There is a lot of history when discussing how the chest rig evolved into what it is today. The one that has probably the most prolific of modern day rigs would have to be the infamous ChiCom Chest Rig which gained its notoriety during the Vietnam War, the Rhodesian Bush Wars, and into the Soviet/Afghanistan War.
Great little history lesson here... https://equipment.fandom.com/wiki/Chicom_Chest_Rig
Even to this day, American SF guys are still wearing these rigs overseas. They are incredibly durable, easily modified, and versatileÂ
With all of this said, I have been a fan of the ChiCom Chest Rig for a long time. It can be worn alone or in conjunction with Load Bearing Equipment and plate carriers and it works for both AR and AK magazines.
I have taken one of my tan rigs (surplus from the Soviet/Afghan War) and heavily modified it to work better for my own needs...
I have put a lot of miles under my rigs and can understand why it has been a staple piece of kit for army's, insurgents, Partisans, and Guerrilla forces for several decades now. No wonder so many new chest rigs hitting the market right now look so much like the ChiCom chest rigs, the design just works.
Looking for a ChiCom Chest Rig?
Ebay listings: https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2332490.m570.l1313&_nkw=chicom+chest+rigs&_sacat=0
Modern Chest Rigs inspired by ChiCom Rigs: https://store.atarmor.com/AT_Armor_Light_Scout_Rig_p/at-lsr.htm
If it works, it works ! Carry a buttload of ammo