Starman, I have had Aframes compress down into a pancake. Less than half the length of those pictured.
I you could detail the circumstances in which that happened it would be helpful for discussion.
i.e.: impact velocity, cal., weight,target media, along with maybe a photo of the pancake...
BTW have you before seen this image of .416 bullets through water buckets?..
L > R: 400 Barnes X, 400 NF, 400 TBBC, 400 Woodleigh.
But more important than water buckets,the late George Hoffman had an extensive collection of .416 AFs recovered from cape buffalo.
His measurements typical indicated an average .80 - .85 in expanded dia. and 90% weight retention.