Well I found out for myself. Steyr says they are interchangable. I didnt get the SSG trigger on ebay, but got an M/S triiger off Egunparts for nearly a third of what Steyr wanted. I had to send the rifle in for service as it had a weird malady. If you pushed the bolt handle down at all while fully retracted, it would flip down out of battery and it only took a few pounds of pressure to do this. This is the older model M without the takedown plunger on the root of the bolt handle. 'Smith at Steyr says he (may) be able to make it totally reliable! He didnt sound to encouraging. Second rifle in a row bought off GB that had to get sent back to the factory right off. I sure wish sellers would be more forthcoming with info on their listings. Without knowing that such a thing was possible there is no way a potential buyer would know to ask about it. The other rifle I sent back, built in 1980 would not feed properly of all things! Think someone before me would have had that fixed before now. Factory fixed it and sent it back, no charge. Steyr is already talking about how much this repair is going to cost me. OY!