Welcome to M1911.ORG
The M1911 Pistols Organization Forums Site


John needs your help
Please read this message.


Sponsors Panel
If you intend to buy something from the companies advertising above, or near the bottom of our pages, please use their banners in our sites. Whatever you buy from them, using those banners, gives us a small commission, which helps us keep these sites alive. You still pay the normal price, our commission comes from their profit, so you have nothing to lose, while we have something to gain. Your help is appreciated.
If you want to become a sponsor and see your banner in the above panel, click here to contact us.

Results 1 to 4 of 4

Thread: Recoil Operation of the 1911

THREAD CLOSED
This is an old thread. You can't post a reply in it. It is left here for historical reasons.Why don't you create a new thread instead?
  1. #1
    Join Date
    1st June 2004
    Location
    Lexington, North Carolina...or
    Posts
    11,260
    Posts liked by others
    29

    Recoil Operation of the 1911

    Jerry Kuhnhausen mentions a Balanced Thrust Vector in his description of the 1911's operation. Some knowledgeable folk have studied this, and come to the conclusion that he doesn't understand how the Browning short recoil system works. I think Kuhnhausen fully understands it. He just didn't convey it clearly. Here it is, in simpler terms.

    One thing to bear in mind is that the 1911 pistol isn't a true locked-breech weapon in the strictest sense of the term...like a bolt-action or single-shot rifle. It doesn't actually lock until it's fired, and then it's locked by pressure...the vector of thrust generated by expanding gasses in the chamber and barrel. At that point...it locks up while the pressure literally tries to rip the locking lugs off the barrel and out of the slide while it forces the bullet through the bore.

    Slide in battery...Lugs meshed together. (If we're lucky, or have a correctly fitted barrel, all three lugs are bearing an equal share of the load in the horizontal plane and we have full...or nearly full...depth of engagement and lug overlap in the vertical. Very few production guns achieve this ideal. (An important consideration if one is considering one of the souped-up, drop-in conversions based on the .45 ACP case. The less lug engagement you have in either plane, the weaker the lockup.)

    The round fires. The bullet is forced down the bore under pressure. The same pressure drives the slide backward in Newton's "Equal and Opposite" function. The barrel is held fast by the frictional resistance of the bullet while the slide is trying to pull it backward via its connection of the locking lugs. For a nanosecond, there is equilibrium...or the balanced thrust that Kuhnhausen mentions...but this doesn't last long.

    The slide, due to its greater mass, conserves a greater amount of momentum from the thrust generated by the expanding gasses, while the bullet...obeying Newton's other law stating that Objects in motion tend to remain in motion...requires less force to keep it moving...and the faster it moves, the less it requires. The slide, with its greater mass and conservation of momentum, gradually overcomes the mass of the barrel and bullet and starts to pull them backward toward the unlocking point. It's winning the tug of war that began when the round fired. The bullet is still in transition at this point, and hasn't exited the muzzle yet.

    The barrel's unlocking phase BEGINS at .100 inch (nominally) of slide movement. At some point prior to that...in a correctly timed gun...the bullet exits and pressure falls off to nearly zero. All of a sudden, the heavy slide, with all that conserved momentum, is freed from the restraint of the barrel's mass, and the bullet's mass and friction...and it slams rearward to complete the recoil phase of the cycle. The restraining factors are: Friction...The recoil spring's load and rate of loading. The hammer's inertial mass and friction against the disconnector rail after rebounding...The mainspring's loading...and the resistance of the disconnector via the sear spring. The slide conserved all the momentum needed to complete the recoil cycle in less than .100 inch of movement. Once the bullet exits, there is no more to be gained.

    At the end of the recoil phase, the recoil spring's stored energy sends the slide back to square one, stripping and chambering the next round from the magazine on the way. If the magazine is up to the task of lifting the next round into correct feeding position, the round feeds. If the magazine's spring is too weak to do the job...slow magazine timing...the slide either rides over the round and produces a cmplete failure to feed... or catches it in the extractor groove, producing a Bolt-Over-Base type feed that is actually a live-round stovepipe with the round standing straight up, or nearly so...caught between the slide and the barrel hood.

