The Progressive Musical Instrument Corp. was a big US distributor starting in the early 1920's, (maybe even 1920), in NYC. The name P'IMCO was registered in 1923 and as with Bruno and the like, they never actually made their own instrument they just distributed others, (This could be said of a lot of the big Ukulele names of today too). They were probably better known for their woodwind instruments but they did always carry a range of Ukuleles and Banjoleles, made but the firms like Harmony and Regal and I have read that they also used Rutan Inc. for some of the Peter Pans?) As well as just being branded P'IMCO they also had brand names such as Armstrong, Peter Pan and My Buddy (all reg. 1924), Ha Ha the Laffing Uke, (1926), Buckaroo and Nobility, (1931), and they also used Collegiate. Some of these I have only seen the tm registration for, not an actual product however here is part of an article from the 17/4/1926 Musical Trade Review for the introduction of Ha Ha the Laffing Uke

"Laughing Ukulele Is Offered for Summer Trade Progressive Musical Instrument Corp. Introduced Novel New Instrument to the Market—To Be Strongly Featured in Campaign The Progressive Musical Instrument Corp. is out with a new item that is bound to stimulate Spring and Summer sales in the Ha-Ha,"The Laughing Ukulele." This ukulele actually appears to laugh and opens its mouth in a big broad smile. In addition to this its tone quality is of an exceptionally high standard. In an interview with The Review, Benjamin Landay, in charge of musical sales, said: "The Ha-Ha Laughing Uke is going to be one of the biggest things in music this year, and, before the summer is over, there will be thousands upon thousands in use for there is no greater article for vacation time than the ukulele. We have especially prepared window streamers advertising the Ha-Ha Laughing Uke, which are distributed free with each order of a dozen of these ukuleles. It is going to be a big $5.00 retail seller, and is well worth its price.

Like most distributors of the time, as well as seen the brand names they registered, there are names that they used but I have not found the registration for so they may just be the distributor but not the actual brand owner. One name they distributed is Perfecktone, this was used on a lot of instruments, most famously brass and woodwind, but in the mid 20's there were Guitars, Mandolins and Banjos, including Banjoleles, with this branding, (I've not seen any Ukuleles though). Another brand they distributed was Indian Head. This was the brand name for their stings and Banjo vellums and I have never seen any documentation to say it was ever used on instruments? However a publicity pieces for this brand is the best explanation I can come up with for the instruments with no marking other than the Indian Head on the headstock that I have pictured?

I have also seen that in 1926 they claimed to be the sole distributors for Al Jolson, Eddie Cantor and Cliff Edwards, Ukulele based merchandise, (Cliff Edwards may have used other distributors later on). They certainly were for May Singhi Breen, an early writer of play the Ukulele books, as they registered her name for use on Ukuleles in 1925

I believe they ceased trading in 1960.

I know of a few people who have misread the name with the stylized P and lack of a first vowel and decided they had an Amigo branded instrument