VARIATIONS IN EARLY WARTIME 1928A1 BOLTS
I think that most of us with wartime Thompsons, particularly those of us with 1928A1 models, believe that our guns parts are the models "correct" parts, and further, that the parts are all the same from gun to gun (except for barrel and rear sight). I was surprised to find that thats not necessarily so. Recently, I disassembled and examined a batch of twenty-one Thompson 1928A1 bolt assemblies from early War guns. These were the rare "bright bolt" variety with knurled actuators. The "bright bolt" identification is, in itself, a bit of a mystery, since we have heard that they were nickel steel, like the Colts. Upon close inspection, however, I believe that the material was nickel-plated ordnance steel, because all the bolts had some black "stains" from wear or old solvents, which appears to be like plating being worn off or chemically damaged. These assemblies were from "British" guns, but that could mean England or any of the Commonwealth countries. In these 21 sets, I found 4 bolts marked "R", which is presumably Remington (on behalf of AO ? or Savage ? your ideas ?). These "Remington" bolts have different machining versus the Savage bolts in the extractor cuts. A Savage bolts extractor slot has two circular tool entry marks (looks like drill marks but are flat, so are milling machine marks), one at each end of the cut. The Remington extractor slots had a third tool entry mark midway through, where the cut goes from wide to narrow. All bolts, except for a very special Savage, had a tiny, faint "P" on the left side of the bolt, which I presume is an inspectors mark (perhaps "P" for "proof?). Thus, the "special" bolt clearly came from a different batch or even from a different country (more about it later).
Of the 21 actuators, 2 were "R" marked and the manufacturing appears identical to the Savage actuators, the knurling is the same 6 by 5 diamond pattern and the side slots appeared to be machined the same. Surprisingly, there was considerable variation among the Savage actuators as to the height and rim thickness of the stem portion, that is, the base of the round knob portion. Of the Savage actuators, all but a couple had parallel line marks on the spring hole end. I call them "parallel lines" because I theorize that they were an inspectors marks, apparently made by hitting two strikes with an "I". I have a variety of styles: "II", two long lines (letter length), two middle-sized lines, and two short lines. I know that it sounds a little crazy, but my impression was that the inspectors stamp (his mark) was gradually wearing down and he never got around to getting a new one. (I would welcome competing theories.) The Remington bolts had no such marks.
The treasure in the bunch, the "very special" Savage bolt, was something that Doug Richardson speculated about in one of his articles: a 1928A1 bolt with a second (backend) safety cut out on the bolts bottom just like the M1A1s bolt (which allows the safety to be switched "on" with bolt forward). Doug was saying that this approach would have made sense from the 1928A1s safety standpoint, but made no reference to having actually seen one. This machining on this safety cut out is obviously NOT from a milling machine, for the shallow end has a slight rounding and the deep end is not a true perpendicular to the bolt shaft. I speculate that a Depot did this for a paratroopers gun, or, that the trooper did it himself. In either event, what a lucky find!
Contributed by Chris Martin.