Case neck sorting tool or ball micrometer?

[dboyles]

I've got about 500pc of Lapua .223 that is now once-fired through my gun. I measure my reloads carefully, but one piece missing from my bench is a way to measure neck thickness variations. My chamber does not require neck turning, but I'd like the ability to sort brass based on neck thickness; specifically, on variations in neck thickness.

For a while I have had in my mind that I'd buy a Sinclair/Starret ball mic with a stand. Now I'm wondering if I would be better suited with a tool that uses an indicator, like the Sinclair neck sorting tool. That would seem to get the job done, and at less than half the cost of a ball mic, and would probably let me sort hundreds of pieces relatively quickly.

Am I on the right track here, or is a ball mic something that I definitely need on my workbench?

 

[jbarnwell]

I have both and both work well. As Sinclair list them one is a sorting tool, it's easy to read and allows you to sort case necks quickly. The ball mic can be used to sort also, but is a little more difficult read. IMHO the ball mic really shines when turning case necks to precision tolerances as it reads down to the ten thousandth. I bought this tool when I started shooting the 6ppc. Hope this helps.

Jarvis Barnwell

 

[dboyles]

Thanks; that's a good point about the precision/resolution that the tools provide. What's an acceptable ES for neck thickness variation in a sorted batch? For loaded rounds' neck diameter on this lot of brass, I see an ES of .0007" (from .2500" on the low end to .2507" on the high), Does that imply that I might be chasing my tail in sorting brass on neck thickness? Is there any reason for me to sort based on the actual neck thickness measurement, or should I just worry about the variation within each piece of brass?

Although not a benchrest gun, it'll shoot honest 1/2 MOA 5-shot groups "all day long," but I feel like with perfect brass I could do just a touch better.

 

[BoydAllen]

There are a lot of factors that come into play when your accuracy goal is below a half inch. I think that the mic. is too slow for sorting large numbers of cases. I have one. What sort of rest/bag setup do you use? How did you work up your load? Where are you bullets seated in relation to the rifling? Are you shooting with some sort of wind flags? What dies are you using? How straight is your ammunition? Typically, when someone tells me that he wants to get better results, I give him a list of things that need to be changed. The usual response is that he doesn't want to do any of them, because they are too much trouble. In the past, I tuned up a factory .222 and .223 to accuracy that was consistently under half inch, when the wind was cooperating, with American brass, that was all from the same lot, but unturned and unsorted. I tried turning necks, and could see no increase in accuracy. IMO Lapua brass is good enough that you may be wasting your money and time looking in this area. If I were you, I would play with seating depth and shoot over some home made flags. This assumes that your bench equipment is up to standard, and you have good technique. Another thing that really helps is having a good trigger. What is your trigger pull? What kind of rifle are you shooting?

 

[mikecr]

The indicator setups do not work as well, nor do they really save any time.
For one thing, to use them with any hope of success means prepping the case mouths first.
Not needed with a mic.
Mic anvils rest more consitently against necks, and read actual thickness better than indicator anvil & mandrel do.

I've tested both side by side.
Don't waste your money on shortcuts.

 

[dboyles]

Thanks for the feedback, Boyd. The rifle is one that I had Mark at Short Action Customs build for me, and I'm just now getting through the first firing on my lot of brass, which was good enough out of the box that I only ran it through an expander die (.001" under bullet diameter) to even out neck tension, although that was already very consistent out of the box. I have experimented with sizing methods on a smaller lot of Lapua brass and settled on using a Redding Type S die minus the bushing as a body die, and probably a Lee collet neck die for the necks. I bought the Lee only recently after not getting the results I wanted with the Redding stuff, even in my Co-Ax press. I want to say that in my limited testing the Lee cut neck out-of-roundness in half (say, from .002" to .001"). I've got micrometer seating dies from Redding and Forster and will see which one I like better when I get around to it. I have done a lot of loading with the Redding but got frustrated with it one day and ordered the Forster to try. I think I may still prefer the Redding.

Anyway, I shoot with a bipod (Atlas) and rear bag (TAB or Dog-Gone-Good; it varies) both from the bench and prone. I prefer to shoot the rifle prone, but move to the bench when mirage gets too bad or when I'm not happy with how well I'm shooting prone. Wind reading is not in my repertoire, so I usually confine my load development to calm days. 200 yards is as far as I get to shoot on a regular basis. Needless to say, the shooter is responsible for more fliers than the gun or the ammo. Still, I like tinkering, especially when the weather doesn't make for a pleasant day at the range.

I have not experimented extensively with seating depths. Currently I'm using a jam of .010-.015" (75gr A-max). I also haven't played with primers. A lot of that is down to the fact that I'm trying to get my case prep as good as possible before I take my load development any further.

Here is an example of what I consider pretty decent shooting from both me and the rifle: 10 shots, 200 yards, prone, starting with a cold barrel. It measures .866" center-to-center. Unremarkable by many standards, but good by my own. I suspect the slight horizontal nature of the group is down to the shooter and maybe a touch of wind.



Mike, I just saw your post and wanted to thank you, too. You've identified a couple of concerns that I had, and I appreciate the input.

 

[BoydAllen]

Good report. A lot of shooters shy away from some way to look at the wind. I suggest that having some sticks and surveyors' tape in front of you won't be expensive, or cause any problems, and over time, you will learn to speak their language. No serious accuracy testing can be done without them. You will be trying to fix things that probably not need fixing, that were simply caused by the wind. The good news is that you seem to be a talented shooter, that has some good equipment. Carry on.

 

[dboyles]

Thank you, Boyd. I'll take the compliment but I need to find my way into competition to see if playing at the range translates into shooting good scores. I'll put together some wind flags (and I need to start keeping better notes) before my next trip out to the range.