Since WW1 the question of changing barrels and barrel life has been an issue for MGs. The best option yet found has been the chain guns which are a varient of the old gatling guns and the cooling effect of spinning multiple barrels in free air to cool them.
Water cooling as used in the maxim type MGs (vickers etc) worked reasonably well but produced visible steam clouds after sustained firing.
The simple fact is that you cannot put considerable numbers of modern velocity rounds down any metal tube without adverse heating. Modern alloys, eg cobalt in this case, may well reduce the effect but they don’t do anything to remove the source problem of heat build up.
No question water cooling jackets are the most effective way to increase barrel life for ground MGs. But, in addition to producing steam, weapon weight is increased greatly, plus there can be a logistical problem created in obtaining water in the quantities needed. Therefore, weapon mobility on the battlefield is greatly compromised. There were some notable examples during WWI of very prolonged duration automatic fire for area denial purposes involving water-jacketed Vickers guns, but these guns were mounted in stationary positions. And of course WWI was fought mainly from static positions, i.e. trench warfare, largely because the widespread use of heavy machine guns by all combatants prevented mobility.
The issue is the loss of yield strength of barrel steels at high temperatures. I have seen MG barrels that were essentially melted and deformed from continuous firing. If barrels using the cobalt alloy can reduce this problem, they may well be very valuable in extending barrel change intervals, although I doubt that it is possible to ever completely eliminate the need for changing barrels quickly. I notice that the article provided very little in the way of technical details, and actual barrel performance may not live up to expectations.
Multi-barreled guns are also effective in prolonged fire without barrel changes, but again are impractical for ordinary ground use due to their weight (including the enormous weight of all the ammunition required) and the need for a separate electrical power source. They are best employed from vehicles and aircraft. Of course, Jesse Ventura used a man-mounted 5.56mm six-pack for shooting alien predators.
By the way, a cobalt alloy called Stellite was/is used to line chambers of .50 BMGs. Maybe this is the same alloy PA is working with. That stuff is extremely hard and extremely difficult to machine. I’d guess a whole barrel made of it would be just as extremely costly.
850 Rounds in under 2 minutes from an M60 E4:
youtube.com/watch?v=mBNGgu0q … dded#at=50
Think I have read somewhere that the oprod front end on a Garand is made from Stellite. Would make sense I guess.