concentricity guage

[cclawman]

What would be acceptable bullet run out?

 

[Anmlsrdelicious]

Depends on what you are going to be shooting. Short range BR matches, or the longer stuff like 600 or 1000? I shoot 100 and 200 BR, I keep my runout at or under .001 I have heard up to .003 is acceptable, but my dies spit them out at .001 or under, and I am happy I don't have to worry about it. I'm sure some of the long range shooters will chime in with what thier acceptable numbers are.

 

[JamesnTN]

.001 runout equates to near 3" at 1000 yds so if you have say .002 runout your groups are 6" there abouts before anything else is involved. My match rnds have "0" runout and I check everyone.

 

[chuckw2]

James,
How do you measure run out and which tool do you recommend.
If a round had say .005 run out can it be corrected with a Berson tool, do they work?

Chuck

 

[Caduceus]

.001 runout equates to near 3" at 1000 yds so if you have say .002 runout your groups are 6" there abouts before anything else is involved. My match rnds have "0" runout and I check everyone.

James,

Are you saying there is a proven linear correlation between runout of loaded rounds and group size?

While I'd agree that every effort to produce identical loaded rounds is conducive to shooting small groups, I have my doubts that the relationship is as linear as you describe.

I'd like to hear more about this.

 

[JamesnTN]

James,
How do you measure run out and which tool do you recommend.
If a round had say .005 run out can it be corrected with a Berson tool, do they work?

Chuck

Chuck,

I built my own guage from a sine plate V blocks and a .0001 indicator. I have a brand new Neco guage but I have never used it seems my home built contraption works well enough and it's a bit more stable, probably weighs 25 lbs. The Bersin tool is another well used device on alinging your bullets however I don't recommend it as one needs to find the root cause and fix runout from that angle.

For correlation on 3" per .001 runout I have not tested this at 1000 yds but I have tested it at 300 yds and when I had my 500 yd range I tested it at 500 as well. From my testing the 3" is pretty dang close as i shot rnds at 300 and 500 and took same loads with runout and bullets shot out of the groups by as much as 1.5" at 500 yds and this test was done at dawn with no wind and or mirage and was done using a 125 lb 300 ackley setup on a solid bench and proper rests and the down range accoustics showed impact changes of 1.5" for .001 3.1" for .002 and .003 runout was near 7" for the one flyer and the same brass was used on ea shot and bullets sorted and spun. Again no elements of wind was involved and no gun handling just touched off the trigger. Temp was 78 deg humidity was 40% and velocity of a 220 grn bullet was 3115 fps all this run thru an Oehler model 43 and using a davis weather station for data input on atmosphere conditions at ea range of 100 yds from the range house to 500 yds.

 

[Caduceus]

Thanks James, that was just the kind of info I was asking about. Very interesting.

 

[StephenPerry]

Chuck
Lester Bruno has a nice concentricity gauge that check you lineup with the bullet in the case. You can correct to less than .0005. I have one. Lester has used his for the last 15 years. You can check and correct, if needed, 20 loaded cases, in 5 minutes or less. Call Lester. Works for most cases.
Stephen Perry