber neck versus the more common .330-.332 neck chamber neck diameters for the very reasons you're contemplating thicker necks on a 30BR...effectively more neck tension with less physical sizing of the case necks. Since it's a well known fact that these .30's love neck tension (.005 is not uncommon), we theorized that a larger neck wall thickness would get us to the same place in the 'tuneup' using .002-.003 neck tension..thus avoiding some of the runout issues that can crop up when you're sizing a neck .005-.006 and then seating a flat based bullet.

The .335 chamber neck diameter worked great..but we also found that they still liked the .005-ish neck tension. And that any runout we had (as a result from this much neck sizing) was in actuallity a non-issue since all of our barrels loved being setup with 'heavy' jam...specifically, a seating stem length .030 shorter than the 'just touching' point. We saw this with many, many barrels of different mfgs., numbers of lands, width of lands, etc.

It was at this point that we began to appreciate how much outward radial force a sized neck has.

This spilled over to our work with the .085 neck length .30 WolfPup. I've since been working with some of this stuff in my own 30BR..albeit with a standard .330 chamber neck diameter. All of this led me to rethink neck clearance and the whole 'inside neck' situation...which has completely changed how I make and maintain my .30 cases.

I know this doesn't answer your basic question, but maybe it gives some food for thought as regards this entire area.

And I could be completely wrong...;):) -Al
 
Thank You Al.... It gave "ME" something to think about, and "I'll" be in touch..

Kelly
 
Al,

Interesting food for thought.

The .335 chamber neck diameter assumes a loaded case measures .333 at the neck. Most Lapua brass, after expanding, measures .330-.3315. Loading a flat base bullet brings that dimension up to .331-.3325.

Is the .335 neck your version of a "no-turn" case?
 
hulk:

The .335 chamber is a Hunter BR chamber based off Lapua 308W brass. The 30BR's I have are both .330 chamber necks. I used the .335 chamber as an example of the 'thick neck' approach I believe Tom is considering. -Al
 
I can't think of any logical reason that a case (or batch) should benefit from being turned smaller than what is necessary to clean up the least concentric specimen. What benefits does a thin neck confer other than concentricity? I seems that consistent tension can be more easily maintained with more material.
 
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