Originally Posted by Forester
I have all of a sudden developed a problem with high runout in my reloads. I used to get very consistant .003" or less with many coming in at .001" or so.
Nothing has changed as far as brass or preparation goes. My cases have .001" or less after they are fully prepped but when I seat a bullet it comes out with .006"-.007" runout. I usually use a Redding competition seater die and I have also tried a standard Redding seater die with the same results.
The press is a Forster Co-Ax and is fairly new and in good shape. I cleaned up the dies well as well as the press, and nothing seems to help.
Anyone have any suggestions about what else to look at? I am out of ideas except to try another press in case something has gotten tweaked about mine.
Before it is even said, I have proven to my satisfaction that runout over .002" does matter, and it matters more the longer the shot.
.001-.003 suddenly jumping to .006-.007 is pretty significant, over a 100% increase.
Brass, like almost all metals has a certain degree of spring to it, it has to otherwise it'd never come out of the chamber after firing it. So, your brass has to be "influenced" more than just .007" for it to have a TIR of .007" I'd say on a guess its probably more along the lines of .015 or .020. Just a guess, I don't have any real way of knowing.
So, where in the operation of loading a case is sufficient force generated to cause this much defelction? I'd say two; sizing and bullet seating.
You stated that the case looks pretty good once its all prepped. That it isn't until after the bullet is seated that things get goofy. Here's where I'd focus the attention then.
This also eliminates the press I think because the problem should have surfaced during sizing as well.
Back to seating. I guess make sure the shoulder isn't banging into the die. use some prussian blue high spot indicator on the case shoulder and see what's going on. Make sure your case mouths are chamfered, especially if using a flat base bullet. Make sure seating depth isn't so great that its crushing (crunching) powder and causing you to use excessive force when seating the bullet. Make sure you have the right neck sizing bushing (if your using one) in your sizing die and that you are not overworking your brass and causing a partial shoulder collapse when seating the bullet from excessive neck tension.
This is where I'd focus my attention.
Thats kind of the problem with these bullet/case runout gagues, they tell you something is up, but don't really show you where.
Do you use a neck mandrel? Sinclair International sells a nice set up that will straighten necks on new brass. I do this on all my cases prior to loading since its so easy to ding a case mouth and cause it to go out of round. Might look into one, they don't cost too much and you can buy (or make) arbors for different calibers. Very handy tool.