88cm

There's a line-of-sight thickness on the M1A1 that's 880mm thick.

GURPS is DR 70 per inch of RHAE.

880mm is 34.64".  If it were rolled homogeneous armor, it'd have DR 2,425.

I'd given the M1A1(HA) DR 2,400L in this facing.

It's my understanding that even Chobham armor is better than its RHA thickness.

It's kind of why we have the phrase RHAE where the 'E' means "equivalent."

Challenger 2's version is supposedly good for double it's thickness for RHAE.  If the M1A1 is using the same blend, then the 88cm section should be DR 4,850L!!!

What they're NOT clear about in these speculations is if this is the effective thickness against a particular round or if that's against anything.

If we're talking about JUST HEAT rounds then this is exactly what the rules say laminate armor should do to a HEAT round.

For the record.  DR 2,425L needs a 6dx23(10) cr ex HEAT round to start worrying.

The "Dorchester" version in the Challenger 2 doesn't have the depleted uranium the M1A1(HA) has.

Even so, this stuff appears to be better than normal steel of a similar thickness against KE rounds.

Ye Olde GURPS: Vehicles makes laminate armor lighter for the same protection, so I'm going to make it the same DR as its thickness in RHA.

The DU plates seem to me that it might make it hardened armor and that'd change the armor divisor of the KE round from (2) to none at all.  That means it takes 6dx115 pi++ to punch!

I have no idea if this is even realistic.  The DU armor hasn't been tested in combat by a serious opponent.  The Iraqis didn't have the top shelf ammo for their tanks and the standard DR 2,425 is sufficient to stop 6xd58(2) pi++.  The 3BM46 "Svinets" round is only good for 6dx37(2) pi++, 3BM42M "Lekalo" is 6dx48(2) pi++.

Note: these are all "average" hits were every die rolls 3.5 points.  The lightest hit that can penetrate DR 2,425L is 6dx33.7(2) pi++ with a max damage roll.  6dx202.1(2) pi++ punches on a minimum roll...