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The US Army has been manufacturing 30-06 and 7.62 ammo with bimetal steel/copper jacketing for over 40 years.
It has been proven in military ordnance tests that this does not damage barrels and only increases the wear rate by about 10-15 % in stainless barrels and not at all in chrome lined barrels.
Frankford Arsenal ran a test many moons ago on barrel wear with copper versus bi-metal jacketing and they found there was no difference whatsoever.
This testing was done with US military mfgr. bi-metal jacket ammo with a .008 copper wash thickness over the steel jacket.
Barrels (stainless) are tool steel grade and have a 675 Brinnel hardness rating. Copper jacket has a 35 Brinnel hardness and mild steel jacketing has a 130 Brinnel hardness factor. The bi-metal jacketing would need to have a hardness rating up near 400-500 to cause any actual barrel damage.
IMHO, this is nothing to worry about especially if you have a chrome lined barrel.
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