I used a lot of 1.5 Montgomery ROUND JAW traps in the 80's and later into the 90's. Still have 130 or so of both closed and factory offset jaws. Most have been modded but a few still are as they came from the factory with just an added swivel. My experience with these is it is a poor water trap and poor land trap for coons.It is a good trap for a mixed red fox/coyote area where coons are scarce (where's that now-a-days? LOL). Spring strength is too much and self damage (land sets) was too high for me for coons and in the water, those short lever ends were a bugger to set when you had muddy gloves. I filed all the jaw faces flat for the closed jaw model as they were made from round rods pressed to make the round surface and the ends machined to fit thru into the frame. I did like the holding power and tough frame when a coyote ambled into a fox set, so if you placed it right, you had a coyote fur even with a toe catch. When MB traps came out, I called my Mont. 1.5 round jaws, a poor-man's 450. The Northern Trap may have solved some of those things I didn't care for with the stock Montgomery. Use these 40 year olds when I want a memory and a few of my old 1980's # 2 ROUND JAW Montgomeries also. Interesting post with the Northern design ................... the mike