Hi & thanks. I have worked at a gun shop for 42 years, really my only job as a adult. I started gathering up the guns I had scattered around diffirent places to let me enjoy them more. My current quest is to get slings for my old militarys. I have probably had this rifle 20 or 25 years. I know it is a VZ24 with a reworked stock, I have seen a lot of those over the years, what are they? I bought it because I could afford it, unlike 98K's & it had a wonderful bore. And, as I was looking this over I noticed a proof mark in the stock, maybe it's my imagination...but what is that proof? Thanks, & please explain the wrist sling swivel deletion. Thanks.