problem with 338 hybrid base to ogive

[panzer075]

So I have been working up loads with my new 338 Norma. Have been having weird ES problem. In testing I will have 7-8 shots in a test string with an ES of 4-6 fps with several at the same speed. Then 2-3 open the ES up to 18-25. I anneal my brass hand weigh charges.

So I start sorting the bullets...berger 338 OTM hybrids. I had 2 boxes left. Out of 200 bullets from the same lot#6122 I got base to ogive variances of .0125 from longest to shortest. And the average variances were .005. I have 6 boxes of bullets.

I know this isn't normal for Berger..I must have a bad lot...my question is could this wide variance explain my weird ES problem or should I keep tuning?

I do have to feed from a mag and they are jumping .050 but I didn't think it excessive. But this is my first 338 NM so I didn't know if it didn't like jumps..

It is not a typo.....0125 variance in BTO...been triple checked..

 

[Bryan Litz Ballistics]

Sir,

Please email me at: bryan.litz@bergerbullets.com

I'll put you in contact with Berger's production manager.

The variations in BTO that you're reporting are way out of spec, and not typical for that bullet. Our production guy will be interested in the details, and will probably offer to replace your unopened boxes if he's able to confirm your measurements.

BTW, it would be an interesting test if you picked 5 bullets having the same BTO, then 1 very short and 1 very long. Shoot them over your chrono to see if the velocity outliers correspond to the BTO outliers.

FWIW, extreme spreads of 20 fps are not bad. That would put your SD around 5 fps.

-Bryan

 

[panzer075]

Thank Bryan
I don't need replacements I only have 180 bullets left. I have been well taken care of by Berger in the past and I am sure this is an anomaly. I just received a shipment of 3000, 30 cal 200 hybrids and the variation in the couple hundred I checked randomly was only .002-.004.
Maybe I will rebarrel to 300 Norma..lol

I am planning on running tests with these bullets to see what happens. I already loaded up a 20 RD test exactly as you described with 5 designated long or short shots to see what happens.