I've got one of the M-77RL Ultra Lights in .250 Savage. I've owned it for around 8 years, and have killed several deer with it. So far, mine loves the 100gr Nosler Ballistic Tips, the 100gr Hornady Spire Points, and the 120 gr Speer Grand Slams. It will shoot all of these into well under an inch for 3 shot groups. It likes H4350 and RL15 for the 100gr bullets and H4831 (regular or SC) for the 120 grainers.
I've tried the Hornady 117gr BTSP's in it and got about 2" groups, but I was in a hurry and it was pouring rain, so I've got further testing to do with that one. It slings the 115gr Nosler Partitions all over the paper in about a 5 inch group. I've got some 120gr Hornady SST's and 115gr Ballistic Tips yet to try in it. It likes the old 120gr Nosler Solid Base's but they don't expand very much and the deer run 100 to 200 yds usually.
I don't know how many of the .250's that Ruger built, but they are rare. You can go to Ruger's website and look up your serial number and see what year yours was built. If you ever decide to sell yours, I'll buy it from you. When you carry it, it doesn't feel at all like a big game rifle. It's like totin a little .22 rifle.