Harry O
10-11-2010, 03:26 PM
I have a couple of Mannlicher-Schoenauer carbines in 9.5x57 MS caliber. The cost for jacketed bullets is 50 cents to $1 per bullet. I tried several .375"-.378" cast bullets and the only one that I found that would feed was a Lyman 375167. Unfortunately, it is a plain-base bullet.
I tried some of the 375167 that were cast at Bhn 18. They lost accuracy between 1,500 to 1,600fps. Visible leading did not happen until 200 to 300fps more, but by then, accuracy was downright bad. Not good enough to continue. In the distant past, I cast some 30cal bullets from straight monotype. Unfortunately, they broke while crimping them. It was a brittle break straight across where the crimp was. In fact, they would occasionally break apart when dropped off the workbench onto a concrete floor.
Since then, I have been experimenting with 30cal. It appears that everything I tried was pointing toward having as much tin in the mix as there was antimony to keep it from shattering. I have done that with lower Bhn mixes and it worked well enough. So I decided to go all out and try straight monotype, dropped in water, with just enough tin added to match the amount of antimony.
I cast up about 150 bullets today. About two hours after quenching, I tested one at about Bhn 30-32. I sized and lubed them immediately after casting so most of the hardening has not taken place yet. I will be testing them again tomorrow and a few times more for the next few weeks. It will be interesting to see (and graph) the hardening curve. They passed the drop off the bench test. Then I put one in a vice to crush it. It expanded rather than shattered and crumbled apart like the straight monotype ones did. Although my "rule of thumb" is crude (using as much tin as antimony), it appears it works well enough, even with straight monotype.
I will be loading them and trying them out at the range after they have hardened up. I have used XMP5744 for cast loads with this gun in the past. It works well in reduced loads, but it does not completely burn, even at higher than BP pressures. I am thinking of trying IMR4831 this time. A fairly full case of that stuff should give somewhat reduced loads, but fill the case. I am thinking it will be a safe reduced load. I will consider any other suggestions.
I will update this after firing.
I tried some of the 375167 that were cast at Bhn 18. They lost accuracy between 1,500 to 1,600fps. Visible leading did not happen until 200 to 300fps more, but by then, accuracy was downright bad. Not good enough to continue. In the distant past, I cast some 30cal bullets from straight monotype. Unfortunately, they broke while crimping them. It was a brittle break straight across where the crimp was. In fact, they would occasionally break apart when dropped off the workbench onto a concrete floor.
Since then, I have been experimenting with 30cal. It appears that everything I tried was pointing toward having as much tin in the mix as there was antimony to keep it from shattering. I have done that with lower Bhn mixes and it worked well enough. So I decided to go all out and try straight monotype, dropped in water, with just enough tin added to match the amount of antimony.
I cast up about 150 bullets today. About two hours after quenching, I tested one at about Bhn 30-32. I sized and lubed them immediately after casting so most of the hardening has not taken place yet. I will be testing them again tomorrow and a few times more for the next few weeks. It will be interesting to see (and graph) the hardening curve. They passed the drop off the bench test. Then I put one in a vice to crush it. It expanded rather than shattered and crumbled apart like the straight monotype ones did. Although my "rule of thumb" is crude (using as much tin as antimony), it appears it works well enough, even with straight monotype.
I will be loading them and trying them out at the range after they have hardened up. I have used XMP5744 for cast loads with this gun in the past. It works well in reduced loads, but it does not completely burn, even at higher than BP pressures. I am thinking of trying IMR4831 this time. A fairly full case of that stuff should give somewhat reduced loads, but fill the case. I am thinking it will be a safe reduced load. I will consider any other suggestions.
I will update this after firing.