Neck Clearance trend

[Joe Salt]

I agree with having at least .003 clearance. And your extraction will even be better. Anyone like to argue about that? Because if you are to tight you create pressure.

Joe Salt

 

[ShootDots]

Neck clearance does not have an effect on accuracy, unless its too tight. Contrary to popular belief the case and or bullet are not centered b y the neck, they are centered by the freebore. Looser seems to be better.

That's a really good point and would explain why ample neck clearance does not harm accuracy.

Obviously when there is not enough clearance we are disturbing a consistent bullet release. Other than that, how can clearance around the neck effect accuracy? Once the bullet has been released it doesn't care how much the neck continues to expand. Aside from working the neck more (anneal) and causing a little more runout during sizing (runout means squat). I have test both runout and neck clearance at 1k, both are a non issue.

Alex, you are asking HOW can not having enough clearance hurts accuracy. The HOW I do not know. The fact that it does, exists. Two REAL LIFE examples: 1.) a friend of mine (on here he is "Smoking-Brass") was using Lapua Palma brass necked to 7mm for his 7mm-08. His loads went in the chamber and extracted fine. However, he was not able to get consistent accuracy. He turned 2k additional brass from his neck and it instantly started shooting more accurately and consistently. 2.) My riflesmith, had some problems with his straight .284. Same deal, not real accurate. He read somewhere (where I do not know>>>maybe even here) so he turned his necks down A LOT (what alot is, I dont know) but he currently has 7K clearance AND it transformed his .284 into one of his most accurate rifles.

It is ironic that BOTH were 7mm and BOTH needed more clearance when they had enough clearance to chamber and extract easily. So the WHY I can't answer>>>but the fact it does, appears to be, without argument..

 

[Warren Dean]

This is an interesting thread. I have always thought that a "tight neck", like 2-3 thousandths clearance, was the best way to go. Apparently I was wrong.

When I got my stock barreled team rifles last year, I was nonplussed when I saw the necks were .344 and my loaded rounds were .338. But the .006" clearance didn't seem to be an issue, as both are extremely accurate rifles.

Now I have an excuse to buy an annealer. ;D

 

[Joe Salt]

Shootdots Think of it this way about Extraction if its already tight it's going to drag coming out! The Brass will only be able to spring back just so much. And you will end up having pressure problem, maybe not on the first firing but then after it will get tighter.

Joe Salt

 

[ShootDots]

Shootdots Think of it this way about Extraction if its already tight it's going to drag coming out! The Brass will only be able to spring back just so much. And you will end up having pressure problem, maybe not on the first firing but then after it will get tighter.

Joe Salt

Oh I understand Joe.. In both of the aforementioned rifles, chambering AND extraction were easy. One of my other friends, Don Diffey, was looking to buy a .284 Shehane. I told him he could use my reamer, a .315 neck. He made up a bunch of UNturned loads and could not even chamber them. He called and asked what was going on. I asked him if he turned his necks down >>> no he did not. He pulled them all out and turned them all down to 13K neck wall thicknes, which allows him 4k clearance. He LOVES his Shehane, even though he shoots F-T/R.

I believe Alex was asking WHY, if you have enough clearance that it shoots and extracts fine, would you necessarily NEED more clearance. A VERY good question indeed! That's why I stated I do not know WHY.. All I know is, is that on more than a few 7mm rifles, if you do not have a fair amount of clearance, your accuracy will suffer. WHY does it appear to be only 7mm's? I can't answer that. My 6.5 x 47's I had all used 3K and were lethal accurate. My new .260A.I. >>>same case>>BOTH my 6 Dashers>>3k and you would be hard pressed to find more accurate rifles. BUT a 7mm! I don't understand that WHY...Only that it appears to be a necessity..

 

[Rtheurer]

Annealing negates the effect of a little more work hardening.

↑↑↑↑

What he said...

Never lose cases to split necks... Not one. I lose cases to loosey goosy primer pockets and or case head separation if I don't set my die up correctly. Never neck splits from over working the neck..so for me its a non issue so far. YMMV

RT

 

[Alex Wheeler]

Shootdots Think of it this way about Extraction if its already tight it's going to drag coming out! The Brass will only be able to spring back just so much. And you will end up having pressure problem, maybe not on the first firing but then after it will get tighter.

Joe Salt

Oh I understand Joe.. In both of the aforementioned rifles, chambering AND extraction were easy. One of my other friends, Don Diffey, was looking to buy a .284 Shehane. I told him he could use my reamer, a .315 neck. He made up a bunch of UNturned loads and could not even chamber them. He called and asked what was going on. I asked him if he turned his necks down >>> no he did not. He pulled them all out and turned them all down to 13K neck wall thicknes, which allows him 4k clearance. He LOVES his Shehane, even though he shoots F-T/R.

I believe Alex was asking WHY, if you have enough clearance that it shoots and extracts fine, would you necessarily NEED more clearance. A VERY good question indeed! That's why I stated I do not know WHY.. All I know is, is that on more than a few 7mm rifles, if you do not have a fair amount of clearance, your accuracy will suffer. WHY does it appear to be only 7mm's? I can't answer that. My 6.5 x 47's I had all used 3K and were lethal accurate. My new .260A.I. >>>same case>>BOTH my 6 Dashers>>3k and you would be hard pressed to find more accurate rifles. BUT a 7mm! I don't understand that WHY...Only that it appears to be a necessity..

You have me backwards. We know not enough clearance disturbs bullet release. I was asking how can too much clearance hurt accuracy (rhetorical)? It cant, as once the neck releases the bullet, the bullet does not care if the neck expands another .001 or .010.

 

[Joe Salt]

Z you are right more won't hurt you but not enough will! When I first started shooting 1000 yard I got Precision shooting Magazine, everyone was shooting tight necks back then, so I thought that was the way to go. I shot alright but not like I do these days and I have a lot less problems with more clearance.. So I don't know if you can go too far the other way, but I'm comfortable where I am.

Joe salt

 

[ShootDots]

Z, I can't imagine even 10-12K making any difference. As long as the case neck expands to properly seal off the chamber area, all should be well.. The only drawback, if it is one, is that you work harden the brass to a faster degree. With the advent of excellent annealers on the scene, that problem should be mitigated to history.

 

[Cassidy]

If neck clearance is less important than previously thought, and as some noted above (if I understand correctly) alignment of the bullet in the freebore is more important to precision 1000 yd shooting, how do you determine the optimal freebore dimensions for the reamer.

 

[Cassidy]

Since the above freebore dimension question is a separate topic from neck clearance, I will start a new thread.

 

[Michaël T]

does anyone know how much spring back there is on new and 7 times fired cases?

 

[memilanuk]

does anyone know how much spring back there is on new and 7 times fired cases?

The latter most likely varies depending on the brand (alloy) and chamber dimension (how much have they been expanded and sized back down every one of those seven firings), among other things.