Unusual 45-70 case with F 3-81 or 3-91 headstamp

Hello all,

I picked up the below .45-70 case at a local gun show. It is tinned. The casing is headstamped F 3-91 or 3-81, meaning Frankford Arsenal, made in March of 1881 or 1891. See below. Though it has a primer pocked sized for a standard large rifle primer, it has a groove all the way around near the head. This groove is deeper and all the way around, though it brings to mind the crimp on Benet primed .45-70 cases. The groove is 0.258" from the head of the case, and is approximately 0.05" wide and 0.02" deep. There is also a hole in one side of the groove (shown in one of the pictures). The primer flash-hole measures approximately 0.085" diameter. Any information on this case would be appreciated. Thanks.

The head of the case.

The case from the side, showing the groove and the hole in one side.

My guess is that it’s a dingbat.

groove looks like it was done with a dull knife.

The date is 91, not 81. Frankford Arsenal flash holes in the Boxer-primed .45 rifle cases are typically larger than commercially-made cases of the period. Maybe this was related to the arsenal’s use of the Gill-type primer, or maybe just because it suited them. Jack


.085" for a flash hole is not unusual. The Cal .30 and 7.62mm NATO case drawings, for example, show the flash hole spec as .078" +.004".


Ray: I had a moment to make a quick check of my box full of .45 empties this morning. The toothpick (round type) test showed all four of the FA cases would readily accept the 'pick, while none of the eight or so commercial cases (1870s to about 1910 by WRA, USC, Western, and UMC) would. Jack


That’s interesting. (Normal people would consider us to be certifiably nuts - measuring flash hole sizes with a toothpick) ;-)

I pulled out the drawing for the original Frankford Arsenal smokeless powder Cal .45 case and it shows a flash hole diameter of .1". No min or max, simply .1"

Among shooters, the size of a flash hole is not considered to be a big factor in accuracy (as long as they are uniform). Most of us believe that the length of a flash hole is the critical measurement. I know one 50 BMG shooter who used the 50 BAT M48A1 case without the flash tube and he said it worked just fine. Now that’s a BIG flash hole.


Ray: The toothpick isn’t ideal, but it was at hand. I’ll see if I can get a some kind of a proper measurement of these things. The figure of .1 in. you mention for the flash hole diameter in the FA drawing is interesting, because it does maybe ring a bell. I checked out the FA cases a good while back, and either made no notes or have misplaced them. Jack

Three of the four FA .45-70 cases have flash holes of .1", right on the nose; the last one is a little tighter at .095".