We have weighed alot with guts in. The biggest we have weighed were in the 265-270 lb range live weight.
Dad kept records and the most he ever had one lose was 38 lbs, with the average mature buck losing 30-35 lbs by field dressing. When you see guys talking 50+ pound losses with dressing...well....
Of course time of year matters, the buck I just killed in Indiana was this size (265), but he would have lost alot by mid November, probably 20-30 lbs I'd guess. He had fat pads 2 inches thick over his hips and rump.
Here in Indiana the 4 1/2 yr old and better bucks I've killed were all 240-265 live wt. In Iowa on Dads old farm the average 4-5 yr old buck was in the 220 range with only a handful of the really big ones over the years. Genetics? Feed? I don't know, but the Ohio/indiana bucks we weighed averaged more than the iowa bucks.
That one you are talking about was in that 250-260 range.
R