Thin to Win?
- Thread starter Terry
- Start date
BoydAllen
Gold $$ Contributor
I know a fellow that has a lot of Hall of Fame points, and who has and has had a lot of records, shooting a 6PPC for group. He once told me that he turns necks to achieve a loaded round neck clearance of about 2 3/4 thousandths. Others have said around .003. Dennis Thornbury once told me that he thought that the reason for this is that it gives a more uniform bullet release. Jack Neary has said that the effect shows up more prominently at 200 yards. The neck thicknesses that you mentioned relate to a .262 chamber neck.
Some time back, a well respected long range shooter posted that he and some friends had done some testing and could see not degradation in accuracy at long range when they gradually increased loaded round neck clearance to figures that would exceed those that are typical of the largest factory chamber. Of course at a certain point the brass will be worked more than desirable, and if there is no accuracy gain, there would be little reason to go there.
Some time back, a well respected long range shooter posted that he and some friends had done some testing and could see not degradation in accuracy at long range when they gradually increased loaded round neck clearance to figures that would exceed those that are typical of the largest factory chamber. Of course at a certain point the brass will be worked more than desirable, and if there is no accuracy gain, there would be little reason to go there.
Terry
Gold $$ Contributor
Correct
Raythemanroe
Bullet Whisperer
I feel that there is nothing to gain from not "enough" clearance.. I always suggest to new reloaders .003-.0035 clearance min, no need for less. I also feel that there is no need for excessive clearance, which in my opinion increases the likelyhood of unwanted added run out..
Neck thickness, neck clearance, annealing all work to how much tension you have and I feel effects your tune. You can change either of these and change the tune. Clearance issues can add pressure if not enough .. Really so many reloading questions depends on your specific setup.
Ray
Neck thickness, neck clearance, annealing all work to how much tension you have and I feel effects your tune. You can change either of these and change the tune. Clearance issues can add pressure if not enough .. Really so many reloading questions depends on your specific setup.
Ray
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I talked with two great 1000 yard shooters on this before but I never questioned their reasoning. They BOTH strongly encouraged me to adjust my neck thickness by .0002” at the time when I was just getting into LR BR. So I just did what they said. I am assuming they had done some testing and found what worked best for them or that particular reamer. Hopefully they will chime in.
It’s package deal, Terry. You have to try to determine which bullets you’ll be using and what their pressure ring dimension is. Then you need to decide what neck thickness you are going to run with. I use .0086 on the PPC. Then you need to decide how much neck clearance you wish to have. And then you need a reamer with that dimension.
You can also work in reverse. Decide on a reamer, take the neck dimension on it, add .002 for clearance, add neck thickness dimension, I use .0086, then add the diameter of the bullet at the pressure ring and you are good to go.
Not everyone agrees on what neck diameter and how much clearance is best but my math goes like this: bullet at pressure ring .2434, two neck thickness measures .0086, two clearance measures of .001 = .002 reamer neck dimension = .262, I think.
You can also work in reverse. Decide on a reamer, take the neck dimension on it, add .002 for clearance, add neck thickness dimension, I use .0086, then add the diameter of the bullet at the pressure ring and you are good to go.
Not everyone agrees on what neck diameter and how much clearance is best but my math goes like this: bullet at pressure ring .2434, two neck thickness measures .0086, two clearance measures of .001 = .002 reamer neck dimension = .262, I think.
Terry
Gold $$ Contributor
Thanks
Alex Wheeler
Site $$ Sponsor
I dont believe theres anything to gain with really tight clearance in the neck. I like .003 on a 6mm and more on the bigger cases. There is also a trend to larger neck diameters in an effort to remove as little brass as possible and still clean the necks up. Thicker necks will give more grip and some powders respond well to that.
