About my M77 .22

[loiblb]

About 18 or 20 years ago I bought a stainless gray all weather M77 in .22lr with a laminated stock.
I was told that some needed a shim in the bolt and some of the guns the barrel could be switched out.
What can you tell me about this? The gun is coming out of storage and I will b shooting it.
Thanks

 

[Mobuck]

No clue as to the need for a 'shim', but would assume this to snug up the headspace. My late 80's vintage 77/22 has fired a bajillion rounds w/o any issues so unless you discover a serious issue, disregard the shim suggestion.
Switching" the barrel? For what reason? I have a spare barrel for my 77/17HMR that has been threaded for a muzzle attachment. Changing barrels to one of the same profile is fairly straightforward but not something I'd do frequently.