Everyone has or at least has seen the old style bandoleers the Military sends off ammo in. Usually cotton cloth or something like that. Older ones had seven pockets and held two stripper clips of 10 rounds in each with a card board box keeping it secured in the pocket. The newer ones are 4 pocket and hold three ten round strippers for 30 rounds each.
A dividing string can be removed to allow you to use the pockets to hold 1 thirty round mag in each pocket. Just like the Vietnam era type would hold seven 20 round M16 magazines.
While looking at the new issue bandoleer recently, I noticed it would hold SR-25 pattern magazines in each pocket with the white thread removed.
This gives you a great way to have 80 rounds of 308 ready to go. You can stick it in a pack or put a few in a 50 cal. ammo can and store it ready to grab and go or just have it ready to snatch up and throw over your shoulder and run out to do whatever it is you intend to do with a 308 rifle that takes SR25 pattern mags.
There is still no where the amount of gear made for the 308 mags with the massive selection of gear made for 556 mags. If you have a rifle that takes this type or size mags, this is a very cheap and passingly durable piece of old school gear that can be put into service. Bandoleers filled with ammo and mags served as extra ammo carriers for our infantry through several wars and its still not a bad idea. It is not the best for combat reloads or emergency reloading, but its still a pretty good way to have spare mags bandoleer and ammo on your person or in a assault 3 day pack.