bullet run out on full sized cases

[Black Diamond 408]

This has problly been hashed over many times in the past but i was wondering what is acceptable for bullet run out in loaded rounds. .0001 .001 .002 I have never checked any of my loads and am building a test stand to do so. They all shoot very good so maybe i shouldn't test them!!!!
-out of sight, out of mind

Dave

 

[300win]

I have been measuring run out for years and I do believe it helps long range accuracy. Using quality brass and dies I can keep run out at around .002 or lower for 80% of my loaded rounds.

 

[Mysticplayer]

DON'T GO THERE /ubbthreads/images/graemlins/grin.gif

Was driving me insane but is helpful in diagnosing cranky rifles.

I check fired cases and sized cases. In almost all the rifles I own, runout is 0 to 2thou. That is excellent given that my guage has a tolerance of 1 thou error.

I use Lee Collet neck sizing dies whenever I can and cases show no change before and after sizing. No doughnuts either.

however, after seating the bullets, runout AT THE BULLET can increase. The neck/shoulder runout doesn't change though.

Crazy part is that even with runout varying (at the bullet) of one thou to 5 thou, groups are still very small. In fact, the smallest group one rifle ever shot was with the batch of highest bullet runout cases.

So I now keep track of case runout, and forget about the bullet runout unless I start to see problems on the paper.

Right now I am playing with my new 6.5 Mystic 1000mBR rifle. Runout for the cases are pretty much zip. Loaded rds show very low runout but a few cartridges can bump up to 4thou. Groups so far have been bugholes at 200yds using Lapua 139gr Scenars.

I am not going to worry about it anymore...


Jerry

 

[Black Diamond 408]

Thanks 300win and Jerry,
That is what i kinda thought about the whole thing. I just was going to check and see how accurate my custom dies are.

 

[goodgrouper]

I like to use the "zero's" for the maximum range shots but .001" usually will work ok too. Anything over .003" and I start tearing apart and analyzing my dies. If using regular old RCBS dies, .003 might be a keeper die but custom dies or comp dies are worth the extra money to get the extra .002" better concentricity imho. /ubbthreads/images/graemlins/wink.gif

 

[jeffbird]

fwiw - I kept trying to set and square my FL die and kept ending up with .002" runout on the case. The Zediker manual had a fix which worked for me. Replace the metal wire which compresses the shellholder with a rubber O-ring ($3.49 for a mixed pack at the auto parts store). The shellholder sort of free floats just a bit and dropped my runout (from that source) to near zero.

 

[jmden]

...or just use the shellholder without anything holding it in place with shellholder/ram bearing surfaces clean with a little very light lube on the bearing surfaces.

 

[Bart B]

I get the least bullet runout when cases are full length sized in dies having their necks lapped out about .002-inch smaller than loaded round neck diameter. This sizes the fired case neck only down and the neck isn't bent when the case is pulled out of the die cause there's no expander ball.

Bullets tend to align themselves to the neck axis when seated. Cases so sized as above can have bullets seated with just about anything and get runouts less than .002-inch. Depending on how the runout measuring tool is set up, one can get a .002-inch spread across them. There is no industry standard in bullet runout measuring tools.

If bullets are seated out to touch the lands when chambered, even .003 or .004 inch runout rounds will shoot very well indeed.