I find that when I load up some 338LM I do not generally load 50 or 100 rounds at a time. With this round, I like to experiment with different powders, bullets, seating depths a lot. Add to that, the big, plastic ammo boxes are a pain because they seem huge and I like to use a backpack to put my ammo / range stuff in. The ammo boxes simply don't fit well so I have to carry them around separately. However, these ammo wallets are GREAT because I can separate ammo easily for load development, they're more space efficient and easier to store ammo in, I like the clear pocket so that I can see my load notes, and they fit nicely in a backpack or shooting bag with other gear. Bonus- 338LM ammo fits absolutely perfect in them. I load my ammo to magazine length with 300gr SMK's. Even if the elastic starts to stretch a little over time, they'll still be secure in the wallet because there is no room for them to slide around. I haven't tried this, but longer loads with VLD bullets might be a little tight to get all 20 rounds in??? I'm sure it can be done, but might bulge out the sides or stretch out the flaps. I've been using TAB's other ammo wallets for 308 and waiting impatiently :-) for them to come out with this product for 338LM loads. Funny how something so simple can make a big impact on convenience! Thank You TAB and MHS !!!!!!!!!!