Easo,
Steel core or steel penetrator ammo for 5.56 has been around for many years: the SS109 (M855) has a steel penetrator (so I suppose it has a lighter 'nose' with the CofG toward the rear where the lead slug is?). It was a longer (23mm compared to 19.3mm) and heavier (62 grains compared to 56 grains) than the earlier Vietnam-era M193 Ball ammunition, with less tendency to breakup or deviate on impact. The MV was also smaller (3025fps compared to 3250fps, new rifle at 75 feet from the muzzle).[figures from TM43-0001-27: Army Ammunition Data Sheets Small Caliber Ammunition FSC1305] Initially, the M193 was retained (while stock lasted?) and the M855 was issued in belts only for the M249E1 SAW.
What the US adopted was a 5.56 projectile that uses a steel penetrator and less lead, substituting an alloy of some sort. This is the recently introduced M855A1. I don't have specs at hand to compare it to the M855.
So I suppose its OK to use Uranium depleted rounds on AFVs etc, but more environmentally friendly to use lower/none lead Ball ammo. Hmmm.... kinda makes as much sense to me as the Poms 'sanitizing' the wood plug in their .303 rounds to avoid infection of the gaping wound it caused.
Mike C
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