I used some Fed.209A's when I got my prohunter. They caused allot of blow back,and it is primer residue,not burnt 777 powder. I can't tell any diffrence in accuracy,no matter what primer I use. I CAN tell a diffrence in the crud ring though. If you are getting true blow back,the threaded area on the breech plug will be pretty fouled up. Some times it is caused by not having the compression ringsd lined up. Here's another post I made concerning this. Hope it helps. Ron
Dave,what powder are you using? Is it getting crud in the threads? One thing you might check is,on the front of the breech plug,there are 3 little rings(compression rings). They have a little open area at the end of each one. You need to clean this area very well,and use some penetrating oil (breakfree,kroil) to clean them,and float the fouling out. After cleaning them,make sure that the openings at the ends don't line up,in other words rotate them so they are at three diffrent locations on the breech plug end. Using a clock face as a refrence, place one at 12, one at 4, and the last one at 8,O'Clock. This is the same system that is used on the AR15 rifle bolts,and unless they are seperated,you will get blow by. Hope this helps. Ron