I have my Dads m37 and they are wonderful guns for sure. I have had my best luck ordering my shells from the following sources
Bass Pro. Remington game loads
Cabelas. Herters
Gramaile Shooters Supply. Nobel Sports
Basically I shoot either 7 1/2 or #6 shot and find thos cover most all of my bird hunting as well as small game. I have a couple of 5 round boxes of #1 buck probably 25 years old.
