So, how hard does the slide hit the frame? It seems to the one of the big concerns.
Let’s do a little math.
Assuming a 230 grain bullet at 830 fps…GI Hardball spec…we’ll calculate the slide’s speed and kinetic energy. Weights were taken on a postal scale using a 1919 production Colt GI pistol. Due to better modern steels, those weights may vary a little.
The slide and barrel assembly weigh 16.8 ounces, or 7350 grains, while the slide weighs 13.8 ounces or 6057 grains. During initial firing, the slide and barrel move as a unit, so their combined weights are used to calculate the slide’s speed.
For this calculation, we won’t consider the effects of the recoil spring, hammer mass, mainspring, or any friction between the slide and frame.
At 7350 grains, the slide’s mass/weight is close enough to 32 times that of the bullet to call it 32. That means that the slide’s rate of acceleration and final speed at the bullet exit is 1/32nd that of the bullet’s. Once the bullet has left the muzzle, no further acceleration of the slide is possible. The slide and barrel assembly are moving as fast as they ever will.
Now, we have 7350 grains of mass moving at 1/32nd of 830 fps. That works out to 25.9 fps..or close enough to 26 to call it.
A quarter inch into the slide’s trip, the barrel falls away, leaving the slide to continue on its journey to the frame impact abutment. 6057 grains are moving at 26 fps.
I pulled up an online bullet energy calculator…because those use grains…and plugged in the numbers.
The slide, moving 26 fps, carries 9 foot-pounds of kinetic energy, which means 9 foot-pounds of impact energy.
I’m going to assume a 14 pound recoil spring and a 23 pound mainspring along with a wide spur hammer…Browning’s original specs.
If we then factor in the effects of the springs, hammer mass, and what little friction that exists…a rough estimate brings the slide’s impact velocity down to around 22 fps, or maybe even less. I’ll be generous and call it 22. Now, the kinetic energy is down to around 7 foot pounds.
Seven foot pounds.
To put that into perspective, the standard velocity .22 Short…32 grains/1000fps..carries 70 foot pounds of kinetic energy.
Not exactly the hammer of Thor, now is it? Surely not enough to beat up the frame, as is often claimed by the heavy spring and shock buff proponents. The gun just isn’t that fragile.