20x110HS drill cartridge: M18A2

I have both the M18A1 and M18A3 drill cartridges, so I imagine there must be an A2 out there somewhere? Does anyone have a picture of one or know where to find them? I find the occasional reference to them online, so I’m just assuming that they actually exist.


WRM, this is not the best deal, but if you really want to have it try this auction: gunauction.com/buy/10628817#.

Ouch…thanks for the heads-up (at least I’ve seen one now), but I don’t think I’ll be paying that much for a drill round…especially seeing as how I’d need 5 of them…lol.


WRM, I forgot to mention that there was also a M18 drill, which was the first type introduced in late 1943 or early 1944, but I have never seen one.

The M18A2 looks to perhaps be very similar to the M18A3?

Shown here are the M18A1 Drill on the left, and the M18A3 on the right. Between them is an M21A1 20mm H-S for reference.

Why the significant difference in shoulder position between the M18A1 and M18A3? Are these both for the same gun? Would the M18 be like the M18A1 dimensionally?


I’ve wondered the same thing in regards to the shoulder position. I can only assume that since they’re part of the same series that they’re used in the same gun(s). From the photos I’ve seen of the A2’s, they appear (from looking at a picture…) to be dimensionally identical to the A3’s. I’ve never seen a plain M18 though.


On another note, according to MIL-C-20367G, the M21A1 is simply the designation for the case; not the entire cartridge. There’s also a M21A1B1 out there somewhere. Just for reference, the drawing number for the M21A1 cartridge case is 7553197. The “M18 Dummy or M18A3 Drill cartridges” are specifically called for use in M10 links (M24A1/M3-Type guns) when testing the links for free-hinging or testing the various linking machines per MIL-L-11536D and MIL-B-21341. As of yet, I haven’t found a reference specifically calling for the use of M18A2 dummies.

Dave, I don’t have documentation explaining this, but dummy/drill cartridges are often made this way to prevent deformation of the shoulder after numerous feeding cycles.

The original M18 drill is described in manuals as being the same as the M18A1, except for minor internal details of the body and the base plug (not detailed).



WRM and Fede,

Thank you for the information. I’ll have to pay more attention and keep my eye out for the M18 and M18A2.


I found these pictures online for the M18A2:


[quote=“WRMorrison”]I found these pictures online for the M18A2:

It appears to be dimensionally the same as the M18A3, but with a base more similar to the M18A1 (holes for tooling used to remove the base).


For comparison, here’s the M18A1 and M18A3: