I too have an M77 22-250 from around that same time period. It has in its serial number a 74 or75(I think) and I think thats the year of production. I traded electrical work for it in the late 1990s. A man and his wife owned a small resturant in a strip mall that need its electrical pannel changed out. I'm an electrican and did it for the rifle. It had a 3-9x Weaver on it, I gave that to a friend that won a 270 at a DU dinner, and put a Leupold VX3 6-20. I did a little load development at the time, but not seriously. I also shot California Ground Squirels with it back then. About 2 years ago I got serious. I glass bedded it my self useing a Bedrock kit, free floated the barrel, and sent it to Timoney for their trigger at 2.5 lbs. I have not acurized the action, lapped the lugs, squared the bolt face, ect. I do keep the rifeling really clean though. Then I restarted load development. Got a load that would go 1/4" to 3/8". Then I met a guy who lives close to me who is an expierienced coyote hunter. He took me one day and thats when I found out that my OCL (overal cartrige lenth) (at 10 thousanths off the lands) was too long and the rounds would not fit the magazine!! So it was back to load development. I measured the inside length of the magazine reduced that about 1/8" and rounded it to a rond number. Now it again shoots really tight. I went squirel shooting. Set up on a real nice spot next to my truck. Plastice folding table, Caldwell Rock JR front bench, 2 sand bags rear, lazer range finder, binoculars, and a cold drink. Very first squirel at 285 yards and nailed him. Killed like 35 that day.I have a ggod picture of the M77 I want to post, but I havent figured out how to. Alec