It is pretty useful, adjusts quick. It's a GI M1 Garand cotton web sling. They make nylon ones now too. Ebay/Amazon has em. If you do the same, might want to remove the metal hook like I did so it doesn't wear on the stock.
Will you guys who want x39 be reloading for it...
I had a remington mini mauser in x39 years ago and the availability of accurate factory ammo was nil.
Sold it before starting to reload.
I have 2 527 in 7.62x39 and my experience with them is this if you plan to reload the chambers are cut to CIP dimensions which can cause problems with reloads. To reduce the likelihood of misfires with both factory ammo and reloads replace the firing pin spring. They are very easy to change out and can be had from JP enterprises for $16.