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understanding p89 barrel lockup

This is a discussion on understanding p89 barrel lockup within the Gunsmithing forums, part of the Firearm Forum category; can anyone help me understand the lockup and timing of the P series swinging link series pistols? I have a pretty good understanding of 1911 ...


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Old November 28th, 2016, 09:05 AM   #1
 
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understanding p89 barrel lockup

can anyone help me understand the lockup and timing of the P series swinging link series pistols?

I have a pretty good understanding of 1911 barrel locking but the P series is confusing me. The P series does not seem to have a VIS area on the frame like a typical browning tilting barrel design.

what I am trying to do is get a visualization of the locking/unlocking process that goes on when a round is fired.

Nice forum by the way. I have learned a lot in general about the P series through others experiences. Longtime lurker.



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Old November 28th, 2016, 10:18 AM   #2
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david vincent, A P89 works exactly like the Browning patent on a 1911. The difference is .... a 1911 barrel and slide have lock lugs whereas the P89 uses the rear squared section of the barrel to lock into the slide.

Timing sequence: Trigger is squeezed until the sear releases the hammer then gets disconnected from the sear. The hammer thrusts forward and strikes the firing pin and in turn, the firing pin strikes and ignites the primer. Once powder starts burning, chamber pressure will increase dramatically causing the bullet to emerge from the case and accelerate very quickly until it exits the muzzle. Pressure inside the barrel will drop until the slide releases the barrel. Residual barrel pressure pushes the spent case and slide fully to the rear until the spent case strikes the ejector and is flung from the ejection port. The slide will then move forward powered by tension from the recoil spring. Along the way, the lower edge of the slide will strip the top round from the magazine. As the slide continues forward, the head of the fresh round will slide into position on the breech face and allow the cartridge to chamber. When the slide reaches full battery, the barrel will pop up and lock into the slide. When the trigger is released, the disconnector will reposition on the sear, making it ready to fire the next round.
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Old November 28th, 2016, 11:43 AM   #3
 
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right. I get the barrel locking lugs into the slide. Where I am a little confused is the lower Lug beneath the barrel (part that holds the link pin). On a 1911 the barrel moves down at a 40 degree angle where it makes contact with the vertical impact surface (VIS). Now on something like say a P89 there is no VIS that I can see. So where is the pressure being put. surely its not put on just the slide stop pin, link, and lower lug slide stop pin recess.



I looked pretty hard for an example of a graphic generated visual on the net showing the process in action like you see for 1911s but came up short. people dont seem that interested in P series guns like they do 1911s' glocks, sigs etc.

just trying get a feel for whats going on internally regarding the movement of the barrel and where the forces are being distributed.

I have a few of these P series guns and multiple uppers and parts. something like a 1911 you dont dare just slap another upper on it without checking barrel fit to the frame. Now I know folks here do it on P series guns but I want to know a little more about the dynamics and areas that could possibly be affected.

I also see people throw decocker uppers on safety model frames and get away with it. Not sure about that either as they use a different hammer. The rest of the parts between the Decocker models and safety models appear to be the same on a quick look. Thats probably best left to another thread though.
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Old November 29th, 2016, 02:18 AM   #4
 
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Quote:
Originally Posted by david vincent View Post
right. I get the barrel locking lugs into the slide. Where I am a little confused is the lower Lug beneath the barrel (part that holds the link pin). On a 1911 the barrel moves down at a 40 degree angle where it makes contact with the vertical impact surface (VIS). Now on something like say a P89 there is no VIS that I can see. So where is the pressure being put. surely its not put on just the slide stop pin, link, and lower lug slide stop pin recess.



I looked pretty hard for an example of a graphic generated visual on the net showing the process in action like you see for 1911s but came up short. people dont seem that interested in P series guns like they do 1911s' glocks, sigs etc.

just trying get a feel for whats going on internally regarding the movement of the barrel and where the forces are being distributed.

I have a few of these P series guns and multiple uppers and parts. something like a 1911 you dont dare just slap another upper on it without checking barrel fit to the frame. Now I know folks here do it on P series guns but I want to know a little more about the dynamics and areas that could possibly be affected.

I also see people throw decocker uppers on safety model frames and get away with it. Not sure about that either as they use a different hammer. The rest of the parts between the Decocker models and safety models appear to be the same on a quick look. Thats probably best left to another thread though.
To see how the barrel functions, real simple remove the slide. Insert the barrel and link in the frame with the slide stop pin inserted in the link through the frame. When you hold the barrel just forward enough so the link is just past vertical, which should be the barrel/slide lock up point. Now slide it reward until it rests in the frame. That will show you where the barrel will rest when ejection/loading occurs. Frame to barrel fit is not as difficult when the barrel slide lock setup is the Sig type setup used by Ruger, Glock etc. now days. The old Browning slide /frame lugs have more fit issues, but its 1911ís, BHP's, and CZ's that are most prevalent to that now days.
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Old November 29th, 2016, 11:45 AM   #5
 
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yeah it looks like all the force is transmitted down into the frame and on the link in conjunction with the slide stop and side of the frame in the holes for the SS. its a little different than a 1911 which puts the stress more on the vertical impact Surface and along the upper portion of the bottom barrel lug. I think i get it though. certainly make barrel swapping an easier task. No real fitting involved in that area from what i can tell.

I think the best thing for me to do at this point is put some prussian blue and different areas and cycle a bunch of dummy rounds through the gun to see where the contact is being made.

Now my next issue I have not been able to figure out. This in regards to the switching of uppers from safety to decock or vice versa. I am looking at two p89s. one is a decock and the other is a safety model. Same generation guns. Most of the parts look the same but the hammers are definitely cut differently. The decocker hammer has a bit of a different shape where the sear interaction occurs (I think anyways...tough to see). does anyone know why the difference in hammers from safety to decock versions? I am a little reluctant to swap uppers before I understand this. When doing function testing everything appears to work the same but I must be missing something.
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