OK, so I'm sure there are some mechanical engineers and physicists on this forum so here's my question: Is there a standard measurement for recoil? If so, is it in Joules, Ft/lbs, PSI? And would an air compressor have sufficient power to replicate the recoil impulse in a dummy gun?

I'm not sure about measurements, but we had tethered Glocks for our FATS system. The slides operated on compressed air.

The TiTraining use of force training system mostly uses dummy magazines and CO2 cartridges to cycle the slide, thereby simulating the recoil and to reset the hammer or striker for subsequent shots. There were also tethered adapters using hoses to a remote CO2 source for guns whose magazines were too small/narrow to accommodate the cartridges. The “recoil” is less than when firing a real cartridge, but better than nothing which was the case with early systems.

In the US all the recoil figures I’ve seen have been in foot-pounds; in Europe and elsewhere I would assume the values are in joules.

I'd like to know what project you're working on!

A shop-sized air compressor should operate most any pistol slide, with adequate seals. I'm not a physicist, so I'm not sure how you'd measure the "force" of it. I'm sure someone smarter than I has invented a contraption to do just that. As you probably know, American spring weights are measured in pounds. And coil springs "stack". The more they compress, the "heavier" they get. I don't know this for a fact, but I'd expect a "15 pound" recoil spring to be able to support "15 pounds" of pressure at full compression. I doubt that helps, but I wish you luck in your experiments.

There are a couple of aspects to recoil.

First, recoil is a measure of momentum, which is conserved – absolutely. Momentum is MV – mass * velocity. So mass of the bullet, and exhaust gases times muzzle velocity of the bullet and the integral of the exhaust gas velocity is the momentum. That is recoil.

Then there is “impulse”. impulse is force * time, and impulse is always numerically identical to momentum.

Two pistols, with the same muzzle length, firing the same ammo, will have the same recoil (momentum), and the same impulse. But the force and time components of impulse can differ. A blowback pistol will generally have a higher force value and a smaller time value than a locked breech pistol. Consequently, the blowback pistol will be perceived to have a sharper recoil than the locked breech pistol, even though both have the same recoil, by momentum and impulse values.

This guy has a couple of videos on recoil measurement.

Basically I'm trying to figure out if there is some way of simulating recoil of standard pressure and +P rounds in your own firearm through the use of compressed air. To do this somewhat scientifically, I would need to have a quantifiable measure of force caused by the slide slamming into the frame in full recoil by an actual round being fired before I can replicate it with compressed air.