I just measure the neck thickness of a lot of brass I'm using for my "target rifle". I'm getting variations in neck thickness of .001 to .0015. According to RCBS Varmint ammo should be held to .002 variation, and bench rest ammo should be .000 for custom chambered target rifles.

My rifle has a factory barrel and chamber. I'm shooting .55"- .65" 5 shot groups right now. My sized cases show .015 run out on the neck. Loaded ammo averages .002. Will neck turning reduce my group size or is it pointless with a factory chamber? I'd like to hear from some shooters who've measured run out and have practical experience with the effects of neck turning. I want smaller groups, but I'm not a "benchrest" competitor. A .01" decrease in group size is not enough for me to put the work into neck turning. A .2" decrease would make it worth it.

In my opinion unless you have a tight neck rifle you are wasting your time.

Elkhunter, I would tend to agree with JJ but there are exceptions. What kind of a rifle are we talking about here and what is it chambered for? Jim

According to a bench rest competitor that wrote an article I read, the one thing that contributes the most to rifle accuracy is seating depth. I really believe this because I have loaded bullets in my 243Win out so far as to touch the lands and if I do my part it will put 5 shots through the same hole. This is a hunting rifle and I won't load this way to hunt with as the bolt cycle is too stiff. When the slugs are backed up the groups open up.

Normally, it is not considered beneficial to turn for a factory chamber. One reason is that you'll end up working the brass more than you'd otherwise need to, and thus (potentially) reduce brass life. In any event, IF you should decide to turn, you'd only want to turn "minimally" - i.e. simply clean up the necks, with minimum (~.002") neck wall thickness reduction.

Here is what you can do before you decide to turn or not. Sort your unturned brass, and see if brass with consistent necks provide you better groups than unsorted brass.

The level of case neck wall variations you are seeing (.001-.0015) is good. Your runout (~.002") is not bad either. I personally doubt you'd see much improvement even if you manage to reduce these numbers - in particular shooting a factory barrel @ 100 yds (I assume, from your group sizes). But again, sort your loaded ammo, and see if you can discern a difference in group size, then make your choice.

Another thing you can try, is to seat the bullets into the lands. This often negates the effects of runout. But beware of pressures if you do this, and it is less suitable if you have to remove loaded rounds from your chamber.

What caliber are you shooting?? IMHO, the easiest way to reduce group size is to go with a different bullet. If your caliber is either a .224 or .243, there are tons of custom bullets available, which might bring you down in group size. Bullet makers such as Cheek, Fowler, Bart, etc etc make some pretty dandy bullets these days. Worth a try.

- mike

I'm shooting a Savage heavy barrel .243 Win. I has a custom stock and bedding and a good trigger.

I'm shooting the 105 A max from Hornady. I have a good load. My extreme spread is usually 20 or less with a SD of 8 fps. About half the time I can put 10 rnds into a .6" group at 100. I just got the load developed, so I haven't shot it at long range yet.

It sounds like I should stick with what I've got. I may try a Berger bullet just for fun.

I spoke to someone at Sinclair International about Neck Uniforming. He said it was of Marginal value. Although I still do it for Brass Cases, I cannot see any real difference in accuracy between the Nickel Cases I do not “Neck uniform†and the Brass Cases I do….

Elkhunter, If you start with 308 cases and neck them so you have a thick neck and then turn them to what you need you might gain a little. For the work involved and the net return on a bone stock rifle/chamber........it ain't worth the trouble. I do it most of the time with my brass but then again I'm kind of anal when it comes to my brass. Jim

When I'm shooting a factory rifle match, I use neck turned brass. I guess the proper term for me would be neck uniformed brass as its not turned to a specific thickness but turned to clean up 75-80% of each neck. I think this enhances bullet pull and gives me a measurable decrease in my group size. Not enough that I neck turn my hunting ammo.
'course, since you've asked about it, you won't be happy until you've tried it. It wouldn't be a biggy to neck uniform say 10 rounds and try them against your regular stuff. If you're consistantly shooting .5's and .6's, any decrease is gonna small and probably no single thing is gonna make much difference.

I make 7-30 Waters Brass from 375 Winchester.

The brass won't chamber when a bullet is seated, due to the thickness of the neck wall. I turned them down several thousandths and the rounds chamber fine.

I would prefer not to neck turn, but sometimes if the chamber is tight, you do what you have to do.

Good shooting,

HL