I have a new-to-me hk marked m1, it's got the very old style Surefire on it (before they were called surefire even!) and I'm not crazy about it, seems heavy for what it is.   I'm considering a factory fore end for it, but I'm having trouble figuring out if it'll fit or not. My serial is m090something iirc. Surefire has a note on their site saying their new weapon lights for that model only fit m1's that are M104800 and above.   I found a guy selling a couple fore ends for a (imo) too high