Help w/ Model 30 Series and barrel type designations

[OreMetz]

I have a 12ga Model 30F Type 3 shotgun that I received for Christmas around 1975 or 1976 and I would like to get a shortened barrel for home defense. I want to be able to swap out the 28" Ribbed barrel that is for hunting or trap with an 18-18.5" barrel for home defense. Are these other series and designations ok for use on my shotgun?

[Mad Dog]

Yes, most of the series designation letters have to do with small internal parts and stock variations.

[OreMetz]

Thanks! just debating with buying a used barrel for $100 or so and cutting it down to a 18.5" (just to be sure there isn't a problem) in lieu of buying a inexpensive shotgun like a Savage/Stevens 350 for a $100 bucks more........