Barrel extension shim vs loctite

[kiwi 1]

For what it's worth my opinion is see how it shoots if it is ok then leave it as it is. I would recomend the shim (mechanical) to take up the slack over Locktite (chemical). If you are not happy with the way it shoots then bite the bullet and replace the receiver with one that is a tight fit, this will also help with your confidence in your rifle.