It's a bear!

LM-7 "Military" Model
Bore: .485"-.500" (12.3 mm-12.7 mm)
Bell: 7" (177.8 mm)

At first glance, the Military appears to be simply a Self Balancing with the addition of a "dazzling hammered finish" (to quote the Olds description), but closer examination reveals a second, possibly more significant, difference - one-piece outer slide tubes, with an area of increased wall thickness in place of the soldered-on oversleeves used on other Olds trombones of the time. Olds had pioneered one-piece inner slide tubes (elimiating the need for soldered-on stockings) several years earlier, and the Military was their first model to incorporate outer tubes made using the same technique (the slight step in the outside diameter can be seen in two of the images below). Also of note is just how "narrow" this horn is; compared to the Radio model in my collection, the outer slide tubes are roughly ½" closer together and the outer tubes of the tuning slide legs are over ¼" closer together.

One interesting feature of the hammered finish is that, while it does not show through to the inside of the bell in the flare area, it does show through on the inside of the neckpipe and bell tail (and likely the tuning slide crook as well, though I don't have the capability to verify that). It's interesting to speculate on what, if any, impact the dimpled finish has on the instrument's acoustics.

When it was first introduced, the Military model was the most expensive trombone in the Olds line; in Chicago Musical Instrument Company's General Catalog Number 35, it is priced at $135 - compared to $120 for the Standard, Self Balancing, and Radio models. The Military could be ordered without the hammered finish for only $120, and the other models could be had with the hammered finish an extra charge of $25. This particular horn dates from the early 1930's and carries two serial numbers; 73xx on the bell section (also marked LM) and 7487 on the slide.

A point of clarification: as far as I've been able to determine, the Military model was not specifically designed or produced for use in military bands. "Military" was simply a model name - used to imply "the exactness and precision of a Military Band" (to quote the description in CMI Catalog #35). Instruments made under contract for the US military would normally have been marked "US". I have seen "US"-marked Olds instruments, but none of the were Military models.

Overall View	Engraving	Bell Rim Engraving Detail	Outer Slide Detail Showing "Stockings"	Bell Braces and Tning Slide
	Slide Braces and Cork Barrels	End Bow	Closeup of "Step" in Outer Slide