Sean Dempsey said:
The ultra-high speed mechanics of gun functions are fascinating to me.
*clears throat*
Muzzle-loader, Single-shot, Bolt-action, Break-action, Lever, "Normal" Revolver:
- Ignition
- The bullet begins to move due to climbing pressure. Recoil begins in the same instant due to "Equal/Opposite Reactions".
- As the bullet accelerates down the barrel, equal force is applied to both the bullet and the breach face (through the case, when present) by the gas pressure. If the gun was suspended from both ends by strings and was free swinging, the momentums of the bullet+gasses and the gun would MATCH during this process. (Revolvers only: When the bullet passes the cylinder gap a very small, but theoretically there, force is applied to the front face of the cylinder by the gasses escaping through the gap.)
- When the bullet reaches the end of the muzzle, virtually all of the recoil has already been generated. After the bullet clears the muzzle, a (generally smaller, usually MUCH smaller) force is applied to the muzzle crown and breach face by the residual gasses still escaping the barrel.
- Any "recoil" perceived after this point is simply the shooter in the act of slowing the rearward velocity of the firearm and returning it to the ready position.
All
Blowbacks function
similar to above. However, all recoil (except the residual mentioned in #4) is
first transferred to the bolt (excepting some small rearward force applied through friction to the chamber by the case, and some small forward force applied through friction to the barrel by the bullet, the relative size of these forces could be argued forever). As the bolt travels to the rear, a growing amount of force is applied to the receiver by the recoil spring, as well as some force being applied to the receiver through cocking the hammer, if present. When the bolt reaches the rearward stop, all remaining momentum is transferred to the receiver.
Further force is also applied to the receiver as the recoil spring accelerates the bolt forward, and is canceled when the bolt reaches the forward stop. (this is the source of the "lower reciprocating mass is better" arguments)
All
Recoil-operated guns also function
similar to above. However, all recoil (
including #4) is
first transferred to the barrel and slide/bolt (or the "upper frame and cylinder" in automatic revolvers
). As the barrel and slide/bolt travel to the rear a growing amount of force is applied to the receiver by the recoil spring, as well as some force being applied to the receiver through cocking the hammer, if present. Additionally, when the barrel reaches it's rearward stop, the
barrel's momentum is transferred to the receiver. When the slide/bolt reaches the rearward stop, all remaining momentum is transferred to the receiver. Further force is also applied to the receiver as the recoil spring....etc.....etc
All
Gas-operated guns function
the same as above. However, the "reciprocating mass issue" mentioned at the end of the Blowback and Recoil-operated paragraphs is preceded by a force accelerating the
gun forward and the
bolt carrier rearward after the bullet passes the gas port. Some of this force is canceled out during the bolt unlocking process as well as some force being applied to the receiver through cocking the hammer, if present. All the remaining momentum is canceled when the bolt carrier hits the rearward stop. Further force is also applied to the receiver as the recoil ....etc.....etc
THERE! DONE! I didn't mention torque/counter-torques, chain-guns, balanced-actions, recoil boosters, bolt accelerators, elastic vs. inelastic collisions, or a few other things, but it seems relatively complete.
Pardon any errors, I still need to get some caffeine in me.
(i r good at teh mechanics, can i has cookie now?)
EDIT: To clarify, all/most of the various
accelerations happen while the bullet is
in the barrel. Most,
but not all, of the
movement happens
after the bullet has left the barrel. You can spot all the little movements I mentioned in the video General Geoff linked.
