I aquired one back in the early 90's when they were still "cheap". The thing had the 24 inch heavy barrel and shot well, but weighed in at 11 pounds. I wanted to obtain a 16 inch lighter carbine upper, but Knight's quoted me a ridiculous price (for the time) for one. I proceeded to build an upper based on Armalite AR 10 parts, then available from Armalite. I had to modify a number of items to get the hybrid rifle to function. (it still functions well with the original SR 25 upper.) I installed a 16 inch fluted Blackstar cryo-treated barrel. The thing still shoots at 0.5 inch and sometimes under when I do my part.