OzFclass

Interesting find when i was checking my old batch against my newer batch of 155.5 fullbores

That's a 32 thou variation -- I can show them to you with a 53 thou variation.

Ill definitely be checking all future batched after finding this and also from what you have said Barry, Im not sure if its a change in design or just a manufacturing tolerance? I checked 60 of the new batch and they were all withing .001 +/- .001 The newer ones were the shorter measuring of the two.

This is not a variation between "old " and " new " batches. The variation I stated was between two batches only months apart.
I also have two other batches which are different again. Usually within a box ( same batch ) you can get up to 6 thou variation. I measure every damn one --seems like the manufacturing dies are different.
In this day and age of hi-tech CNC machines repeatability seems to still be a problem.
They shoot differently too.
When you purchase projectiles make sure you get enough for the life of the barrel AND all of the same batch -- it's the only chance for consistency.

My new batch are 80 thou longer .

Cheers Trev.

I thought it could be at least partially due to either a change in the dies after a set has worn or running multiple machines with slight differences in dies producing two different batches? Thus creating two batches close in time but maybe not so much in dimension. The guys who make custom bullets would know?

This apparently is uncommon, an Mr. mcried is correct with his comments on dies, as long as you are not seeing variations like this within the same batch you wont have any issues, Bryan Litz did a short article about this some years ago

Berger/Spiveco/J4 have had control of the tool room for tool long now and know the consequences of any significant variation in their tooling. I believe they acquired their tooling supplier to ensure supply and quality control. They also learnt not to try and swap products between presses/production lines.

Most likely a small variation in the thickness of the gilding metal strip coil supply. There are limits as to what the mills can roll in terms of thickness, regardless of how much money you put on the table. If the thickness is within limits and the grain size is good you can at least deep draw a decent jacket. Supply of quality gilding metal is too short to reject on thickness alone.

Always worth checking your handloads are maintaining the same point of impact if you swap out any of the components with a new batch; and for those running on the ragged edge of pressure or a narrow node it would definitely be your interest.

With the cost of these projectiles large differences in measurements should not happen. Recently had a load sorted out and went on to a new lot and they were .080 longer base to ogive. Great when the load I was using was .020 off the lands. Start load development again and wast more time, barrel and bullets. Anyone running warm loads that might not have checked could have ended up with serious pressure problems jamming them .060 without knowing. Only a short time ago I had a batch of Berger's that had patches of green corrosion all over them and honestly at least 50% had to be rejected as not suitable for loading. Not good enough! We are paying for a premium match grade projectile and getting a shit product. Rumours are around about a new HBC projectile and if the quality is up where it should be then I wont be partaking in the Berger lucky dip any longer and getting stuck with a shitload of unusable projectiles. Regards Malcolm.