There was a posting here few months ago that indicated he thought
most cracked slides were because of improper lightening of the
slides … If you can find that post, you'll be well ahead in your
search for the perfect powder.
But, as FTP mentioned, 3n38 is probably a good bet for powder.
Another way to look at it, is that 100,000 rounds will cost you c. $12,000+
for the ammunition. By the time you've spent $12,000+ for ammo, you
might not mind too much spending $1,000 to update your blaster.