Importance of different bullet lots??

[T-shooter]

Are those averages or just one bullet from each lot?

It was just one bullet for the complete measure but I went through maybe 20 of each lot to see what the size range was and picked ones based on the average overall length. I remember the average overall length varied .010" to .015" between the different lots. With any brand it would be wise to buy in at least lots of 500 to work up your loads with. I have seen differences in roundness of up to 0.0003" in Hornady, Sierra and Berger premium bullets. I think I read someplace that Berger says that is within normal tolerance. I use the Hornady tool to measure each seating depth to within .001", never from the tips. (my Hornady tool bore measures .298" for a .308) Even with that, one of these bullets would sit .038" deeper into the case reducing it's internal volume and will change the pressure to some degree when fired. The same with cases. I got a lot of Hornady match cases that averaged 7% more internal volume even after firing once. I have never checked Lapua. There was a noticeable drop in velocity (and accuracy with my loads) with the larger cases.

 

[T-shooter]

View attachment 1092137

You usually dont even need a comparator. Yours are pretty good i’d say. (Picture stolen from here way back)

Don't need a caliper or a mic with those, just a tape measure. Are those all from the same box?

 

[powderbrake]

I have found a significant difference in velocity and in the location it strikes the target at 100 yards between different lots of the same part number bullet. By significant I mean a change from a group in the .1's or .2's to something like .4 or .5. I believe this is primarily due to the shift in the location of the ogive and the location of the seating stem touch point.

I treat a new lot number like a whole new load, I do powder and seating depth tests of each lot number. I have learned to buy bullets in larger quantities, like 1000.

 

[dcali]

View attachment 1092137

You usually dont even need a comparator. Yours are pretty good i’d say. (Picture stolen from here way back)

I wonder what the variance in base to ogive is for those. Would be interesting to find out.

 

[Dusty Stevens]

Don't need a caliper or a mic with those, just a tape measure. Are those all from the same box?

Yes sir. A member posted them here a while back. Cant remember who it was.

 

[holstil]

I suspect if lot numbers didn't matter there wouldn't be any. Something or things are changed. Tools, material or personnel.

 

[Ned Ludd]

View attachment 1092137

You usually dont even need a comparator. Yours are pretty good i’d say. (Picture stolen from here way back)

These bullets are obviously from the Seating Depth Test Lot. You sort them into OAL by eye, find out which length group exhibits optimized seating depth and grouping, then order more of just that length.