Bullet runout

N

noone

Guest
For quite some time, I have been sorting my reloaded ammo by the amount of runout the rounds have. I group them into anything having 0 to .0015, .0015 to .0025, .0025 to .0035, .0035 to .0045, and anything (if there are any) over .0045.

Then I got into a rather heated discussion with another reloader whose contention was that I should group them into anything with .0030 and less, and .0030 and over. His contention was that you can't tell the difference on rounds with less than .003 runout, and over that should all be practice rounds. I have found that I do have better accuracy with rounds having .0015 runout and less..

What have other reloaders here found? Is my experience unique, am I being too picky, does it matter? What categories are you all using when sorting runout?

Sorry for not specifying..the runout is in thousandths of an inch, not metric.
 
Noone

In Benchrest, or any other extreme accuracy discipline, we strive to machine chambers to where everything is within "tenths", and not many of them. So, logic would dictate that the ammunition should be equal in it's precision.

But, is .001 runnout on a loaded round the same as a chamber being .001, (a lot in precision barrel work), miss-aligned with the rest of the barrel.

In all honesty, I don't know. I have shot phenominolly small 10 shot groups out of my Rail Gun with rounds that ran out as much as .002. I have also seen shooters shhot really good aggs with rounds that we knew were not that straight.

.003 seems a tad extreme for extreme accuracy work, or at least it would seem that way.

One thing you need to address is why you are getting such an extreme spread in the runnout of your rounds. I believe that, contrary to what many think, most runnout is induced in the sizing operation, not the seater. If the case comes out of the sizing die in less than a striaght condition, the seater probably will not starighten it out.

The way I get my rounds to run straight is I finally went to a solid one piece sizing die, that has no bushing. That does lock me into one neck tension, but I can tune with seating depth, the powder charge, and of course, the tuner..........jackie
 
noone said:
For quite some time, I have been sorting my reloaded ammo by the amount of runout the rounds have. I group them into anything having 0 to .0015, .0015 to .0025, .0025 to .0035, .0035 to .0045, and anything (if there are any) over .0045.

Then I got into a rather heated discussion with another reloader whose contention was that I should group them into anything with .0030 and less, and .0030 and over. His contention was that you can't tell the difference on rounds with less than .003 runout, and over that should all be practice rounds. I have found that I do have better accuracy with rounds having .0015 runout and less..

What have other reloaders here found? Is my experience unique, am I being too picky, does it matter? What categories are you all using when sorting runout?

Sorry for not specifying..the runout is in thousandths of an inch, not metric.
Click to expand...



In my opinion, worrying about loaded round runout is a waste of time. Here, I'm talking about 22 and 6mm cartridges used in short-range benchrest.

Most shooters will have at least .001 to .002 TIR in their loaded rounds. I'm sure up to .003 has no effect on accuracy. What DOES matter is neck tension and seating depth.

Gene Beggs
 
I have also seperated mine by runout for use at 500 yds. and farther, anything 300 yds. and under I'm not as picky, depending on which Range is hosting the Match. If it's a walk and paste 300 yd. Match all the rounds ( 5 sighters & 45 for Record + a few incase)are the same ( usually around .0005-.001) due to not being able to tell what your group is doing untill it's time to score, 15 rounds in 15 mins. with no pits. I have used the Bersin Tool with some interesting results, mostly good, but you must never....or at least I'll never try to push them more than once.
 
I also have had runout in my match ammo after recently spinning for runout found some to be out as far as .015 T.I.R. . I tried everything to correct the problem with no success. i deemed anything under .004 tho.a good round . Problem solved when i put the custom dies on the shelf and made my own bushing sizing/ seater die up. What ever dies you are using i suggest you try something else. Bushing dies will work if they are made correctly. i built a bushing die for ease of achieving different neck tensions . The Rifler
 
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I don't compete but still strive for sub 1/2" groups and get frustrated if I can't get them. So, I'm fussy with my hand loads. Like you, I also sort my rounds in a box according to their concentricity reading.

For a test, I once purposely witheld cartriges that were off 9,000ths VS cartridges I had been firing that were say only 4,000ths off or less. I saved those accentric cartridges for the final shots 6th or 7th shot of the 4 or 5 shots I already fired. I'd fire them to the target just like the prevoius 4 or 5 rounds that were grouping 3/8" so far. Lo and beheld, they would open the group! (perhaps to 1/2") I can't tell if it just happens to be human error with "pulling the last shot" as sometimes we do, or it was legitimate testing results. But now only I feel comfortable saving those kind of rounds for "foulers" or "sight-in" rather then for precision shooting.

As for what I deem acceptable: I consider anything on my Sinclair gage that gives me readings of "4,000ths" or less as excellent rounds for the finest target groups. 5000ths is acceptable, and 6,000ths and up is saved for less serious work. (with 9,000ths as "junk")
 
Runout and groups

I came up with this 'brilliant' idea a few years ago about indexing some rounds and loading them all in the same direction and then rotating the next group 90 degrees, etc. The point of impact changed in the direction I rotated the cartridges. So I did some reading and found out others had been there and done that and reached the same conclusion. A day late and a dollar short again, but getting there is half the fun. nhk
 
I had purchased a Forster bench rest seater die, Redding one piece sizer die. I returned the seater die, as after measuring cases coming out of the sizer, I suspected the seater die. Forster replaced the bullet seater stem and said it was bent..

I bought the die from a company on line as they had one out of a set. My guess is that they had one out of a set put aside to return for repairs, and someone forgot that it was to be returned, not sold. In any case, Forster returned it REALLY fast, and now it works much better.

I'm still striving to get the same low runout that I get with my 308 and 300 win mag. So, I outside neck turned about 150 cases, and will fire form them, then try again.

After getting the die back with a straight stem, almost all of the rounds with .004 or .005 runout were gone. Out of 154 rounds loaded after the die came back with a straight stem, only 2 had runout of more than .004. (One had .005, one had .004)
 
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