• This Forum is for adults 18 years of age or over. By continuing to use this Forum you are confirming that you are 18 or older. No content shall be viewed by any person under 18 in California.

30br neck clearance

Leadfarmer

Silver $$ Contributor
I've read every thread on here and bench rest central going back to 2006. I've noticed that neck clearance has evolved somewhat from super tight to looser.

I'm going to be turning some brass for a 30br .330 neck and was thinking .0095 neck wall thickness to give me .0022 with fatter bullets and .26 clearance for the skinnier ones.

Is that too much clearance? Should I go with .0096 or even .0098 neck wall thickness? My last 30br was a .332 neck and was .330 under a loaded round and shot pretty darn good.

Any suggestions, what's all your clearances?
 
Leadfarmer said:
I've read every thread on here and bench rest central going back to 2006. I've noticed that neck clearance has evolved somewhat from super tight to looser.

I'm going to be turning some brass for a 30br .330 neck and was thinking .0095 neck wall thickness to give me .0022 with fatter bullets and .26 clearance for the skinnier ones.

Is that too much clearance? Should I go with .0096 or even .0098 neck wall thickness? My last 30br was a .332 neck and was .330 under a loaded round and shot pretty darn good.

Any suggestions, what's all your clearances?
Click to expand...
My 30BR chamber is .330. I turn my brass to .096 with no issues.
 
Clancy said:
I’d turn for .003 clearance with your fattest bullet seated.
Click to expand...
With the fattest bullet? With the barts or similar I'd have roughly .0034 or a tad more clearance. That's interesting. I noticed people saying they were getting better groups at 200 yards with .003 clearance, even though ill be strictly 100 yards, I'll take this into consideration. I have a feeling I'm overthinking all this.
 
Leadfarmer said:
With the fattest bullet? With the barts or similar I'd have roughly .0034 or a tad more clearance. That's interesting. I noticed people saying they were getting better groups at 200 yards with .003 clearance, even though ill be strictly 100 yards, I'll take this into consideration. I have a feeling I'm overthinking all this.
Click to expand...
Clearance is a good thing. I’ve seen it over and over where .003 outshot .002, although not in 30 BR specifically.

I set everything up for .004. I’m to the point I’d rather have .006 than .002.
 
I started out last year with my first 30br I wanted to learn how to turn necks aswell I started out with 2 to 3 thousandths neck clearance. And found after several firings some of my brass was tight going into chamber. I returned everything. And that fixed my problem. I got new brass now and now use 3 to 4 thousandths neck clearance with a 324 bushing. for a .330 neck cjamber. I shot a 24x Saturday morning. Was pretty satisfied with it all.
 
I don't turn the necks by the math. I set mine up for .003 clearance on the fattest bullet, measured with a good .0001 micrometer over the pressure ring of a seated bullet. Necks can tend to thicken a few tenths on new cases before they settle down so keep that in mind.

In my experience, you can run into on-target accuracy issues with too little neck clearance on a 30BR before they feel or measure 'tight'.

My 2 cents worth.... -Al
 
Last edited:
AlNyhus said:
I don't turn the necks by the math. I set mine up for .003 clearance on the fattest bullet, measured with a good .0001 micrometer over the pressure ring of a seated bullet. Necks can tend to thicken a few tenths on new cases before they settle down so.

In my experience, you can run into on-target accuracy issues with too little neck clearance on a 30BR before they feel or measure 'tight'.

My 2 cents worth.... -Al
Click to expand...
You ate so correct. I have been called everything but a humsn being on 2 forums for saying necks thicken. As a long time .262 neck guy with several different 6mms and the user of a tenth mikes......I know what I have measured for many years. One of those who ripped into me is viewed by many as an 'Authority'. I enjoyed reading your comment. When I cut necks I leave my cutter set and after 4 firings run it back over them. Some you see nothing, most you need fine dust comming off, and a few you say, Wow, where did this come from.
 
If you form 30 BR brass from 6BR Norma it gets pretty thin at the neck shoulder junction. Leaving the neck a bit thicker on the first cut until you get a couple of fireforms and then turning again to eliminate the thicker neck is best in my opinion. I have a .330" neck on my chamber and use a .325" bushing. I'm using Peterson 7 BR brass now.
 
JEFFPPC said:
You ate so correct. I have been called everything but a humsn being on 2 forums for saying necks thicken. As a long time .262 neck guy with several different 6mms and the user of a tenth mikes......I know what I have measured for many years. One of those who ripped into me is viewed by many as an 'Authority'. I enjoyed reading your comment. When I cut necks I leave my cutter set and after 4 firings run it back over them. Some you see nothing, most you need fine dust comming off, and a few you say, Wow, where did this come from.
Click to expand...
Turned necks thicken on my 30BR and 6PPC brass after two to three firings.
 
JEFFPPC said:
You ate so correct. I have been called everything but a humsn being on 2 forums for saying necks thicken. As a long time .262 neck guy with several different 6mms and the user of a tenth mikes......I know what I have measured for many years. One of those who ripped into me is viewed by many as an 'Authority'. I enjoyed reading your comment. When I cut necks I leave my cutter set and after 4 firings run it back over them. Some you see nothing, most you need fine dust comming off, and a few you say, Wow, where did this come from.
Click to expand...
That's good to know. Im just ordering a PMA model b, but I'll check the thickness and just turn again after 4 firings. Don't need to worry about setting anything, the fellas at PMA will do it for me, haha!
 
I shot a set of targets a few years ago, with a varmint rifle of all things, that was the best agg I’ve shot at .177.

There was nothing extraordinary about the conditions. Just a cool day about 6 mph with a hint of thermal mirage off the barrel.

The only thing that stood out was I was using leftover, virgin Peterson brass that I turned for .0035 clearance in a .268 neck- BUT this was a .272 no turn 6BR barrel. That’s .0075 of clearance.

Now, I’d never do that on purpose, but it’s a sure and definitive sign that too much won’t hurt a thing. While, on the other hand, I’m absolutely certain that too little will.
 
Well after reading these I'm going to go with .0095 necks. That'll give me enough clearance I think and if not I'm going to order a PMA model a and set my own and experiment with more clearance in the future builds.

@AlNyhus , or anyone else, are you guys using a 30 or 35 degree cutter? Feel like I read 35 degree won't dig into the shoulder as bad and allow you to blend the cut better? This is my first go at this. Last batch I sent off to have done.
 
LCazador said:
If you form 30 BR brass from 6BR Norma it gets pretty thin at the neck shoulder junction. Leaving the neck a bit thicker on the first cut until you get a couple of fireforms and then turning again to eliminate the thicker neck is best in my opinion. I have a .330" neck on my chamber and use a .325" bushing. I'm using Peterson 7 BR brass now.
Click to expand...
Yes I agree with that 100%. When I was learning. I had many neck separations. Mainly on the first firng. I actually leave a small hump ther now and after 2 firings it's gone
 
NC/Br Shooter said:
Yes I agree with that 100%. When I was learning. I had many neck separations. Mainly on the first firng. I actually leave a small hump ther now and after 2 firings it's gone
Click to expand...
May I ask what you mean by small hump? Like at the neck shoulder junction? My understanding was that the brass will thicken regardless just due to the flow of it going forward. I also might be talking out my ass as well, Haha.
 
You must log in or register to reply here.

Upgrades & Donations

This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.


Click Upgrade Membership Button ABOVE to get Gold or Silver Status.

You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.


To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.

Classified Ads

Forum statistics

Threads
165,861
Messages
2,205,013
Members
79,175
Latest member
rlk99

Share This Page

Back
Top