Rod,
Do you recall the write up that went on for several pages regarding the 25-20? It was on marlinowners.com Very thorough. Posted by 35remington.
In the section he compares powders, he says the 4198's and RL-7 are "pretty close". He didn't specifically mention the 60 gr Hornady with RL 7 though. He talks about using your bullet with 15 grs of H-4198 gets to 2300fps and 14 grs of the same reaches 2250 fps.
He does say that the case size makes it difficult to load too much RL 7 in and get into trouble.
Hope this helps some. I've used IMR 4227 with the 60 gr Horn. It's OK.
