While that is likely true of the Bushmaster AR's tested with 5.56 in that article, the M14 platform is a different matter.
Bushmaster uses commercial barrels with arguably less robust chrome lining than milspec barrels. Also, they used Brown Bear, Wolf and Tula ammo as their examples of bimetal ammo, and used top quality Lake City/Federal ammo as the basis for comparison. All these cheaper brands are made in Russia at state-run arms factories that usually make 5.45mm and 7.62mm AK ammo for Russia's limitless supply of cheap AKM series rifles.
I would submit that milspec M80 ball with thick guilding in a boxer primed brass case with IMR4895 powder is not really comparable steel cased Russian ammo with a copper washed steel jacket.
5.56 is also significantly hotter/faster than 7.62x51 with a much smaller bore diameter - factors known to accelerate barrel wear.
You also have to look at the relative cost of ammo compared to the cost of a new barrel. An M14 barrel, even a krieger, is around $600 installed. If the bimetal ammo is cheaper by more than $600 over the life of the barrel, you likely still come out ahead.
It's also important to note they ran those guns hard, fast and hot. "Excessive upper receiver heat did cause thermal discoloration of and cosmetic damage to the EOTech sights.". think about that, they burned those barrels out with so much rapid fire that they heat affected the eotech sights on the uppers. they say the guns stayed under 750F. I'm skeptical - that would not change the anodizing colour on an eotech housing. And 750F is still 400C - think about that. Your kitchen oven can't get that hot, and they maintained those temps long enough to fire 10,000 rounds (!).
Bimetal rounds have increased barrel friction and WILL heat up a barrel faster on full auto. On high volume machineguns, that is why stellite liners were developed - for bimetal rounds with very high rates of fire. It's unlikely you will have this kind of issue in canada with semi-auto rifles and 5 round mag limits (!).
From the article:
Why Did The Barrels Wear The Way They Did? “Because we shot them until they got hot, and then we kept shooting them.”
When they dissected the barrels, the throats were evenly worn in all 4 barrels, and all 4 had gas ports worn to the point of not being in spec. The federal ammo had the worst gas port.
So all that to say, for the average shooter not running full auto or very fast semi-auto until you get he barrel over 400C, you'll never see the return on investment for the difference in ammo price. If you actually shoot 6000+ rounds of bimetal M80, to be frank, you'd likely want to change you barrel anyhow as even the best ammo will see a barrel's optimal accuracy decrease by that point.