    Note that "Failure to Feed" is often used to describe what is actually a failure to go to battery. A true failure to feed means that the round doesn't enter the chamber. If it gets into the chamber...if only part-way...it's not a failure to feed. It fed...It just didn't chamber completely and go into battery. Both the above malfunctions are true failures to feed, though sometimes the Bolt-over/Live Stovepipe does get under the barrel hood.

    Note also that "Timing" is often mistakenly used when describing the slide's cycle time. The two are very different. Cycle time is controlled and dictated by recoil spring load and rating and varies with spring loading and the amount of compression of the spring at a given point in the slide's position, while timing is mechanical and fixed. You can remove the recoil spring from the gun and fire it...and the barrel unlock timing will remain the same...because it unlocks at a fixed point, controlled by the specs of the lower barrel lug and the length of the link. Use a longer link, and unlock timing is delayed. use a shorter link...along with a little reshaping of the lower lug...and it advances. This is why playing with different links without a full understanding of what occurs can get one into expensive damage or even dangerous zones.

    Magazine timing is controlled by the spring alone...assuming that there isn't a physical barrier within the magazine body that holds up the round's rise. If the magazine is clean and in-spec, the friction within can be, for the most part, ignored. Magazine timing varies as the magazine empties, which is why it's necessary to have enough spring to lift the last round...while the tension is at a minimum...and still avoid having so much tension that the slide can't strip the top round...when it's at maximum... and still provide enough oomph to complete the chambering phase. It's a balance.

    In the chambering/return to battery phase, the round strikes to upper portion of the feed ramp and deflects upward into the middle portion of the barrel throat. (Actually, the barrel's throat is the leade ahead of the chamber shoulder. Often used to describe the barrel's ramp...but we'll call it the throat to avoid confusion.)

    The barrel throat deflects the round a little higher so that the top front portion of the bullet strikes the roof of the chamber...just under the barrel hood. While all this is going on, the rim is forcing its way under the extractor hook, aided by the round trying to break over to horizontal, and by the magazine spring pushing upward on the butt-end of the round. The two act together to effect the controlled feed that the gun was designed to do. In this...due to the last round's minimal spring tension...
    the magazine has a release point in which the round is freed from the feed lips
    entirely. This is known as the "Release Timing" and is critical to provide a true controlled feed, especially with the last round. If the cartridge releases too early or too abruptly, it gets ahead of the correct feeding position and the extractor. The result is very often a push-feed, where the round is literally pushed into the chamber by the nose of the extractor instead of being guided in under full control
    offered by the extractor, the barrel throat, and the chamber hood. Simply put, the cartridge is supposed to be completely captive from the time the slide hits it until the empty case is ejected. If it gets loose...even for a split second...even if the gun functions...it's essentially a malfunction. That it doesn't lead to a stoppage doesn't change that one iota.

    Whew! El Commandante'...You may stick if you wish.
    Last edited by 1911Tuner; 14th September 2005 at 15:03.


  2. #2
    Join Date
    8th March 2006
    Posts
    372
    Posts liked by others
    0
    "all three lugs are bearing an equal share of the load in the horizontal plane"
    Three lugs? Two on top of barrel and a pair of lower lugs makes four?

  3. #3
    Join Date
    29th May 2004
    Location
    Athens, Greece, Earth
    Posts
    28,076
    Posts liked by others
    204
    Blog Entries
    2
    Three on top of the barrel.
    John Caradimas SV1CEC
    The M1911 Pistols Organization
    http://www.m1911.org

  4. #4
    Join Date
    1st June 2004
    Location
    Lexington, North Carolina...or
    Posts
    11,260
    Posts liked by others
    29

    1Lug 2Lugs, 3Lugs Four

    The locking lugs are what I was referring to as the lower barrel lug doesn't
    bear up against the forces of firing/recoil.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  



Sponsors Panel
If you intend to buy something from Brownells, please use their banners above. Whatever you buy from them, gives us a small commission, which helps us keep these sites alive. You still pay the normal price, our commission comes from their profit, so you have nothing to lose, while we have something to gain. Your help is appreciated.
If you want to become a sponsor and see your banner in the above panel, click here to contact us.

Non-gun-related supporters.
Thank you for visiting our supporters.