I was having some trouble getting straight cartridges when loading for my new 300 RUM. Many of my loads had visible runout when rolled on a flat surface. I wasn't even checking for runout, I just happen to notice it when one rolled on the kitchen counter. Some were quite bad and some had no visible runout but most of them had some.

I suspected it was the new Remington brass so today I decided to see what I could find out.

I took a fired case and FLR'd with no expander ball in the die, then I used a neck expander that came with my neck turning tool and the neck was turned to about 50% cleanup or a little more. I then partially full length resized the case as I had been doing all along and seated a bullet. I still had visible runout but not as much. Next I pulled the bullet and FLR'd again with no expander and seated a bullet. This looked perfect to the naked eye. (I don't have a case measuring tool).

Next I tried just FLR with no expander and no neck turning on another fired case and still had a detectable amount of runout.

The only way I could get no visible runout was by neck turning and FLR with no expander.

I was surprised that PLFR'ing with an FLR die was causing runout as I've been doing this for years with other calibers. Maybe its not all its cracked up to be.

I believe I'll get a Lee Collet die and see what that does. The above dies used were Lee as well.(new)

Has anybody got an idea why PFLR'ing would cause runout? Or perhaps FLRing is eliminating runout...

Discuss.


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Try it one more time with the expander/decapper loose, so it might center itself. I've heard it can help, and tried it, but I never noticed runout to begin with. Let us know if it makes any difference.

I can't come to understand PFLR.....I would call it 95% FLR...or more. If you are barely working the brass you wouldn't need lube on the cases....how many are doing it without lube??

Here is how to eliminate runnout from most standard dies.....it's worked well for me on a couple dozen sets.....

My $.02 worth---ALL dies with expander balls need tuning. Think about it...a piece of typing paper is .003" thick--what are the odds that the expander is not PERFECTLY centered in a die and could pull a case slightly off center??? Pretty good I'd say. Pull the expander stem out of the die (and now is a good time to clean the inside of the die). Run about 5 brass into the die and see if they come out concentric. If they do (and usually they will) you now have to try and get that stem centered on re-assembly. A great way that helps is to put a piece of very concentric brass up into the die to hold the stem in place as you tighten it down. Sometimes this takes 2 people unless you have 3 or 4 hands. AFter reassembly try sizing some brass and check runnout. If not good then do very small turns of the expander stem--probably 1/32 of a turn at a time. Resize some brass and repeat the small turns. At some point I can almost guarantee that you will get GREAT RUNNOUT CONSISTANTLY. (Somehow, someway the expander spindle will hit almost perfect centering in the die body) I have many dies that consistantly make less than .002" runnout after sizing with most of the brass at .001" and less. I own, hornady, redding, forester, rcbs, and lee dies. ALL OF THEM HAVE BEEN TUNED and most make fantastic ammo and all make good ammo!! I have never ever got a set of dies from any factory that made as good of ammo as those that I have done this simple work with.

Your size die squeezes the necks too much and when you expand by any method, the shoulder bends. Almost all runout is caused by sizing and expanding, not seating. Get the Redding size die with the collars and just size the amount needed to seat a bullet without needing to expand.

And for what it's worth I can't be convinced that just "sizing a bit so the bolt has a little tension when closing" is a good idea either. I've proved to myself (in my guns) that this can cause a 4" point of impact change at 100 yds over brass that has been reduced just enough so that IT DOES FIT PROPERLY in the chamber WITHOUT tension to close the bolt.
Just my opinion and experience.....not the kind of fit I want hunting in the field either.....your mileage may vary!!! Good sizing.....GOOD SHOOTING.

Kraky, that is also correct. Too much pressure closing the bolt on a case can also bend the shoulder causing runout. The headspace portion should just make even contact.

Thanks for your replies. They all make sense to me.

However, this was all done with no expander whatsoever. I removed that first when I noticed the runout.

So, with no expander at all I'm getting runout when PFLR and no runout when FLR, with partially turned necks in both cases. I wonder why?

Seating force with no expander used was higher than normal but in no way excessive. Boat tail bullets helped here. Seating force decreased noticably after neck turning, as would be expected in this situation. I doubt if there is enough force while seating the bullet to deform the shoulder. Its nowhere near as much force as is required to pull an expander up through. If seating force were causing the runout then I think the FLR case with the whole neck resized would generate more force and cause more runout. The opposite is what happens.

Keep in mind too that I'm just eyeballing these cartridges for runout. A case measuring tool is in my future.

Also, the Lee type expander held by a collet can't be left loose to self center. I suppose it could be turned in tiny increments but I suspect that each time it was loosened and tightened things would move around in relation to each other and turning it a tiny increment would be of no value. I may be wrong here however. Anyway, the expander is not in use here.

Any more ideas as to what is going on here?
Trying not to bore everyone to death but this one has me stumped. I think runout may be more noticable on such a long cartridge too.

Runnout is definately more noticeable on longer cartridges. Re tuning the expander....keep trying to loosen and retighten until it hits dead center or as good as possible. I have quite a few sets of early hornady dies and that's what I had to do and finally they tightened down centered. Again..if you can get them a little snug and then raise a piece of brass up to the expander and then tighten it seems to help. I do this using a knee on the handle and a deep well socket. (If the wife saw me she'd think I'm finally making love to my reloading equipment!). It's been my experience that any case mouths that are tighter than .003" grip will give more runnout when seating. Another "trick" that seems to help and may be a factor with the sizing situation is to take your index finger and hold the casing tight to the back of the shellholder as it's entering the sizing die....especially with the lee shell holders with their big "ramp" into the holder.