Bullet Runout In Oal

[Little Bill]

I found an old thread while searching for some insight to a problem that I had, and I bumped it back to the top. I began wondering about a few other things, so I decided to start a new thread.

My original problem was that I noticed that some new loads I was trying had a one-in-fifty case gauge failure because the bullet had too much run out. (You can see it if you roll a bullet on very flat surface, looking from the side)

I am loading 9mm 115 Zero JHPs at 1.150. The bullet's OAL is .525, and my calculation says that I am seating the bullet about .120 deep. When I was loading 147 JHPs at 1.150, I did not see the same problem, but they are seated much deeper. I am using a Dillon 650 with Dillion dies, except for a Lee "U" sizing die. I also noticed that if I pay very close attention to the bullet concentricity while placing it on the loaded round, it has very little run-out. If I pay less attention, the runout becomes greater.

I would like to keep this load at this length (if possible), and I was wondering if anyone has any ideas or input. (I was thinking about the Redding die http://www.redding-reloading.com/pages/comphandseatdie.html )

That leads me to my current wonderings....

How do you measure runout? (bullet wobble)

What is the maximum acceptable amount of runout?

How much does runout effect accuracy?

Thanks for the input!

Bill

[ErikW]

Hold on a minute....

An out-of-round bullet with a lot of runout would be a problem, but you seem to be talking about something else, cartridge runout. You are concerned about the bullet not being concentric with the case?

[Little Bill]

I think that I am poorly describing the problem.

When the finished round comes out of the 650, I can take to a very flat, level tool bench and roll it on its side. If I look at it from table level, you can see the bullet "wobble". The brass appears to be rolling normal, but it APPEARS that the bullet is seated "crooked" in the case. Clear as mud?

Not all of the rounds have this issue. Some, if not most, appear to roll very well with little "wobble".

If, while reloading, I concentrate on bullet position while placing the bullet on the powder loaded/primered brass, the problem appears to go away.

Does that help Erik?

So, I am trying to figure out the "wobble" issue / measurement.

[John Dunn]

Sinclair International carries a device to measure runout, but I've never seen it done for pistol ammo. I'd just relegate the stuff that fails the gauge to practice, and not sweat measuring the ammo like the benchresters.

[ErikW]

OK, I'm with you now. What you are describing is especially noticeable with certain combinations of brass and die when you get a cartridge with a thicker top (where the bullet is) tapering down to a thinner waist. (It is very noticable in 9mm.) I think a post by Nolan somewhere explains why this is desirable. As you turn the cartridge to examine it, the waist effect is not always uniform around the cartridge. Like John Dunn said, I don't worry about it.

However, I would worry about a 1-in-50 gauge failure. Are you sure it's not the brass? (Take some failed cartridges, impact-pull the bullets, and gauge the cases.)

If the bullet really isn't seated concentric with the case, then I would blame your reloading press for not having the shell plate index perfectly with the die. Even then, I would expect it to self-center as long as it had a little play.

Edited January 12, 2004 by Erik Warren

[eric nielsen]

It's good that you notice the sort of things you found, but I think you're all right.

Almost all of my brass with more than 2 firings on it shows a side that is sized down tighter than the opposite side. I think its due to both the chamber/extractor combo in the gun, and the sizing die/shellplate combo in the press.

If your barrel has any amount of freebore at all, even just the normal ramp-type of taper into the lands of the rifling, then I'd say you're fine. Nothing to really worry about.

Course it doesn't hurt to be curious, and maybe even prove us wrong.

You could separate loaded rounds by whether they're nice & concentric, or not, and compare group size for 4 or 5 shot groups. IF you're good at shooting groups, and calling your own flyers. Never hurts to work on it, either way.

I *would* worry about chamber check failures in the actual barrel you shoot from. Those rounds are a problem.

[Little Bill]

Thanks fellas. I will keep my "wobbly" rounds to the side, and when I do some group shooting next time out, I will see if I can tell the difference. I was using head-stamp sorted brass that was some older Win +P+, and I wonder if that may have been a compounding factor. Keep ya posted...

[.40AET]

Bill- You mentioned that you are using a Lee "U" die for resizing. That die is likely your problem. Although I don't understand bullet runout, I had the same problem that you described in the second message. I switched to the standard Lee die and the first thing that I noticed was that the bullets "looked" a lot better. Curiosly, the bullets also gauge better now. I also get a lot of Glock brass and the standard die doesn't seem to be having any problems resizing the guppy bellies.

Good luck,

Kirk

[davecutts]

I'm also thinking the U die is the culprit. I'm useing one too, and I think when the brass is undersized you seat a bullet the weakest portion of the brass is going to give first resulting in the bulge being more noticable on one side of the loaded round. Actualy Mike Voigt and I were talking about my major 9x19 loads and he wanted to know how I was sizing the brass so much, and said the bullets not being straight in the case would be detrimental to thier accuracy. He was saying that most die makers make thier 9mm dies just like a straight walled dies, with a small carbide insert. So I'm on a mission to find a 9mm die that sizes the entire case with the proper factory taper, he suggested rcbs and I have one on the way.

[davecutts]

well I tried the rcbs die and I am not all that happy. I got an older die off ebay and the carbide ring is not tapered, ie the entrance to the die is a 90 degree angle, and one out of twenty cases would catch on the lip. Anyone want a good deal on a lightly used rcbs 9mm sizing die. I'm going back to my lee "u" die and a redding comp seating die, which seams to solve the runout problem.

[tightloop]

I'm with John Dunn on this one.

You will get some misaligned bullets if you load shorter bullets or increase the OAL to the point that the case doesn't hold the bullet the same (as deeply) as when you loaded longer bullets. This is more apparent in more than once fired brass, as the case neck tension lessens with more firings and the bullet seeks the point of least resistence as it is seated, thus the off center or wobbly bullet in the case.

Good case neck tension is very important if you are to have accurate loads, as the bullet pull will differ on each round causing high SD and poor consistency in velocity, shot to shot; even if the accuracy is adequate.

Again John nailed it, I don't think there is need to purchase the run out indicator from Sinclair unless you want to apply the bench rest techniques to each pistol round you load.

[Little Bill]

Thanks for all of the replies. (ahhh...a drink from the fountain of knowledge)

TL- I am with you and John too. I never planned on buying a run-out gauge, I was only hoping to improve my ratio of good-to-bad, and trying to understand how "bad" is bad.

I think that I may try a Redding die as soon as pocket book recovers from the Open gun purchase and see if that helps. I have been getting 1xfired brass, and not loading it a second time, and I think that I will start headstamp sorting to try and improve on my SD / accuracy in conjunction with the Redding.