older laminated glass used a different core material, newer stuff is more 'elastic' [polyvinyl buterate?], also the core material, being plastic, deteriorates w/ exposure to UV, so any 50 year old glass won't have near the laminating quality left that it originally had - the lamination should be obvious in a broken window, and it wasn't meant to prevent the shards, just to keep it from flyin around
laminated glass does go thru a heat process that might anneal it to some extent, but I don't think the full annealing process could be done on laminated as it seems it would affect the core plastic adversely
if the new windshields were tempered as well the break would be very small pieces of fairly uniform size, which I've not seen, so I think it's just that they have much better core plastic now
"bullet proof" glass is just laminated glass w/ multiple laminations and thicker layers, and it can be done well enuff to really stop bullets, and GM didn't waste money!
Bill
