View Single Post
Old April 24, 2012, 06:16 AM   #22
B.L.E.
Senior Member
 
Join Date: December 20, 2008
Location: Somewhere on the Southern shore of Lake Travis, TX
Posts: 2,603
Quote:
Originally Posted by JohnKSa
Slide velocity is affected by a number of variables, the primary ones being the weight of the recoiling mass (slide/barrel combination in the case of a typical locked breech semi-auto pistol) and the muzzle momentum of the load being shot. The recoil spring must have some effect since it exerts a force opposite the recoil momentum. Exactly how much effect it has depends on the design of the firearm the strength of the recoil spring, how much compression it's under when installed, etc.
Yes, of course it has some effect, just like hitting a bug with my windshield has some effect in slowing down my car.

Consider the forces on the breech during bullet acceleration. A .45 ACP has a standard pressure of 21,000 psi. The base of a .452 diameter bullet has 0.16 square inches of area. 21,000 pounds/square inch X 0.16 square inch = 3360 pounds of force on the base of the bullet and exactly 3360 pounds of force exerted backwards on the breech. A spring strong enough to significantly interfere with the rearward acceleration of the slide and barrel during bullet acceleration would be so strong that Rambo couldn't pull the slide back to cock the gun.

What the spring does is absorb the kinetic energy of the slide as the slide moves backwards after the pressure is gone. The problem is, a spring that absorbs energy during compression also gives that energy back when it decompresses, so a spring that's strong enough to totally prevent the rearward hammering as the slide reaches its stop will hammer the slide as the breech closes again, perhaps hard enough to cause the inertia of the firing pin to slam-fire the round.
Unless, we can invent a 20 pound spring that magically becomes a 5 pound spring when it returns the slide.
B.L.E. is offline  
 
Page generated in 0.03280 seconds with 8 queries