The first article on reloading I read was by Col. Jeff Cooper, about the problem of 38 Special target loads blowing up guns with 2.7 grains of Bullseye powder. That article has kept me safe for more than forty years. Bullseye and other fast burning economical powders are dense, and not much is needed in each load. A double load that gets past your quality control can blow up your gun. Exploded guns show up frequently on the Internet, and it usually comes back to quality control by the person loading the ammo.
Hercules/Alliant pistol powders have been difficult to obtain in the last several years, so most of us can't find Bullseye, Unique, Herco, Blue Dot and 2400. Study current burn rate charts to find powders that will be similar in burn rate to the old standards you have used, and then find published, safe loading information for them. I've been using Winchester 244 and Hodgdon Tite Group of late.
Tite Group is very close in burn and charge rates to Bullseye, so you must be diligent in loading it. Win 244 is closer to Unique in burn and charge rates. It fits in about the same niche as Win 231. Study the photos at the top of the post and note how little space a charge of Tite Group occupies in a 38 Special case. A double charge is nearly the same as the maximum charge of this powder for a 357 load. That is enough to split a cylinder in a 38. You can easily fit four charges in a case and still load a bullet. If you are new to reloading, start with a single stage press and learn the processes before you move on to a progressive loader. Slow and steady makes for safe loads.