Carlsbad, you can turn to .0001". Believe it or not. Getting the mandrel fit and cutter edge is critical, then controlling the temperature of everything. Once you get there, you can turn necks well enough that you cant measure the difference with a .0001 mic. Most cutters are too sharp, you want some tool push off to force the neck against the mandrel. Now, Im not saying you can do it quick or profitable like a machinist has to
Carlsbad, you can turn to .0001". Believe it or not. Getting the mandrel fit and cutter edge is critical, then controlling the temperature of everything. Once you get there, you can turn necks well enough that you cant measure the difference with a .0001 mic. Most cutters are too sharp, you want some tool push off to force the neck against the mandrel. Now, Im not saying you can do it quick or profitable like a machinist has to
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Hey..... I didn't know other people did this!
"Thin to win" is specifically a short range (PPC) BR phrase. Just like "throwing loads" is a completely acceptable PPC thing.
IMO a lot of stuff is of dire importance in long-range pressure-ringless loading but immaterial to short-range.
Just like John Force doesn't have a lap time on the Nurburgring
The famous .22 PPC-100 shooter, Bill Forrester was the one who told Jack Neary to use plenty of clearance on his necks if he wanted to win. Bill was well qualified to give advice on accuracy. He is in the Benchrest Hall of Fame, has won the Super Shoot, made match winning bullets and was shooting teen grand aggs long before they became common. Bill doesn't shoot much any more, but one can believe what he says about accuracy. Good shooting....James
Alex Wheeler
Site $$ Sponsor
Long range bullets have pressure rings too.Hey..... I didn't know other people did this!
"Thin to win" is specifically a short range (PPC) BR phrase. Just like "throwing loads" is a completely acceptable PPC thing.
IMO a lot of stuff is of dire importance in long-range pressure-ringless loading but immaterial to short-range.
Just like John Force doesn't have a lap time on the Nurburgring
jackson1
Silver $$ Contributor
Terry, As we spoke on Tuesday, I turn the necks on all my brass. I buy it in lots of 100. My justification for doing this is; getting similar neck tension from each piece of brass. Back in the day when I was using Winchester and Remington brass, it was not unusual to have 0.002" thickness variation on a single case neck. Today, now using mainly Lapua brass in both PPC and BR, outside of fitting to the chamber, turning may not yield much benefit. I have the time, the tools, enjoy doing it, and it is just one less thing rattling around in my head.
I don't consider myself to be in anywhere near the same class of shooter as the Top Shooters mentioned in the above replies or even in anywhere near the same class of shooter as most if not all of you who have replied to Terry's question but from what experiences I have had with Top Shooters I know that one thing they all have in common. They are ALL EXTREMELY PRECISE. That's why they are Top Shooters IMHO.
How this axiom was originally or since has been perceived and interpreted as to it's specific point is another matter.
Again JMHO.
How this axiom was originally or since has been perceived and interpreted as to it's specific point is another matter.
Again JMHO.
Jack Neary is quite a good shooter, also sponsered by Vitouvoori.
I don’t know if it is still part of his well attended, free, seminars held at matches but he also stated, without hesitation, if you gave him series of 5 loaded rounds with 4 of’em cut his way and 1 done at 8.5-8.6, he could tell you every single time which one it was.
I don’t know if it is still part of his well attended, free, seminars held at matches but he also stated, without hesitation, if you gave him series of 5 loaded rounds with 4 of’em cut his way and 1 done at 8.5-8.6, he could tell you every single time which one it was.
BoydAllen
Gold $$ Contributor
If someone is not clear about what the expression means, he should watch the six well done segments of Jack' Presentation on YouTube. It is very clear what he was referring to. It was clearance. At a given chamber neck diameter, turning necks slightly thinner increases the clearance between the necks of loaded rounds and the chamber neck. He takes the trouble to make this very clear, and to relate examples that led him to that practice.
Terry
Gold $$ Contributor
Boyd
I appreciate your point.
I'm looking for more. Would a round with .012 neck thickness but the same clearance shoot the same as a .0081?
We / I have no problem getting enough clearance. My question is the effect of different neck thickness on group size.
I apologise if you were offended by my adaptation of the phrase.
I appreciate your point.
I'm looking for more. Would a round with .012 neck thickness but the same clearance shoot the same as a .0081?
We / I have no problem getting enough clearance. My question is the effect of different neck thickness on group size.
I apologise if you were offended by my adaptation of the phrase.
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