I started doing alot of neck turning in the past year and find alot of improvement regarding flyers. This is usually with remington brass. I did a few comparisons, and found my 5 shot group size srank from ~1.5" (with flyers)to .75" consistently at 100 yards.

Just curious for you guys that have neck thickness guages. Approximately, how much will your neck thickness grow with each firing. Say you start out with .015".

What I usually see is thickness varying from 13-18mil or .005" with new remington brass for my 300RUM. I see alot less variation with Federal. I try to never cut my necks less than .014" and try to stay around .015". I heard and found out you can end up in trouble with your FL dies when you get below .011". So I want to know how much the thickness will grow with each firing from a gun like the 300RUM.

Do any of you guys with tight custom throats end up with problems from the neck thickness growing? About how many shots?

I use a tubing mike..........
this one
http://www1.mscdirect.com/CGI/NNSRIT?PMAKA=06233118

The only chambering I have that requires neck turning and probably the only one that benefits is my 6mm 30-30AI wildcat. Because it operates at a lower pressure level than your RUM I can and do turn them to .011" which makes them an excellent fit in a very tight neck chamber. The case has a sharp shoulder angle....... 40 degrees and very little body taper and I believe this plus the low pressure factor minimizes any thckening of the necks. Once turned mine never require it again.

Holland make a good tubing mike for a good price. With a factory chamber, there is no point in taking any more off a neck than to clean it up. Rem. brass isn't the best. Try weighing the brass when clean or new and sort them into seperate groups. You may see more of a group improvement.

Nah wayne, 300RUM brass is 50 dollars/100 pieces. Ain't much sorting and wieghing IMO, doesn't help that much. If it was a 308, or 30-06, I would say yea, just buy a neck guage and cull by thickness and wieght. But for a cartridge like this, where there is only one maker of the brass, I suggest neck turning. (except federal at DL sport)



I am just curious what thickness people like to have. What people suggests is the minimal thickness. And am curious if anyone ever measured how the thickness grows each firing?



Also, is my brass way off base from others? I measured some of the Federal, and don't see near this much variation. Or high and low spots.

Brass only 'grows' from the type of sizing to which it is subjected. If metal is transfered from the shoulder into the base of the neck, such as in FL sizing, the starting thickness in the shoulder will bend around into the base of the neck to start the "dreaded donut". If the neck thickens in another area it's usually because of the stretching at firing, then a transfer of some of the metal when the neck is sized, if you are only neck sizing.

I've been measuring neck thickness religiously on a 338WSM. The reason I have is that those cases are made from 300WSM brass. When you expand the neck to .338, some of the brass in thick shoulders expands into the base of the neck causing eccentric seating of the bullet, and therefore some accuracy problems. I've gone to reaming and turning necks as needed in order to maintain consistency of the loads. What I've noticed is a thinning in one portion of the neck commensurate with a thickening of another portion, usually no more than .001". However, removal of that thickened portion results in gradual thinning of the necks after use over time. This happens during the sizing process. Some necks don't require any turning or reaming many times. In a group of 30 cases you might have to remove metal from maybe 7 or 8 cases.

One set of Norma cases I'm working with right now have been sized 20 times. The necks started off at .0145" after uniforming them. They are now all mostly at just a tad under .0135" which I'd say is pretty good considering in the initial stages they required turning or reaming every load. Now they seem to go 3 or even 4 reloads before any metal has to be removed.

Hope my experience gives you some idea.

As for neck wall thickness, in the larger calibers I like to have minimum .014" necks, however, in the WSM's I've noticed the WW brass is mostly less than that when new. Also, smaller calibers usually end up closer to .012". I don't think those couple of thou's matter much as long as the necks remain elastic and keep a consistent grip on the seated bullets. I anneal every 4 or 5 reloads to insure that consistency.

Thanks bob, I figured you would be the guy looking at this.