OzFclass

G'day All,

Deceided to check the bearing length variation in a bulk pack
of .308" Sierra 155 SMK's (original style). Used a Sinclair comparator
and digi calipers and ended up with basically 2 piles in which the projectiles
were within 3 thou. of each other. Out of 200 odd had a handful that were out of spec but also measured a few more that were WAY out, I mean around 35 thou short. Question from me...is it normal practice to batch your
bullets?

Chris

Can't hurt if it you have the time. I batch by weight, bearing surface, base to ogive then trim meplats...might get into pointing one day too. I'm confident my ammunition is as consistent as I can get it...doesn't mean I can do it justice or that all that time has amounted to anything of value. For what it's worth a 500 box of Sierra 6.5mm 142gr MK's basically batched into two lots as well but their wasn't a HUGE variation between the two.

Michael

Chris S wrote: Question from me...is it normal practice to batch your bullets?

That's what they designed the Bathurst 1000 & test match cricket for - to make a boring bloody job somewhat less so.

You're correct that you can weed out the grossly irregular profiles, but Eric Stecker of Berger Bullets once stated that with the quality of equipment we use to do the measurements, it's not possible to measure to better than a few thou. In a fit of missionary zeal, I rechecked 1000 200 SMKs I had batched & found that he was more or less correct.

These days I'm about comfortable that bearing surface has a strong correlation to OAL & I perform a batching of sorts when I meplat my projectiles after touching up the nose with my Whidden pointing die.

Michael, meplatting becomes a much more logical process when done after pointing, as I see it.

John

Chris,

My advice is to check a sample (say 20) of each new batch of Sierras you buy for base to ogive, and depending on what you find sort them (or not). I once got a 500 box which turned out to be seconds, and they varied by 20 thou.

Alan

AlanF wrote:I once got a 500 box which turned out to be seconds, and they varied by 20 thou.

Jenni Hausler has a box of 210 SMKs where they vary by thirty thou - on diameter. She's the proud owner of one 250 grain & one 300 grain .338 projectile.

I agree whole heartedly about trimming meplats after pointing but I don't have a pointing die as yet so just spend my time grinding off the meplats and turning my once super slippery high BC projectiles into glorified hunting hollow points!!

Michael