DON'T PACK IT TOO TIGHT!!!!
I use 777 FFFG in my Bobcat & I had to learn that one lesson the hard way.
When I load the powder I have the barrel at an angle away from me but the lock side down to try to get some of the powder into the flash chamber because it is kinda small back there, I then will give it a slight tap on the side of the barrel to settle the powder, & then load my PRB to where it just touches the powder with practically no compression.
This has been the most reliable way to keep mine going during the range sessions & it does help to keep the groups pretty consistent too.