I use Allen medium elastic type $4.95 Heat up 16 penny nail melt through bottom put over sling swivel stud and stays put. I have put 300 mag, 270 win, 22-250 in same holder. If you don't store cartidges for extened period the elastic will hold all three. I only put 300 mag for 10 day elk hunt it is a little tight! Then back to 270 for Utah Mule deer and Missouri Whitetail 3 weeks then all winter with 22-250 Rabbits and Yotes have had same holder for three years still holding all three. When I bought the Allen I got 2 thinking I would need one for 300 mag and one for the 270, 22-250 one is still got cardboard and price tag on it.
Hog