.45 ACP XM261 shot - Tunnel Rat loadings

do you have informations about the XM 261 in 45 ACP
it is used by the rats of tunnels during the Vietnam War.
If you have informations about this cartridge, pictures and data.


The XM261 was an experimental 45 ACP shot cartridge developed for use in Viet Nam. It was loaded with special shot held in a plastic capsule with the general shape of a standard bullet to ensure feeding from a pistol magazine. I believe there were two versions of the capsule itself. I have one of the dark grey ones in my collection and can photograph it for you if you want me to.


this is the picture of the cartridge XM 261


if it is possible I want to have pictures of this cartridge because she is very interresting some answer for a special mission.


This is the XM261 that I have. As far as I know, the only difference is in the shot capsule itself. They are probably of different materials. I belive the cream colored ones were first and the dark gray were later. But I’m no expert on these.


I’m very happy to your send the picture are very beautiful.
do you have data about this cartridge
which firm produced this cartridge
it is possible to have a picture of the base of the cartridge.

I’m happy to oblige.

The total cartridge weight is 245.8 grains

Case length is 22.90 mm

Total cartridge length is 30.73 mm

Made by Western

Below is a photo of the base.


many thanks sir for your help

thanks by a frenchy

I just read a little blurb in the September 1976 issue of American Rifleman (pg 68), by Charles E. Harris which says the following:

Developed experimentally at the Frankford Arsenal under the Personal Defense Weapon (PDW) program. The XM261 was an attempt to increase hit probability of the M1911A1 pistol by firing a quantity of lethal sub-projectiles. Employing such a concept involves several tradeoffs between the number of shot and the desired effective range of the cartridge. The XM261 cartridge was intended to be fired in a smoothbore M1911A1 pistol. Sixteen .147" diameter tungsten alloy spheres weighing 7.5 grains each were loaded in a three-piece plastic sabot, and standard .45ACP case. The wad column featured a plastic obturating base and a steel “pusher plate” to support the shot during in-bore acceleration. Muzzle velocity was approximately 1,100 fps. Other .45ACP experimental shot cartridges based on this design fired nine or twelve .180" tungsten-alloy spheres in a similar loading at somewhat reduced velocity. There have been no plans for further development leading to standardization of these experimental cartridges.

If I remember well the “tunnel rats” was a special force unit that fought against VC inside their tunnel net in the iron triangle area.Am I right?

A bit mad people,but hand grenades and smoke pumped inside the tunnels were not enough to kill the hidden warriors

A part from traps,scarce air and rotten corpses ,shooting a 45 cal pistol into a such restricted place wouldn’t have been very pleasant

I’d like to correct what I believe is an error in one of the answers on this thread, attributing manufacture of one of the XM261 series cartridges to WESTERN Cartridge Co. The cases were made by Western, but the ammunition, “Caliber .45 Hi-Density Shot XM261” was actually loaded by AAI Corporation, according to my box for Lot AAI FAX-45-3203.

Also, there are more differences than just the color of the Sabots, I believe. The AAI loading with the yellowish sabot evidently holds lead shot, as it is non-magnetic. Please note that to test this, you must hold a weak or medium-power magnet at the concave meplat of the sabot, and not farther down on the case, as these rounds have what I believe may be a steel obturator, and below the case mouth react heavily to a magnet. The AAI round does not react to a magnet at the tip of the bullet. However, those rounds rounds with grey sabots, possibly also loaded by AAI although I have no documentation for that (they are also loaded in nickeled cases bearing WRA and W-W headstamps and have the same deep cannelure right below the case mouth as the earlier AAI round) attract a magnet at the tip of the bullet, indicating they are loaded with steel shot (Mallory balls?).

The Franford Arsenal version, loaded with a milky yellowish/white sabot and also having the smooth cannelure right below the case mouth, is in a steel case headstamped F A 53, and also attracts a weak magnet at the tip of the bullet, and since I am using a medium strength magnet held with only the very tip of its corner on the very tip of the sabot, I am fairly confident it is not the steel case and/or obturator that is attracting the magnet, but rather the contents of the sabot.

I have another round with a nylon sabot, dark grey in color but with a much blunter ogive, giving a very wide, flat meplat, that does not take a magnet at the tip. It is loaded in a brass, factory-primed case with headstamp “W C C 7 3.” Does anyone know if this is the XM668 Caliber .45 Lead Shot round loaded by Ensure Munition?

Frankford Arsenal also loaded a flechette round, but I am told it does not have the cannelure around the case mouth. Can anyone confirm that?

Edited to change “WESTERN” (an error) to “WRA” which is one of the two correct headstamps for the rounds I referenced.