A shooter question got me to thinking.

[Willie]

A couple of months ago, I was checking drops at 600 yards adjacent to a guest at our range. He was shooting a 280 A.I. built on a 700 action with 750+/- round count. During a cease fire, he retrieved his target and it impressed me. He had fired 10 rounds into a helluva group over one hour's time. Nine were in a hair over 1-1/2" and one opened group to 2-1/4". I was very humbled, to say the least.

We got to talking and he said the first 3 firings on his set of brass never did better than 1/2 moa from 100 to 400 yds with the exact same sizing and same powder lot and charge, but on the fourth firing all rounds were shooting tiny groups. He then told me he thought the neck's thickness had evened out. WTH, I thought to myself. All I could do was smile and tell him "You're just shooting better". Then it was "Your brass is hardening to the point where your die is setting your neck tension perfect to shoot better".

He was adamant about it being his case necks were now the same thickness. He pulled a file of his targets out and walked me through it, explaining each firing on that set of 50 cases. He was a damn fine shooter and kept good records. He went on to tell me how x # of cases showed no neck growth after 2 firings and the rest showed no growth after 3 firings.
He then got my attention when he stated " After the neck's stop growing, the necks flow (in the elastic state) to even out the thickness".

I didn't know what to say, except " Interesting Theory ". I didn't have my ball mic with me, so I couldn't dispute his theory. I turn for all my rifles, so I had never tested his comment. After he left, I started to doubt my feelings, that he was dead wrong. Couldn't hit the side of a barn, after all that.

Somebody tell me I was right and he was wrong, before I get any crazier than I am. At the time, I forgot to ask him about the specs on his rig.

 

[ireload2]

He can have all the theories on earth but there is not any magic. A ball mike is the only way to know that he is full of hot air.

 

[Mulligan]

I have no helpful information as it relates to neck thickness evening out on its own. However, I can say without hesitation, my dasher brass is "better" after 3-4 firings. Nothing I can measure, maybe because of ignorance on measuring tools and proceedures but the target and my trusty dial caliper......and the scorekeeper say my groups are better.
CW

 

[fguffey]

I forgot to ask him about the specs on his rig.

http://bulletin.accurateshooter.com/2009/05/ken-brucklacher-sets-1000-yard-score-record-100-8x/

F. Guffey

 

[BoydAllen]

It may be that what is happening is that the necks become work hardened to a more uniform condition rather than their thicknesses evening out. Contrary to what one might expect, new brass may not be all that uniform in hardness. I base this on experience working with magnum brass that did not bump uniformly with the same die setting until it had been "stress relieved" (heated to a less than fully annealed but more uniform condition) using a rotary two torch annealer. It may be that the shooter's cases reached a maximum of work hardening after a few firings, and that that condition produced a more uniform bullet pull. Or he may have been working with a powder that liked the resultant bullet pull better than that of new brass. I find it common that shooters may not consider so called neck tension as a variable to be fully explored when working up loads. In any case, whether or not his theory was correct, his results should be noted. Not knowing the precise mechanism by which a thing works should not prevent us from befitting from the fact that it does.

 

[Erik Cortina]

He had his seating depth wrong (too long) to start off with and throat erosion finally put him in the sweet spot. This happens often.

 

[Willie]

Boyd --- That was one of the things I suggested to him.
Erik --- That is certainly a possibility and I didn't think of it, at the
time. His round count would account for that.

When I was shooting factory rifles, I admit, I never noticed any that suddenly started shooting noticeable better, with multiple firings on brass.

My first impulse was to write the guy off as a nut. His hypothesis was something that didn't jive with anything I'd heard of. Still, the more I thought about it, I thought that MAYBE in a 40* shoulder with a minimal neck diameter ----- it might be possible. I have ZERO knowledge on brass movement in the "elastic state" other than neck length growth. Hell, if it worked for him, many others would have noticed it and passed their findings on and it would be common knowledge.

Maybe, he'll show up again and I'll be better prepared to challenge his belief. Yes, my extra ball mic is now in my range bag. I do appreciate the responses from more knowledgeable shooters.

 

[BoydAllen]

I don't claim to know much about this theory, because this is the first that I have heard of it. I do know one thing. I have re-turned necks that had seen a lot of service and seen how uneven the cut was, compared to what it looked like after turning the first time. We really do not know if the entire inside surface of a new case that has been expended for turning is a perfect cylinder...and if it is not, the turning mandrel will ride on the "high"spots, and the turned OD will be look great, while the internal ups and downs will result in variations in thickness. Some years back, a friend who was very much into the best brass prep for his 6PPCs told me that he and a buddy would run s their unturned but expanded .220 Russian brass through a one piece die with an expander ball several times to "iron out" the necks before turning.

 

[Lapua40X]

Seems to me that, if you are the proud owner of a ball mic,, it's not difficult to test the theory. Take some virgin brass, mic. the neck thickness, shoot/reload/shoot a few times, and mic. again. Sure is easier than sharing a lot of theories that may or may not prove to be accurate.

