Pick up one of the Rossi single shot pistol . I wount use the 410 to much but I want tto try out the 450 mongo . Picked up 50 pcs of 444 brass at local big box store. Took and used the 44 mag expander then 45 to open up the case mouth.H ad some large rifle primers from whe I reloaded 30-06 so I thought i would then up. Reloaded 30 rounds with 12 grains of Trail Boss and a 200 grain lazer cast bullet to fire forn the shell. 20 out of the 30 fail to fire. Came back to the house and load up 10 rounds with just the large rifle primer. 2 out of 10 FTF. Loaded up 10 rounds with large pistol primers,all fired. the LR primers are 6-7 years old so could be the problem. Primers did have a ,look to me, like a lite firepin hit. Remington primers. Going to load up some with larege pistol primers and give the a try,same load