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Discussion in 'Gunsmithing and Repairs' started by ken grant, Jan 12, 2005.

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  1. ken grant

    ken grant Well-Known Member

    It is amazing how such a little change can make such a big difference in the feel of recoil in a 1911. :what: :D
    For the first time today, I shot both a Colt Combat Commander and a Norinco Compact at the same range session. The Norinco seemed to have much less recoil than the Colt and didn't rise as much on firing.
    The only difference in the pistols were the firing pin stops. The Colt had the stock stop in it and the Norinco had a stop 1911 Tuner had put in(oversized) with a very little radius on the bottom.
    I plan on fitting stops to all my 1911's with the small radius on the bottom. It really makes a difference in recoil feel. :D
  2. 1911Tuner

    1911Tuner Moderator Emeritus

    Viva la Differance'

    Ken! Shhhhhh! Don't be givin' away my secrets now... :uhoh:

    Wait! Nix that. :scrutiny: John Browning figgered that radius out dang nigh a hundred years ago... :rolleyes:

    I guess old John Moses really did know his bidness... :cool:
  3. R.H. Lee

    R.H. Lee Well-Known Member

    ken- would it be possible for you to post photos of each firing pin stop side by side?

    Thanks. :)
  4. Old Fuff

    Old Fuff Well-Known Member

    Why Tuner ...

    How can you be so easily fooled ??? This is something that the New School folks don't use, and is therefore hopelessly obsolete ... :neener: :D
  5. R.H. Lee

    R.H. Lee Well-Known Member

    Fuff has a point. Unless it is properly endorsed by a real Pistolsmith (tm), it may be a questionable practice.
  6. 1911Tuner

    1911Tuner Moderator Emeritus


    Ken...I fear that you have awakened a sleeping giant. You've probably just
    sold about 2,000 EGW firing pin stops with one stroke of the keyboard.
    George oughta give you a kickback...or at least a discount on a few of the things. :p

    Riley...The standard stop has a 7/32nd inch radius. The original...like Ken has...was/is .075-.080 inch, with .078 bein' print spec.

    Fuff...I just never took any of the new-fangled stuff too seriously I reckon. I gave myself a headache makin' a handful of the old design stops...and then 20 years later along comes EGW with the dang things semi-finished and oversized to boot...for 10 bucks a copy! (They're about 20 now)

    Now then...I'll leave it to ya'll to figger out WHY it has that effect. :neener:
    Keenan and Fuff know why. Thinkin' caps on and....GO!
  7. R.H. Lee

    R.H. Lee Well-Known Member

    Well, you see, the lower end of the firing pin stop is the part that contacts and pushes back the hammer on recoil. When it's radiused, it makes for a smoother, more even rearward movement of the slide, because the hammer begins to move sooner.
  8. 1911Tuner

    1911Tuner Moderator Emeritus

    Why ask Why

    Riley said:

    > a smoother, more even rearward movement of the slide, because the hammer begins to move sooner.<

    Nope! You're thinkin' about it backward.


    The smaller radius actually causes the hammer to move more abruptly...once it starts. :scrutiny:
  9. R.H. Lee

    R.H. Lee Well-Known Member

    oh yeah.....

    Well, ya can see I ain't no Pistolsmith. :p
  10. 1911Tuner

    1911Tuner Moderator Emeritus

    Osay Can U C?

    Riley said:

    Well, ya can see I ain't no Pistolsmith.

    Hey! Me neither! :D
  11. R.H. Lee

    R.H. Lee Well-Known Member

    OK Tuner, since you're not going to 'splain it (at least right away), I'll give it another shot. Since the hammer begins to move later rather than sooner, the felt recoil is reduced because........??? the time the pistol is in recoil is shortened?

    Why does this stuff make my head hurt?
  12. Black Snowman

    Black Snowman Well-Known Member

    Does it have to do with the lock time being extended by additional force required by the slide to get moving with the leverage being closer to the fulcrum of the hammer?

    The bullet and gas has progressed down the barrel longer before the slide starts moving imparting more energy to the heavier mass of the gun and frame. When the slide does start moving it has a lower velocity so when it reaches the full back position it hits the frame with less force. So, the recoil impulse is spread out with more initially and less at the end of the cycle reducing muzzle flip and felt recoil.

    Or something like that.

    That should be close right?

    Edit: I might be cheating though because I researched this before buying my Delta Elite ;) Mostly here: http://www.geocities.com/mr_motorhead/10tech.html
  13. Old Fuff

    Old Fuff Well-Known Member

    Tuner ...

    You still ain't got it ...

    To be a "piss-to'l 'smith you have to be a PROFESSIONAL ... :neener:

    The reason that firing pin stop works is because it's the way John Browning designed it. Unfortunately someone in the Army decided it should be changed. Things haven't been right since. :fire: :mad: :D
  14. ClarkEMyers

    ClarkEMyers Well-Known Member

    Anybody have high speed pictures?

    There's a lovely discussion by some very smart people on another board with interesting thoughts - including talking about how nice it would be to have pictures - anybody have references to controlled tests with observed distinctions?

    Of course as some have said comparing recoil in a 1911 across different shooters can be a waste - Layne Simpson reported trying to do a controlled test of ports and compensators with friction on a Ransom Rest and not getting anyplace.
  15. Black Snowman

    Black Snowman Well-Known Member

    Don't let them get your goat 'Tuner (I know you won't anyway). Professional doesn't mean you're any good. Just means you're paid for it. ;)

    To steal a member's sig line I saw a while back: Professionals built and operated the Titanic. Amatures built and sailed the Arc. :neener:
  16. 1911Tuner

    1911Tuner Moderator Emeritus


    The Black Snowman nailed it square on the hittin' place!

    The smaller radius decreases the slide's mechanical advantage in cocking the hammer. The slide is delayed for a fraction of a nanosecond, and bleeds off
    a good bit of the recoil impetus. The slide moves a little slower and with less force, and softens the blow to the frame...quite a bit, as Ken noted.

    Also...Since the slide's delay gives the chamber pressure a tick longer to fall off, the extractor doesn't have to work as hard to break the casing's grip on the chamber walls during primary extraction...and in some instances will actually allow surprisingly reliable function with the extractor removed. Other things contribute to that little trick...but I've seen some pistols that wouldn't quite do it...until the firing pin stop radius was reduced...and it pushed'em over the edge.

    The small radius utilizes more of the mainspring's resistance to hammer movement...and allows the use of lighter recoil springs with little or no reduction in frame protection. So there you have it...The original, Browning-designed shock buffer...and it doesn't shred or fall apart every thousand rounds. :p
  17. R.H. Lee

    R.H. Lee Well-Known Member

    Brilliant! I actually understood that explanation. Thanks, Tuner :)
  18. Shootcraps

    Shootcraps Well-Known Member

    So how can we purchase these parts?? Or do they have to be fitted?
  19. 1911Tuner

    1911Tuner Moderator Emeritus


    Clark made a good point, and spot on. Give 5 people the same gun and ammo, and all will report different recoil impressions. A side-by-side test,
    like Ken's experience can be revealing though. Even better is to change only the stops in the same gun. The difference is real, and depending on the
    mainspring and recoil spring load, it can make quite a noticeable difference.

    Looky at what you started Ken! A genuine discussion! Kudos lad...Kudos! :cool:
  20. Snake Eyes

    Snake Eyes Well-Known Member

    Amazing. This is exactly what Ted Yost is doing to my Delta Elite, to keep the slide from beating the frame to death.

    Just amazing what a quality oriented 'smith can come up with to actually solve little issues like this.

    I think Ted has headspacing gauges too!
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