Turn/No turn Chamber

[nmkid]

Be gentle! Can someone explain the benefits(?) of a tight chamber vs. no turn chamber. I will be ordering a new barrel for my new build, (6mm-06). I have all the neck turning tools needed. The rifle will be used for varmints at long range. I understand the meaning of the terms and I guess I'm asking which will be better in my accuracy quest with the new barrel.

 

[ShootDots]

Be gentle! Can someone explain the benefits(?) of a tight chamber vs. no turn chamber. I will be ordering a new barrel for my new build, (6mm-06). I have all the neck turning tools needed. The rifle will be used for varmints at long range. I understand the meaning of the terms and I guess I'm asking which will be better in my accuracy quest with the new barrel.

There may be other and more meaningful reason(s) for a "tight-neck" chamber, however, I will give you MY reasons for using a tight neck.

1.) You still need enough room between the chamber walls and the outside of the neck wall to properly allow the bullet to be released. BUT, I like the neck walls on my brass to be "completely cleaned up" and as round as you can get them using a mandrel. Normally, it takes at least 2 thousandths removal of neck wall brass to accomplish that. By forcing an expander mandrel into a case neck, you are pushing the imperfections from the INSIDE of the brass to the OUTSIDE. Then turn those imperfections off;

2.) A "thinner" case neck wall allows for "easier / smoother" seating of the bullet with more consistency in the force it takes to seat the bullet.

3.) It is MY belief that the thinner neck walls allow for more consistent brass after annealing. I do NOT KNOW if that is correct, however it appears to me to be that way.

Whether accuracy is significantly increased from neck turning is not really clear. But what it clear is that it does make for easier, more consistent seating of the bullet. If that translates into better accuracy, good. If it don't, neck turning sure can't hurt.

 

[jr600yd]

You must have clearance between the outside if the case neck and the chamber. The case neck expands to allow the release of the bullet. +1 for what Ben posted.

With a no turn neck there are two schools of thought. The first is accuracy.
Some believe when the neck is the same thickness all the way around the pressure needed to release the bullet will be equal all the way around. This allows the bullet to be more concentric with the bore and not mis-aligned. (Enters the rifling straighter). Does it work? Try it and see. Some say yes some no.

I believe the real benefit of neck turning, or as some say skimming the neck, is brass life. As Ben stated seating a bullet doesn't require as much force. Whether you use bushing dies or ones with an expanded ball the neck is not sized as much. There is a little more room between the case neck and the die. This greatly reduces the amount of case stretch induced by sizing.

In my rifles neck turning or skimming has improved case life. Now if your using a semi-auto rifle that's another story. They are hard on brass anyway and neck turning is probably not worth the effort.

 

[JarheadAZ]

I don't turn necks, but that's because I'm a stubborn old coot. More on this later.

As I see it, the most compelling argument supporting neck turning is that it one of the essential steps to ensuring that the bullet enters the rifling precisely aligned with the bore (and rifling) axis. If you're going to tackle the concentricity issue, skipping the neck turning step will probably completely negate your efforts.

I'll leave the reasons for this up to others who actually do this stuff.

Now, about why I don't. As I said, I'm a stubborn old coot. The key word here is 'old', not 'stubborn'. I don't want to spend one minute of my fleeting remaining time on this planet more than is necessary making ammunition that will hit my target than I absolutely need to. If the ammo will defeat the target, I don't need even a single whit more accuracy than what I already have. Think of it as whether or not that 'Chuck will give a damn whether that round that just took him out was accurate to 1/4MOA or 2MOA. Dead is dead.

I use SAAMI chambers and dies, and the deer and 'Chucks don't seem to care a bit that I completely avoid concentricity and neck thickness issues.

Others' mileage may vary...

Greg

 

[jr600yd]

Since you've made up your mind on the 6/06 (nothing wrong with that) what brass are you going to use? Chances are if your using 30/06 or even 25/06 brass as the parent case your going to have to neck turn after FL sizing. May even have to "skim" again after the first Fire Forming. Oh the joys of the wildcat!

 

[Joe R]

ShootDots said:

There may be other and more meaningful reason(s) for a "tight-neck" chamber, however, I will give you MY reasons for using a tight neck.

1.) You still need enough room between the chamber walls and the outside of the neck wall to properly allow the bullet to be released. BUT, I like the neck walls on my brass to be "completely cleaned up" and as round as you can get them using a mandrel. Normally, it takes at least 2 thousandths removal of neck wall brass to accomplish that. By forcing an expander mandrel into a case neck, you are pushing the imperfections from the INSIDE of the brass to the OUTSIDE. Then turn those imperfections off;

2.) A "thinner" case neck wall allows for "easier / smoother" seating of the bullet with more consistency in the force it takes to seat the bullet.

3.) It is MY belief that the thinner neck walls allow for more consistent brass after annealing. I do NOT KNOW if that is correct, however it appears to me to be that way.

Whether accuracy is significantly increased from neck turning is not really clear. But what it clear is that it does make for easier, more consistent seating of the bullet. If that translates into better accuracy, good. If it don't, neck turning sure can't hurt.

nmkid,
A word to the wise, if I were you I'd print what Ben said and post it next to your reloading press, and read it each time before you start reloading.

