Batches variations.

[JeffinNZ]

Team.

My No4 MkII .303 Brit has been off the boil lately and I have been wondering why. Last evening I made up a new dummy round based on the seating depth of my current seating die setting dummy and noticed that when it entered the chamber the round seated fully. Usually my rounds stop 50 thou or so short and the bolt seats the boolit into the leade. I measured the new batch of CBE 313 215's I had cast recently and discovered the front driving band was a shade smaller than usual at .3125 instead of .3135 inch. I wound up the seating stem a bit and loaded some new loads to a marginally longer OAL and here is the result at 100m/110 yards today. Seemed to work OK.

http://img.photobucket.com/albums/v505/JeffinNZ/Shooting%20stuff/SC3522157011082216090.jpg

[grouch]

Very nice group, Jeff!!
Grouch

[MtGun44]

Great group! So It sounds like this a change in the alloy getting a bit smaller boolit rather
than throat wear. Anything else going on in the casting process to make this happen that
you know of?n I know I'm not that careful on my alloy batch consistency myself.

Bill

[JeffinNZ]

Great group! So It sounds like this a change in the alloy getting a bit smaller boolit rather
than throat wear. Anything else going on in the casting process to make this happen that
you know of?n I know I'm not that careful on my alloy batch consistency myself.

Bill

Definitely the alloy and not the throat. I tried my other dummy rounds and they all fitted just as they should. Either way, the results are sufficient......:D