[SquirrelNuts]

I was watching this Ammosmith video, and he keeps referring to "run out" with his dies. What does that mean?

http://www.youtube.com/watch?v=Xc1lDG9E_UI

[rcmodel]

Probably refering to how straight, or how crooked, the finished ammo is.

Ideally, a loaded round would be perfectly straight, with no measurable run-out or wobble of the bullet when rolled on a table, or measured with a dial indicator.

Unfortunately, that is often not the case.

rc

[USSR]

Basically, the straightness of the neck in relation to the body. When using an expander ball, it is quite easy for the neck to get "pulled" to one side so that it is no longer perfectly in line with the body. That's why I won't use them.

Don

[Walkalong]

Yep.

You can measure it with various devices. This NECO is one. If you are not target shooting, it's not that big a deal, unless it's way off. If you roll it across a flat surface (I mean really flat), and you can't see any wobble, you are good to go except for the more demanding shooting.

http://www.thehighroad.org/attachment.php?attachmentid=96450&d=1240061816

[freakshow10mm]

Runout is a measure of how straight a bullet is to the direct center of a cartridge. I measure mine with an RCBS unit. Everything .003" or above gets put in the "plinker" pile. Everything with .000"-.002" runout are keepers. I test both my handloads and my commercial loads for runout.

[Larry Burchfield]

runout is measured like the other posts say but it is controled by your loading dies both the sizer and the seating die. If you neck size you should use a benchrest neck sizing like forrester and they also make a seater die that works well (I use these type dies). But if you really want to do good you need to use straight line dies and an arbor press.
Just remember that if the bullet doesn't start straight it won't shoot straight.
Larry Burchfield
SEABEES/RVN/67/68/69
DAV

[Martyk]

Run out is the amount of deviation around a rotational axis. For example, if you draw an imaginary line directly through the center of a circle, the distance from the centerline to any point on the circle will be exactly the same. This scenario has no Run Out. If the circle were to be shifted off (but the centerline stayed in the same place), then you have varying distances from the centerline to various points on the circle. This scenario would have run out. The term means that the circle is running out of concentricity to it's center (or Axis).

When you make a bullet, the more concentric everything is, the better accuracy you will be able to achieve.

[lgbloader]

I measure mine with an RCBS unit.

I could not live without mine. I guess there are others but I really like this one.

LGB

[Shoney]

Trying not to beat a dead horse, however, "What is run-out?" or as it is more correctly called concentricity. As shooters have become more demanding in their search for accuracy, specialized reloading equipment has come into the market. It is well known that bullet run-out, or concentricity, is a major factor in producing accu-rate ammunition.

In the good old days, when men were made of iron and boxcars were made of wood - - Sorry, I couldn't resist:evil:; the accepted practice for checking concentricity was to roll the cartridge across a flat surface, such as glass, and note any wobble at the bullet’s tip. This was a fast way of culling obviously defective cartridges, but will fail to isolate those with less obvious run-out problems. Besides improperly seated bullets, the case itself can be defective, i.e. the wall thickness of the neck varies from thin on one side to thick on the other. The limitations of the rolling approach become unacceptable.

Today, handloaders have several options that are capable of measuring concentricity to .001" or less. Most operate on some variation of the same principle. A loaded cartridge is mounted in the unit, normally supported by a “V” block arrangement at the case head and bullet ogive (good picture above). The cartridge is rotated slowly, while a dial indicator bears on the area of the cartridge being checked. Any concentricity problems are not only immediately visible, but measurable on the dial indicator.

One of the first commercial models, which is still readily available and quite popular, was the Forster/Bonanza Co-Ax Indicator. Recent entries in the concentricity gauge market include models by Sinclair International, NECO, and RCBS. Some models, such as the NECO Gauge and RCBS Case Master, are capable of not only measuring bullet run-out, but case neck variation, wall thickness and concentricity as well.

[freakshow10mm]

I love my RCBS station. I picked it up about 4 years ago at a gun show new in the box factory sealed for $25. I also snagged a set of Redding .375 H&H dies for $7.50, factory sealed. I would be a fool to pass up those deals.