What is Runout? It sounds like something you don't want. So how do you controle it? Tell me about runout. Thanks in advance.

Runout is the deviation from the axial centerline of the bore. All reloading components (basically brass and bullets,)should center on the axial center of the bore line. Any deviation is runout.

You control it by having uniform brass and bullets to start. Then by sizing the brass and seating the bullets to maintain concentricity to that line. Good dies with a good marriage with the chamber to minimize sizing requirements and concentric seating of the bullet are a start. Then adjusting and using the dies properly becomes important.

All true, but you need something to evaluate your product. Sinclair and RCBS produce a variety of concentricity evaluation tools, from cheap(RCBS) to pricey. The RCBS Casemaster does a few other useful things as well, like measure neck wall thickness, and allow you to check for incipient case head separation. You may think life just ducky without getting involved with run out in your handloads, and if you're only interested in a few hundred yards and a deer rifle don't bother. It is required for successful long range work. Cockeyed bullets make cockeyed groups. If you do delve into this world, say to yourself before the fact, "I will not turn anal, I will not commit suicide, I will not wail and gnash my teeth in my dreams." It is educational, and sometimes frustrating. Correcting observed deficiencies requires analytical thought and patience. Good luck regardless.

Some people worry about it, other people don't. Me, I try to get rid of it in an attempt to make my loads shoot better. Don't actually *know* it will help.

If you do decide it is important, I second the opinion about having to get a measuring device. I have used the Sinclair "Concentricity Gauge" and find it easy to use.
- mike

JBM, do not got down this road. Don't say I didn't warn you. After you are done, you have 200+ dollars and 100 man hours invested in this. And all you will have accomplished is cutting down your flyers.

Last year I went down this path. I got concentricity guauges, sinclair neck turners, Redding competition seaters, and new shell holders to aim for this <2mil runout spec.

Now, I am stuck. And have to measure runout to satisfy my curiosity. Then I have to separate ammo marking the runout on the case. Its an infectious desease.

Managing runout is an investment of time and money I have found worthwhile. During the zzzzzzzzz... time waiting for my digital dispenser to finish a dump of powder I check the runout of the case I just loaded and sort it into two lots - Less than 1 thou and between 1 and 2 thou. About 10% are in the second class. These rounds are used for barrel warmers and sighting in.

I do not load a sized case with a jacketed bullet if it is over 2 thou. I check every case after sizing and if it is over 2 thou then it goes into a box where it is blown out again with a cast bullet. This happens seldom.

Knowing you are shooting with "good" ammo does wonders for your confidence.

The only cartridge I have not got quite sussed is my 22-250 but I am getting there.

OK. I think I will take bigcountry's advice and not measure runout. But I did want to know what it is, as I see posts about it. Now let me try to explain it. Is it the differance between the centerline of the bullet and the centerline of the bore when a cartidge is chambered? You can measure that? or do you measure the concentricity of the bullet to the case diameter? Can you measure the chamber to bore concentricity with these tools you mentioned? Does'nt neck sizing correct runout and put the bullet inline with the bore? Is'nt that why you neck size?

Reread what was written. You're getting into all the nuances of reloading and proper mating of cases and chamber.

If you neck size, theorically the case goes back into the chamber with a "glove" fit, unless the chamber is eggshaped. Some are. Presuming a perfect chamber and fireformed brass, well prepped and concentric, the brass is then concentric when chambered. If full sized, or even partially full sized, there may be some slop in the fit which may affect it sitting in the chamber concentrically.

Presume concentric brass with even neck walls, you still have the problem of seating the bullet straight. If the die functions well, it's all concentric. If it's not, or if there is variation in neck wall thickness, or if the brass is sized too much in one area providing more clearance, or . . .and on and on. For perfectly concentric cartridges EVERYTHING must me exact and perfect. Now, the big question. What difference does all this make? I happen to think it makes substantial difference. It has for me over the years yet I have friends who have NEVER checked it and can shoot tiny groups out of hunting rifles with their ammo and in some cases much better than my groups that ARE checked closely. The options are yours.