 

[Brians356]

I wouldn't lose any sleep grappling with this, or let it turn your world upside down. I don't think he has much invested in his "hypothesis" which is actually just a supposition. And he has probably never measured and tracked the neck wall dimensions so how could he? He probably rather enjoyed your evident consternation trotting out alternative explanations.

My own hunch is there is no force vector involved compelling enough to migrate brass from the thick to the thin side of the neck, certainly not so significantly in so few firings. Brass only flows under extreme pressure, and when it must be displaced somewhere - both.
-

 

[kvd]

So how does brass constrained in all directions during firing lengthen to the point where it will not fit in the same chamber it was fired in and pulled from after two or three firings?

I've checked neck thickness after a few firings and admittedly found no measurable difference from when they were first turned. As BoydAllen suggested, maybe there is an "ironing out" effect from the heat and pressure of firing. This in turn may result in more uniform bullet grip - especially if one doesn't anneal.

My 2¢ worth.

Ken

 

[fguffey]

Seems to me that, if you are the proud owner of a ball mic,, it's not difficult to test the theory.

And it seems to me the old theory about the Rat Turd in the violin case makes less sense now than it did when it was first said. Ken Brucklacher made no claims, he purchased cases, loaded them and then set a world record with a magnificent rifle. Draw a conclusion? Ken Brucklacher is a very good shot.

Nothing was said about measuring the cases fired by Ken Brucklacher, I believe it would have been interesting has someone measure the case before and again after firing.

F. Guffey

 

[fguffey]

And then there are all of the problems reloaders have trying to figure out what happens to the case shoulder when sized; I believe they have the same problems trying to decide what happens to the neck and shoulder when fired. If a member wants to get holler at respond to a question about 'donuts'. I ask; is it stretch or is it flow or is it both; stretch and flow.

F. Guffey

 

[Brians356]

So how does brass constrained in all directions during firing lengthen to the point where it will not fit in the same chamber it was fired in and pulled from after two or three firings?

Brass doesn't flow forward much into the neck, lengthening the case overall (If that's what you refer to) until it is resized in a FL die, inside which it is not constrained in all directions. But neither is it constrained in all directions while in the chamber.
-

 

[dcali]

I've never noticed necks changing thickness. What I have noticed is that it is easier to get a consistent shoulder bump after the third firing than it is after the first. Brass does change as it is fired/sized, but perhaps not in the way he thought.

 

[dickn52]

It may be that what is happening is that the necks become work hardened to a more uniform condition rather than their thicknesses evening out. Contrary to what one might expect, new brass may not be all that uniform in hardness. I base this on experience working with magnum brass that did not bump uniformly with the same die setting until it had been "stress relieved" (heated to a less than fully annealed but more uniform condition) using a rotary two torch annealer. It may be that the shooter's cases reached a maximum of work hardening after a few firings, and that that condition produced a more uniform bullet pull. Or he may have been working with a powder that liked the resultant bullet pull better than that of new brass. I find it common that shooters may not consider so called neck tension as a variable to be fully explored when working up loads. In any case, whether or not his theory was correct, his results should be noted. Not knowing the precise mechanism by which a thing works should not prevent us from befitting from the fact that it does.

AND, he's fire forming everytime he fires it unless he's annealing and playing with them.

 

[Canadian bushman]

I've never noticed necks changing thickness. What I have noticed is that it is easier to get a consistent shoulder bump after the third firing than it is after the first. Brass does change as it is fired/sized, but perhaps not in the way he thought.

+1

I always notice it takes a couple firings for brass to fully fireform to a chamber. Especially with a wildcat.

 

[JAlfred]

Ok, I just stepped over from the kiddies table to ask a question. If he isn't annealing, his neck tension has probably changed (decreased)?

 

[/VH]

Ok, I just stepped over from the kiddies table to ask a question. If he isn't annealing, his neck tension has probably changed (decreased)?

JAlfred,
I followed you over from the kid's table too but I expect whether his neck tension decreased or increased would be somewhat dependent upon his sizing procedure... basically whether his last step in sizing the necks expands or reduces their diameter.

One other potential kink I see regarding the discussion of the ball mic, above; exactly what will the ball mic tell you if you didn't measure the neck walls prior to those cases being fired? Admittedly, I don't think I've ever measured a new, unfired, unsized, unturned case neck that showed a uniform wall thickness, to less than about .00075", or so. If I have, it has been rare enough that I don't recall seeing it.

 

[JAlfred]

JAlfred,
I followed you over from the kid's table too but I expect whether his neck tension decreased or increased would be somewhat dependent upon his sizing procedure... basically whether his last step in sizing the necks expands or reduces their diameter.

One other potential kink I see regarding the discussion of the ball mic, above; exactly what will the ball mic tell you if you didn't measure the neck walls prior to those cases being fired? Admittedly, I don't think I've ever measured a new, unfired, unsized, unturned case neck that showed a uniform wall thickness, to less than about .00075", or so. If I have, it has been rare enough that I don't recall seeing it.

There are a lot of potential variable and interesting question to kick around. I learn a lot around here.