Hey there Jim. I've been wondering and experimenting with concentricity in my hand loads. None of my tests are real complete, but I'll share with you my observations. If your looking for a set of dies that will load them perfectly straight I haven't found it yet. RCBS and Hornady seem to work about the same the Lee dies didn't work as well in my experience. In lee's defense all of my Lee dies are the cheapest ones they offer.
I've noticed different brands and shapes of bullets can vary drastically in the loaded round runout department. With my 30-06 I've tried Lee and Hornady dies with several different types of 180 Gr. bullets. None of them were consistant. Some were pertectly straight, some were over .010" off center and any amount in between. I've yet to load a decent 30-06 I'm happy with. I did switch shell holders and had much better results (.005" runout or less). Before I switched I loaded all calibers with that head size with that shell holder and none of them were straight. Now I wonder if it was the shell holder all along.
In my 25 WSM wildcat using RCBS dies I've managed to get pretty good results by picking a spot on the case head, (the letters WSM) and size the case once with WSM towards me then rotate 180 degrees then size it again. That has got me the straightest cases. I do the same thing when I seat the bullets. Most of them come out with .002" runout or less. All of that seems to point to a alignment issue in the press or the dies. If I orientate the cases in the press using the WSM, the loaded rounds always come out with the runout tilting the same way with relation to the WSM on the case head. All my 25 WSM cases were neck turned for uniformity.
I've tried to straighten rounds with some success but it takes forever. So far the best way I've tried is to find the direction of the runout and then take an old fired case and slide it over the bullet and pry it in the opposite direction of the runout. It takes a lot of trial and error and in my oppinion is not really worth the time. There's a company that I think is called Bersin that builds a tool that measures runout then allows you to straighten the bullet, but they are pretty proud of them price wise and I haven't felt that rich yet.
BTW my runout tool is made by RCBS I think it's called the casemaster. I've only used the dies I mentioned above. My press is RCBS Rockchucker
I sorted 30-06 loads by runout in batches and fired them for groups once. I had .000" to .002" then .003" to .005" and so on and so forth until I had a .010" and up group. The .010" and up group shot a 3.5" group, roughly, at 100 yards. The .000" to .002" group shot into about 1.25". Another interesting test I've done with the 25 WSM since it's a Ruger #1 single shot is find the dirrection of the runout and mark the case head with permanent marker. Then wene I load the gun I always put the mark pointing up. My theory there is, even if the bullets do have some runout at least they will enter the throat and rifling at roughly the same angle. If you have two bullets and they both have .002" runout and one enters the chamber with the runout pointing up and the other pointing down, you now have a .004" difference. Loading the single shot like this has also improved my groups.
I hope this all makes sense, and I didn't ramble on too much. Anyone with other experiences and ideas please let me know. If you feel I've wasted too much time on all this, feel free to let me know that too.
Let me add some more (and probably add confusion).
Concentricity--and concentricity gauges. The perfect tool perfectly designed to drive reloading nuts--NUTS! I have two of 'em, this way I can double my agony--er, pleasure. One is the old style Sinclair V-block and the other is the new style Sinclair "ball bearing" gauge.
Don't get me wrong, concentricity of our loaded rounds is indeed important. John Barsness has an excellent article on this subject:
Having said that, I think there is one of those "obsessive" reloader trends developing over concentricity.
A couple of years ago, I used a custom barreled .270 (it likes most bullets and loads I put through it). With Sierra MK's, I shot one batch of loads with bullet and neck runout held to .002 and under, the other batch with runout between .003-.004. 10 shot groups, and I tried it two times under different conditions. I could not tell the difference in my group sizes. (Although the extreme spread of the batch held to .002 was about 15fps less than the other batch).
Here is my idea why, in the context of hunting rifles and hunting cartridges; With chambers reamed to standard dimensions (regardless if it's factory barrels or custom barrels) they are designed to accept a variety of different manufacturers cartridges and work under a variety of field conditions. In other words, a chamber is intentionally "sloppy". It must be sloppy in order to function with powder carbon, dirt, pine needles, dead squirrels, etc, etc, finding its way into the chamber and with slightly different cartridge dimensions.
When a round is chambered, there is enough space between the case (including the neck) and the chamber walls for gravity to take over--ie, the round lays in the BOTTOM of the chamber. When we talk about concentricity, we are not only concerned about starting the bullet straight (as John Barsness points out), but we also must think about if the center axis of the bullet is aligned with the center axis of the bore. When the round is laying in the BOTTOM of the chamber this won't happen--regardless if the concentricity is perfect (.0000)--because the axis of the bullet is BELOW the axis of the bore.
I hold my loaded rounds around .004 in my mid-bore cartridges. Smaller bore rounds to around .003. ( I know this will be treated as blasphemy).
I own 27 sets of dies (including 6 sets of dies for the same cartridge--sheesh). I think the S Bushing dies from Redding have the potential to size dies "straighter" than othe dies (I own one set). I also like Forster seater dies the best. I notice Mr. Barsness talks about the Competition S Bushing dies--they are very expensive--the regular S Bushing dies will work just fine for anything other than a Benchrest rifle.
Lube the inside of your necks, this helps the button pull through easier. I use Imperial Sizing Die Wax. Clean the lube off the case--inside and out! I use a parts bucket with lacquer thinner.
