.243AI load.

[menial 1]

Loaded some 85gr Sierra spitzer in Lapua cases with 45gr Viht 160, CCI large rifle primers and set them at 10thou out as a starting load, the primers ended up cratered and the bottom of the cases were well marked. Usual load for .243 with the same bullet was 43.5gr Viht 160, CCI large rifle, set 40thou out as this had proved to be the most accurate with the previous barrel on the .243 and gave 3080fps with no signs of pressure. Present barrel is 22" Pacnor 1in9 .243AI.

Any ideas as to the cause would be appreciated as I assumed that 45gr would be a relatively mild starting load for this bullet in .243AI.

I'll load a few more at a reduced load of 43gr to try again, but feel I'm missing something here.

Pete.

[mildot]

Were they fireformed cases or standard .243 that you were fireforming?????

 

If they were standard cases then thats the prob! I found that when fireforming i used 43gr of imr 4350 but once formed i could ramp up to 45gr.(different powders i kow but principle is the same)

[menial 1]

Were they fireformed cases or standard .243 that you were fireforming?????

 

If they were standard cases then thats the prob! I found that when fireforming i used 43gr of imr 4350 but once formed i could ramp up to 45gr.(different powders i kow but principle is the same)

 

These were fireformed cases, normal load with the same bullet in .243 was 43.5gr, had to reduce fireforming load to 42gr because of similar pressure signs.

Wondered if primer change could help.

It's left me scratching my head a bit, as I expected to move up at least 3-4gr over original .243 load.

Pete.

[Andrew]

When I got my 17 Mach IV rifle built I used a starting load that was well established for the cartridge. I blew the primers out. Meaning, what worked in a previous barrel has no relevance with your new tube. Gotta start from scratch with a new chamber and barrel. JMHO of course.~Andrew

[menial 1]

When I got my 17 Mach IV rifle built I used a starting load that was well established for the cartridge. I blew the primers out. Meaning, what worked in a previous barrel has no relevance with your new tube. Gotta start from scratch with a new chamber and barrel. JMHO of course.~Andrew

 

You're not wrong Andrew, I tried 42gr Viht 160 this afternoon and had no dramas, will work up in .3 increments to a happy load. Not bothered about achieving mental velocities, just looking for a safe baseline to work from.

I had it sussed with .243 but ths Ackley tube doesn't forgive so easily.

Pete.