Bearing surface length change between lots

[sgt_jamez]

I just recently started trying to sort bullets by bearing surface length. I’m using the Sinclair bullet sorting stand with the .243 comparator. I’ve noticed this issue with other brands of bullets, but I’ll limit this to the Hornady 6mm 105gr BTHP Match bullet. I bought two boxes yesterday and they are from different lots. I can provide the lot numbers if anyone cares. I measured 50 from the first batch and found them to have a median bearing surface length of .562”. Ok fine. So I started measuring the second box and immediately noticed the second lot was longer. After measuring 10 (all I had time for this morning) I found they had a bearing surface length of .596”. A difference of .034”.

So my question is if it is usual for “match” bullets to exhibit .030”+ shift in bearing surface length from one lot to another?

Additionally, since the bullet base would shift .034”... and essentially changing the case volume and start pressure... is this a difference noticeable on paper?

Im running a 6mm BR and my most consistent loads are averaging .253 MoA (my last long ad was using a 105gr Berger and the new lot of Bergers are of a different BSL than the bullets shooting the .253 groups.)

Is this something to be concerned about or a non-issue?

Thanks for reading!

[LoneWolf]

Hornady and Nosler seem to be the worse. Bullets get processed on difference machines etc. Berger and Sierra are better, but you'll still see differences. Have heard reports that JLK's are the most consistent guys have ever seen.

[yobuck]

For as long as i can remember, the bench rest shooters ive known have been sorting bullets of match quality.
That said they were also carefull about sorting the cases they use, and as a rule used the same few cases over and over.
Today, many of them seem to have switched to custom made bullets.

[cowtownup]

The "Sorting bullet" road is a long and winding one...

[243LPR]

Ive seen quite a difference in Bergers also.

[Zero333]

This is normal. Always take new measurements every new box even if lot # is the same. Usually (most of the time) once you find the proper seating depth (in relation to the lands) it should hold true for different lot numbers as well. There are always exceptions so beware.

If the 105 Hornady BTHP shoot best in your barrel jumping 0.030" then other lot #'s of same bullet should too.

Thus having to take new measurements every new box and re-adjusting the seating die if necessary.

[Stumpkiller]

I have been shooting the Sierra #1410 52 gr HPBT MK since 1976 to present.

Like anything else manufactured there will be batches produced on equipment that has a service life and gradually wears, so tolerances and replacement parts introduce variances. But I have to say that bullet has been VERY consistent in my experience. Granted, it's tiny and variances would be small. ;-)

When I went to .264" I started right off with the 142 gr Sierra MatchKing. I'm hoping things stay "stable" under Clarus (new owners since last August). I have trusted Sierra for a long time.