I did a few searches and didn't find many results. I've got a laser cartridge in 9mm that has been great for my semi-autos, but I'm trying to improve with my J frames. There are a few options for these in 38 special, and the price to purchase 5 to fill a cylinder is about that of a few boxes of ammo. I can understand the cartridges being in the cylinder versus the barrel may lead to some inaccuracy and variation, but if anyone has had modest results I may spring for them.