rasmuz, Good luck getting your 77RL to shoot. I have one, with tang safety, and one thing I've had to do is load light to moderate loads with 100gr or less bullets. I can load 120gr bullets but the velocity has to be around 2500fps at 10ft from muzzle. Another temporary fix is a poor mans bedding using pieces of credit card as spacers to get the action off the wood and preload the barrel about 5lbs an inch or two in from the end of the forearm. These spacers are only an interim solution until I glass bed with pillars. Even after it's glass bedded I don't expect it to group less than 1" at 100 yards nor be able to handle loads near max listings. Oh, another thing is I changed the trigger to a Timney and tuned it to a crisp 3# pull. If you decide to install a Timney trigger you'll have to remove some stock for clearance. Also, with the MK II's, I've read that something needs to be adjusted with the safety, so it might be in your best interest to have a smith do it for you. Lastly, with that thin barrel give plenty of time between shots, the barrel heats up very quickly.
Bill