In the mysterious workings of the military bureaucracy, the next version of the McClellan to appear is known as the 1904 model McClellan, although the first ones produced were not made until 1908 (or very late 1907), and they did not completely replace the previous pattern until WWI. Even then, these first M1904’s were M1904(I) saddles (russet) that were altered to the new specifications, before true production of the new model began.
The M1904 Artillery McClellan is a useful study as the artillery saddles were the main subjects of the Ordnance Department’s fine-tuning and revisions of the design. With the formal adoption of the 1912 Cavalry Equipment Board’s Service Saddle, the cavalry McClellan appeared to have reached the end of it’s lifespan. This left the artillery saddles as the only official standard issue McClellan in service*.
Over the course of it’s service life, the M1904 McClellan was consistently altered and revised with small changes and updates. Some were visually significant, some not visible at all, and some suggested revisions that may never have actually been implemented. Rigging changes mirrored the changes of the cavalry version, starting in late 1907. The previous massive singletree hook was replaced by a formed sheet metal version, with a steel rod hook welded to it. It included a iron dee ring of the same pattern as those used on the front arch (see image). This only lasted a very short time, and was simplified to just a dee ring installation less than three years later. A M1904 artillery seat with this singletree hook would be a rare item indeed.
The long-running tradition of heavy brass stirrups used by the artillery came to an end in early 1912, when the M1912 knife-edge stirrup introduced with the cavalry Service Saddle were adopted for the artillery equipment. Service of horse artillery units in Cuba and the Philippines pointed out problems with the iron saddletree parts, and increasing use of bronze for various parts. For a short time, even the iron reinforcement arches used for the saddletree were specified to be heavily copper-plated before painting. Whether this actually happened or not is up for debate.
Around the same time as the stirrup changeover, the stirrup hanger loop was changed to be a solid bronze loop, as part of the effort to reduce corrosion problems in tropical environments. From early 1912 on, all McClellans used these bronze stirrup hangers.