Home Forums Reloading Big Game Rifles Concentricity

Gentlemen,
I am at a loss. Here is my dilemma.
I am using a Redding T7 press. Redding dies and competition bullet seater and Redding competition shellholders. Imperial sizing die lubricant and graphite inside case neck lube.
Reloading for my 280 Ackley Improved
Nosler Brass. New brass is as those of us who have used Nosler brass know are ready to load. I checked the new brass on a Sinclair concentricity checker for neck runout and found that most new brass rolls under .002" although several out of a box of 50 new brass will roll .003"-.004".
I am loading 145 Barnes LRX's but have tried 140 NBT's, and 140 Berger VLD Hunter to determine if the concentricity I am seeing is bullet related. The roll out issues I am seeing do not discriminate.
All new brass primer pockets are uniformed and all necks are chamfered with a Sinclair VLD tool. Out of a new box of 50 brass loaded (40) loaded rolled less than .003". Ten of them rolled between .004" to .008".
Once fired brass all come out of the chamber barely moving the needle on the dial indicator. Melvin Forbes did a nice job cutting a chamber in this one.
Fired rounds are .318' neck OD. Loaded rounds neck OD are .3115"-.3120" OD (neck thickness varies .0005" to .001" on the brass). I have .306,.307, and a .310 Nitride bushings and am using an "S" type Redding FL sizing die. The 310 bushing is too big so since I have it I use the 307 bushing with a carbon floating expander. A .308 or a .309 bushing would probably be a tiny bit better than the .307 not working the neck quit as much but since I have the 307....
Necks are all brushed, graphite lubed inside and the drag back thru the neck is light and slick. Resized neck .3095" to .3100" giving the round .002" squeeze. Shoulders are all bumped .004". 20 loaded once fired rounds 15 will roll less than .003" and 5 will roll between .005" and .008"
The gun shoots awful good but I sort the rounds and the rounds that roll between .005 and .008 are wild cards especially the 7's and 8's. I will know more about them after the next range session as I have been shooting plates and have no chronograph readings on the high roll rounds. I am sure they will jack the extreme spreads up. No way would I hunt with them.
Any help here would be greatly appreciated. Going to hit the hay and load several in the AM later today. Hoping I can get them to all come out of the press at less than .003".

Thanks,
Dave

Are the same cases the ones that are giving you the runnout, if so, the brass is likely thicker on one side and they will never be good. Mark the cases and see if they repeat.

I would get a .310 bushing, remove the expander ball and not bump the shoulder more than .002. I do not FL size on every firing, never found that to be beneficial. Also you need to determine at what point you are introducing the runout. Measure it after each step in your process my guess is either the shoulder bump or bullet seating.Rick.

Nothing you can't fix by turning the necks.

Yep. Turn/ream the necks.

I had the same problem with 20 Tac and 223 cases. Got rid of all the commercial brass and obtained 700 rounds of LC brass.

My procedure:
I turn around 1 thou. from the case necks.
Sort by weight putting those within 1 gr. together.
Move the expander plug up into the die.MD recommende.
Full length resize
Then I use a Lee neck sizer to neck size the cases. This appears to correct runout.

My results are really spectacular. Very seldom do I get a flier and my runout is within 1 thousands, usually 1/2 thou.

Before I was getting run out with .002-.004 which resulted in fliers. I have yet to find a good reason not to turn necks. Results with my shooting partner have followed mine.

Since the necks only vary in thickness by .001" max, that's probably no the problem. Or at least I've never had .001" difference in neck thickness prevent handloads from shooting well in big game rifles. But turning the necks still might help, because thinner necks might fit one of the bushings better.

The easiest solution would be to get the right size neck bushing, and then not use the expander ball at all. I know Redding recommends using the expander with S dies, but I almost never do.

I hear what you're saying, but I'm not totally sure the OP meant he directly measured neck walls with a ball mic or the like.

If you have cases that are thicker on one side, just turning the neck won't always fix the problem. That is why we label our best cases and use them for matches. A bad case is a bad case. The only thing I can figure is that the brass isn't uniform somewhere that you can NOT fix it.

Yep, if a case is uneven in the neck it's also likely to be uneven in the body. If it's bad enough, the case will have a little curve to the body even after FL sizing.

John and Dennis and Others,

Thanks for all of your responses regarding the concentricity issues I was having. Just getting back on as I have been pretty busy and doing a lot of hunting and shooting.
I figured out the concentricity issues with my 280 Ackley and thought you gentlemen would like to know what I finally came up with that corrected the problem.
I originally posted that the fired rounds were .318" O.D. when in fact they are .320". I made a trip up to Melvin's and his reamer is .321" which is a little big for a 280 Ackley chamber. In order to get the interference fit for the 140 VLD Hunters where they will stay put a .307" bushing is used in the final sizing operation in a FL Redding S die with no expander.
To keep the run out on the brass under .003" I had to start with a .316" bushing in an S Neck Die and run every case through then go to a .311" bushing in the neck die. Final sizing is a .307" bushing in a FL S die and the concentricity is <.003" and many are .001"
I read a gentlemen's post who explained after much testing that brass (necks) can only be reduced in size a maximum of .005" per sizing or concentricity issues are introduced. His testing and account of the results have proven to be correct.
In addition the brass moving from .311" loaded to .321" works the brass a bunch and after two firings the brass needs annealed. It gets noticeably harder.
The good news is this rifle using a 140 Berger VLD Hunter has done an amazing job the past 6 weeks taking down a 40" Gobi and an 43" Altai Ibex and a real heavy Alberta Mule Deer split real wide in his fronts and tall and split nice in the rears too.
Barrels throated a little deep for a VLD and with the neck I.D. working the brass like it is I may see if Melvin will put another barrel on it throated more friendly to the 140 VLD and with a neck I.D. of .314'. Kind of hate to mess with it though cause it shoots real well but annealing every second firing is a pain.

Dave

I have a 280 Ackley chambered by Melvin my fired cases measure .318 -.320 also....I always a thought that was a tad big for a 280.

Good information RT.

Thanks.

RaceTire,

Very interesting. Dunno why Melvin's reamer would have such a large neck, as SAAMI maximum for the .280 AI is only .315.

I wonder also !

I suspect he had before there was a SAAMI spec.

I'm sure he told me the chamber would be min spec SAAMI..when we did the order.

A smith just just clarified this for me .315 is the Max neck diameter for a loaded round..the actual SAAMI reamer is more like .3176.

RaceTire,

Thanks for the info. You cost me money. I just bought another bushing.

John,
When I was doing the research on the concentricity issue I stumbled onto all of the history of the 280 Ackley. As I remember (it's been a couple of months or more)there are a couple of chambers for a 280 Ackley. In fact when I ordered dies the first time I ordered what I thought were the dies I needed and they were not and of course I got 280 Remington 40 Degree dies. Cheap lesson ..!!
After I began trying to sort everything out and studying things I wondered about the SAAMI Spec and when it was developed thinking that for awhile there in fact was not a standard spec for this caliber and dimensions were (for lack of a better way to describe) at the discretion of the guy reaming the chamber.
Also, I have never tried to fire form anything as I have always used Nosler brass. My thoughts are that quite possibly the loaded neck O.D. of a fire formed round may be a little larger than the loaded neck O.D. of the Nosler 280 Ackley brass. (.311"-.312")
Ball micrometer measures neck wall at .0125" to .014" on the Nosler brass with most of it running under .001" difference.
Would like to emphasize again that my ULA 280 Ackley shoots very well and the fired brass that comes out of the gun when checked for concentricity they don't move the needle.

Dave