22 scamp

In late 1969 Colt began investigating a possible replacement for the M1911 pistol, one that they hoped to eventually sell to the military. The idea was to develop a completely new weapon, one capable of a high rate of semi-auto or burst fire, lightweight, compact, and accurate, both an offensive and defensive machine pistol. The prototype was dubbed the SCAMP, for Small Caliber Machine Pistol.

To meet the criteria in a high capacity handgun required a small cartridge. Colt considered a variety of existing cartridges ranging from the 5mm rimfire all the way to the 5.56x45. They selected the 221 Remington Fireball as a starting point but even it proved to be too hot, with too much recoil for a machine pistol. They finally settled on a modified 22 Hornet case with a 40 grain bullet. The first cartridges used re-formed Hornet cases and commercial bullets and once the desired ballistics were confirmed a contract was let to IVI for 1000 new cases and bullets. Colt loaded the ammunition which was tested in the sole prototype pistol. Even though the test results were mostly positive the project never moved beyond the prototype stage.

There is much confusion over the SCAMP cartridges primarily because the USAF was investigating a similar concept using their own IMP (Individual Multi Purpose) weapon firing the 221 IMP cartridge, which was an unmodified 221 Fireball. Some of todays Internet sources describe the SCAMP as

That COLT 22 SCAMP is one of my favorite headstamps. I wouldn’t call it rare, just uncommon, and not inexpensive. But if you know the source…;)

What identifies your .22 SCAMP as tracer? It appears identical to my ball round.

Sorry Ray, please disregard my last stupid question! I now see that it’s the .221 IMP which is a tracer.


Very interesting information. On the SCAMP, it’s something to note that the final version was on a rather unique case choice. Perhaps mating case volume for performance and body dia. for magazine capacity? It would seem that, except for the mag. capacity loss, something like a stubby version of the 5.7MMJ would be better for cartridge length for use in a grip fed handgun. Regardless, that’s really cool how they modified a Hornet like that.

On the IMP, is yours headstamped like a commercial .221? And Jim got me looking and I have to ask: How is the IMP identified as a tracer?



Both the 22 MMJ and the 22 Gustafson existed at the time of the SCAMP experiments and I’m sure that Colt considered both of them. Magazine capacity was probably a big consideration because the burst-fire mode would tend to empty a magizine in a hurry. The SCAMP magazine held 27 rounds, I think.

The 221 IMP used the commercial REM-UMC case. There were other IMP cartridges BTW.

How to tell the tracer? As Ronald Reagan said, “Trust but verify.” Trust the guy who told you they are tracers but get a dupe and pull the bullet.


A couple of comments:

The modern-day version of the SCAMP concept is the HK MP7, which has two major advantages over the SCAMP: an extending stock and a forward handgrip. Without those, the SCAMP would have just sprayed bullets all over the landscape.

Another military cartridge has been developed in recent years from the Hornet case: the Czech .17 Libra. This is rimless but is also available in a rimmed version for civilian use. It was designed for a short automatic carbine.