For those interested in the load data
Zastava M70 9.3x62
Bullet: Shock Hammer 258 gr
Powder: 2000MR, starting at 58 gr, moving up in half grain increments to 62.5
COAL: 3.30". I measured the old fashioned way (with a wooden dowel) and with my Hornady COAL measuring tool, and the both showed me at 3.38" OAL where the ogive was in contact with the lands. I have plenty of wiggle room to go up on COAL.
Primers: CCI LR
Chrony: MagnetoSpeed
MVs from 2382 up to 2503, every half grain of powder moved the MV up by 20 - 25 fps
Absolutely zero signs of pressure, even at 62.5 gr. No sticky extractions, no flattened primers, nothing but getting to some impressive recoil
There ended up being about 200 fps difference in MV between measured and predicted. I'm not terribly surprised given the lower pressure and light engraving Hammer bullets are known for.
I may do another 10 shot ladder and move the COAL out to 3.34" so I can increase the powder. At 3.30" and 62.5 gr of 2000MR, I was on the cusp of having a compressed load. Another half grain I think would have been a compressed load. I'd really rather a 258 gr bullet be a bit closer to 2600 fps than 2500 fps.
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Bullet: SAF 286 gr
Powder: 2000MR
Primers: CCI LR
COAL: 3.32"
Again, a 10 shot ladder starting at 58.0 and moving to 62.5 in half grain increments. No signs of overpressure, brass extracted easily at all load levels, no flattened primers, etc.
MV at 58 gr was 2317, and an average increase in MV of 15 - 25 fps for each half grain, up to 2475 fps at 62.5. The delta between predicted by GRT and measured with my MagnetoSpeed was around 80 fps.
The OAL I measured the old-fashioned way and with the Hornady tool were both in agreement again, 3.45". No, that wasn't a type-o, it was 3.45". Obviously there's plenty of wiggle room here to play with COAL as well, but honestly, a 286 gr SAF in the upper 2400s is plenty fast enough, plenty enough recoil, for my tastes.