Well thank you for your time and and advice, it helps somewhat.
I have seen some pics/vids of Arnold when he was really young like age 20 where the bottom was big enough it was 'overlapping' while relaxed but looked a little thicker then compared to some pics/vids in his 'peak'...whatever year that was (where it looked slightly longer/lower while relaxed and overall would be bigger)... So that's what prompted this, odd rare Inquisition.
I like 'Pumping Iron' a lot... is it possible that his chest was not any bigger then lets say age 20, which is the year/vid I 'see/wondering about as being thicker' b/c he lost muscle mass due to films that year?... Naw I still think his chest, at least overall, was way bigger even at 225lbs in 1975 then compared to age 20, even though he was pretty bulky... I suppose it could be water/fat, angle, etc. too... but I wish I could KNOW for sure.