Got a trombone and can't find anything online about it. The bell says New Standard Master-Tone Trombone for Daynes Music Co. The bell is friction fit so I was wondering when friction fit were used commonly for a general estimation to date the trombone.

Friction fit was generally used before around 1930, although I have a Conn trombone with a bell nut that is older and have seen newer instruments with friction fit.

For Olds, friction-fit was the norm through the 1930's. Since the serial number vs. date of manufacture is imprecise, there's some question as to whether the transition took place before the US entry in to WWII and the subsequent pause in musical instrument manufacturing. I'm inclined to think it was maybe a year or so before.

I wonder if it's the Daynes Music Company in Utah? They've been around since 1862; they're piano specialists now, but I get the impression that they served a broader market at one time.