I am currently using a RIMS set up for mashing in a ten gallon pot on the stovetop. I like it because I can step mash and have been hitting 75% or better efficiency routinely. However, I have noticed as I start to increase my grain bill my flow rate becomes a trickle. I am using a perforated false bottom in my mashtun. I thought at first it was because of the flow rate being too fast. But now I think it's because of the added weight of the grain compressing the grist. My last brew was 15 1/2 lbs of grain - I could not get it to recirculate as it kept plugging the screen. Again this has not happened with smaller grain bills (10 - 12lbs) even with more than 50% wheat. I am thinking about getting a Blichmann false bottom. Does anyone out there use one with a RIMS and if so do you like it?