I know Ben personally and IMO he is a world class shooter. It doesn't matter if it's 102 degrees with enough mirage to make you see dancing girls or enough wind on a winter day to make wonder why you're not home. It doesn't matter if its 300 yards or 1,000 yards most of the times he finds a way to win most F-Open class matches down here in Houston. He occasionally has a bad day and drops a couple of points. Guys like me have to look up to see the bottom of his shoes.

I've slowly implemented every suggestion he has made and my scores have steadily improved as a result. Upon his recommendation this week I started thinning my .308 cases to levels I wouldn't have ever considered and most guys say it's unnecessary. I expect my accuracy to improve next time I get to the range. He has helped me get from Marksman to Master in a year in mid-range F-TR.

Kindest regards,

Joe

 

[nmkid]

Since you've made up your mind on the 6/06 (nothing wrong with that) what brass are you going to use? Chances are if your using 30/06 or even 25/06 brass as the parent case your going to have to neck turn after FL sizing. May even have to "skim" again after the first Fire Forming. Oh the joys of the wildcat!

I will be using 25.06 cases. I'm prepared(?) for the neck turning.

 

[nmkid]

Be gentle! Can someone explain the benefits(?) of a tight chamber vs. no turn chamber. I will be ordering a new barrel for my new build, (6mm-06). I have all the neck turning tools needed. The rifle will be used for varmints at long range. I understand the meaning of the terms and I guess I'm asking which will be better in my accuracy quest with the new barrel.

There may be other and more meaningful reason(s) for a "tight-neck" chamber, however, I will give you MY reasons for using a tight neck.

1.) You still need enough room between the chamber walls and the outside of the neck wall to properly allow the bullet to be released. BUT, I like the neck walls on my brass to be "completely cleaned up" and as round as you can get them using a mandrel. Normally, it takes at least 2 thousandths removal of neck wall brass to accomplish that. By forcing an expander mandrel into a case neck, you are pushing the imperfections from the INSIDE of the brass to the OUTSIDE. Then turn those imperfections off;

2.) A "thinner" case neck wall allows for "easier / smoother" seating of the bullet with more consistency in the force it takes to seat the bullet.

3.) It is MY belief that the thinner neck walls allow for more consistent brass after annealing. I do NOT KNOW if that is correct, however it appears to me to be that way.

Whether accuracy is significantly increased from neck turning is not really clear. But what it clear is that it does make for easier, more consistent seating of the bullet. If that translates into better accuracy, good. If it don't, neck turning sure can't hurt.

My Douglas barreled 25.06 has always been on the verge of being a good. I have bunches of groups at 1/2"+-. The smith that put this rifle together is no longer working and about 2500 miles away so I don't have any info on the chamber on this rifle. That being said, I was turning my necks not knowing or having any idea what kind of chamber it had. The barrel had already been turned when I bought it sight unseen. Right or wrong I had turned some cases to .013+- before I even had the rifle. Well, long story short...I took to heart your suggestion on cleaning my necks up completely. My cases ended up at .0125. I changed nothing else, (powder, primers, etc.) Today I went to the range and my first group measured .377. I was jumping for joy! So if I do nothing else...I will be driving to the new gunsmith's shop and hand delivering my action. I'm sure this new gun will have a chamber that will necessitate neck turning.

 

[ShootDots]

NMKID, Excellent! I believe you will be doing yourself a great service! Glad to hear it is working out for you!

 

[masterblaster1]

Other than what is written below, which is my approach too you could have a chamber that is cut tight at the neck to accept some of the heavier brass necks.

Be gentle! Can someone explain the benefits(?) of a tight chamber vs. no turn chamber. I will be ordering a new barrel for my new build, (6mm-06). I have all the neck turning tools needed. The rifle will be used for varmints at long range. I understand the meaning of the terms and I guess I'm asking which will be better in my accuracy quest with the new barrel.

There may be other and more meaningful reason(s) for a "tight-neck" chamber, however, I will give you MY reasons for using a tight neck.

1.) You still need enough room between the chamber walls and the outside of the neck wall to properly allow the bullet to be released. BUT, I like the neck walls on my brass to be "completely cleaned up" and as round as you can get them using a mandrel. Normally, it takes at least 2 thousandths removal of neck wall brass to accomplish that. By forcing an expander mandrel into a case neck, you are pushing the imperfections from the INSIDE of the brass to the OUTSIDE. Then turn those imperfections off;

2.) A "thinner" case neck wall allows for "easier / smoother" seating of the bullet with more consistency in the force it takes to seat the bullet.

3.) It is MY belief that the thinner neck walls allow for more consistent brass after annealing. I do NOT KNOW if that is correct, however it appears to me to be that way.

Whether accuracy is significantly increased from neck turning is not really clear. But what it clear is that it does make for easier, more consistent seating of the bullet. If that translates into better accuracy, good. If it don't, neck turning sure can't hurt.

 

[amlevin]

This allows the bullet to be more concentric with the bore and not mis-aligned.

Maybe in some chambers, like factory, this is an issue. On my rifles where the lead diameter is the same as the bullet diameter there's not much chance of misalignment as the bearing surface ahead of the case is already lined up with the rifling. My .224: diameter bullets are held in a .224" diameter "cylinder" when chambered and the case merely aligns itself.

As for removing .002" to clean up cases, I'm able to do that with far less material removal from my Lapua brass.