I've shot an awful lot of 4320 through a 17 and never found it to bad for fouling. When I first had mine I fell into the 17's foul badly and need to be cleaned every 20 shots mindset. One trip to the ground squirrel killing fields cured me of that. The first day I was cleaning pretty frequently and about to swear off the 17 because of all the barrel cleaning. The next day I shot without cleaning till I ran out of squirrels and daylight. Just for grins and giggles I shot a group with it after somewhere north of 250 rounds of squirrel shooting. It was still grouping a little under 3/4", which was normal for that rifle. It would run around 1/2 to 3/4 inch groups most any day. Half inch if I was on, 3/4" if I wasn't. I quit the OCD cleaning regimen after that. Once or twice a year now whether it needs it or not.
I wouldn't stress too much about fouling.
