If you have taken an antelope at 327 yards that is darn far.
There is one thing about the older M77's that you need to know. The barrels that Ruger used for those rifles were outsourced and not made by them. Some of them are hit or miss for really good accuracy. I'm not saying that all of those early M77s were junk, far from it as I too own one, it's just SOME only give so-so groups. The new M77 mkll's use in house made barrels of a much higher spec and are, as a whole, more accurate than years ago.
So what to do.
I agree with what has been said above. If you do not shoot much it may be hard to recover the costs involved with starting up the hobby of handloading. Try some different factory loads. If you go to your local gun shop he may have other brands or types to try or order. If you don't have that option some fine sources can be located on the internet or by mail order.
Have a REALLY good gunsmith check out your rifle. Some offer accuracy tune ups with a group size guarantee. Your gun might be helped by a good redone crown on the barrel and that bedding job.
I would also see if there is something about your benchrest technique that could help with accuracy. Proper rifle rests with good sandbags and a firm platform with good trigger control technique might help you. If you are leaning over the back of a pickup or have the rifle resting on a rolled up coat that does not help. You say you were in the military so that might not be a problem. My point is step back and see if you can do better.
I would recommend you find someone that already handloads and go over to his place and have him load you some ammo to try. If, after you have tried this several times with different loads you made, your gun responds to these custom loads and if you think you want to get into handloading go for it. Who am I to tell you not to. I think it might be better if you did it with somebody to see the possible expense or boredom involved.
Handloading can get expensive at start-up and for any and all load development process. Once you get into the hobby it might be something you like. Pride in assembly, accuracy, money saved (although this may take AWHILE to recover from the initial purchase of equipment), having fun, stress relief, are all reasons guys have used for getting into handloading. If one of them is your reason then that is a valid reason to start the hobby.
The expense of a true handloading set-up and load development might very well be as much as a new barrel job or a new rifle. For only one rifle it would not pay off. If you are going to expand your gun cabinet inventory then in the long run it might. The old rifle in trade and some extra cash would get you a new M77, or other rifle, that may shoot much better.
Check out all of these options but you are the one to decide.
