I have killed right at 75 pigs in the last 12 months. Most have been in or around peanut fields. The pigs cause us lots of trouble here with crops. I would say we have better than average growing conditions for pigs due to the combination of cover and irrigated crops. We have quite a few larger than average pigs. Anything over 200 is a pretty dang good pig though.
I started out using a tape and doing the heart/girth measurement thing, but to be honest I'm not sure how accurate that is. We shot a pregnant sow last spring rooting peanuts that according to the tape was over 275. Not long after that I bought a scale and carry it plus a hoist with me when I go pig hunting. If it looks interesting, and if I have time I try to weigh them. Otherwise drag them off or leave them lay according to landowner wishes. I have killed 3-4 more sows out of that one field in the last year that were legit weighted on a scale 200 lb class pigs. At a different place last fall I killed a sow and a boar at the same time over a pig barrel. Sow weighted 199 and the boar 224. One night last fall me and a friend killed some pigs out of one of his peanut fields. Didn't have time to weight the big sow, but she was the real deal. I'm guessing 250 from just seeing and weighing a lot of others from that area but I don't know. Killed a couple more big old sows in another field 2-3 miles from that one, 190-220 lbs.
Doing crop damage control work we stalk big sounders in open fields at night, start with the big pregnant sows or sows with litters and work down, so many of the ones we kill are the top end, cream of the crop. The biggest ones are the ones to go down in the initial countdown shot.
I did kill a big old boar down by Ozona a few years ago. I'm not going to say the numbers several other experienced folks threw out because I think they are on the high but it was for sure a legit 300, and probably closer to 325 lb boar.
Not a very good picture but these were 199 and 224, verified on a scale the next day. So maybe a touch heavier when first killed.
Boar in this picture was 195 lb.
Couple pretty decent sows in this batch, maybe 170-180.
Big preggo sow here pushing 200.