1911 FP stop drop

[RsqVet]

I had this one happen to me today. New project gun, was not expecting that one.

Subject gun is a 90's colt officers model. Gun has had work on it by 2 prior smiths. High quality work. Fp stop appears to be OEM colt slightly loose but not unusual for colts I have worked on relative to a custom / semi custom gun.

I bought this gun figuring it would need a few things, already had to source a new spring for the kings guide rod and it needs a plunger tube.

I plan to fit a new square profile fp stop anyway, there may be slight ejector clocking as well so its no huge deal to replace this, extractor likely as well for the fun of it. Of course a new fp spring. Anything else to address?

Other than the above gun ran great, even held as limp wristed as I dared. Impressed for an officers gun. Gun has had the melt treatment and feels great.

[DnPRK]

An EGW-Guns oversized FP stop is a good way to solve looseness and extractor clocking

[RsqVet]

EGW is who I planned to go with. Gradually have been putting square profile stops on all my guns, either EGW or Wilson depending upon what other parts I need

[James K]

It takes a combination of factors to do that, usually involving hot loads and a light mainspring. When the round is fired, the slide moves back rapidly and kicks the hammer, hard. That causes the hammer to move back on its own, out of contact with the slide. Meantime, the firing pin is still forward as the gun recoils upward. Since the firing pin is not retaining the firing pin stop, it stays in place as the gun recoils, so it moves downward in relation to the slide, moving into the space left when the hammer moved back and down away from the slide.

Of course, none of this shows on those neat drawings we see in the books of the slide gently pushing the hammer back and all the parts performing a graceful ballet instead of the slamming, banging, and beating that actually goes on when the gun is fired.

Jim

[RickB]

That's especially true if the hammer, at rest, contacts the firing pin stop above the firing pin, as is often the case.
The shape of the heel of the FPS won't matter unless the contact point on the FPS is down at the bottom.
I've seen some FPSs given a custom wedge shape, to ensure that the contact point is at the bottom.

[RsqVet]

Rick thanks for the pointer, I will check on that as I am fitting mine.

James -- I appreciate the input, you are correct, lots more slamming than those neat cartoons.

Loads were just factory (federal) 230 ball and a few HST. Spring is 22 # flat wire. But yes It is an officers 1911 so a a rather violent cycle.

I guess it's a lesson learned, I have read about it, even seen the stops with with set screw to prevent it, never had it happen so was not on the radar as a priority. Once is enough, tight slide stops have moved up the list from a get to it on various project goes to more of an imperative.

[James K]

I never had it happen until I started working up some "warm" (OK, hot as Hades) loads for pin shooting.

I never had a problem with thousands of GI and GI spec loads in the same gun.

Jim

[HiBC]

I'm not a 1911 ghuru,and I have no experience with the compacts...

I do get little newsy e-mails from Wilson Combat.

One of them addressed compact 1911 compacts.

Two things I took away:

They have,and recommend,a square wire spring.Maybe a sales pitch,maybe worthwhile.Up to you.

The main thing,they recommended against 230 gr bullets in the compacts,along with +P.

Mr Wilson said he recommends and carries 185 gr HP's in his.Its got to do with the recoil pulse and functioning.

On the square lower edge:

My opinion based observation,take it for what its worth.I was requested to install one on a 460 Rowland project.

I was told the original JMB design was the square corner.
Allegedly it was rounded to make hammer down slide racking on the back of a horse easier.I don't know for sure,that was part of the sales pitch I was given.

A higher rate mainspring was also requested.

The idea was ,between the change in geometry(shortening the hammer lever arm) and increasing the mainspring rate,the hammer was being used to delay slide motion to the rear,delaying unlock.

OK,maybe.I do not argue with the principle.However,I do have my concerns.

Moving the hammer/slide contact point down closer to the hammer pin (center of rotation) greatle accelerates the hammers rearward motion.Probably,it smacks the grip safety,then bounces back.Not sure how good that is.

The other concern,the hammer pin and the holes in the frame were hired to hold the hammer.Inceasing their workload by giving them the additional duty of locking the breech....hmmm.I have no tests or data,and I'm not an engineer.IMO,generally,components are engineered to be adequate,but not overkill.Hotrodding requires a comprehensive look at a whole system.

So,I would have concerns about the hammer pin and the holes in the frame,particularly if alloy frame.

Maybe I worry too much.But you can at least think about it.

[RsqVet]

HiBC ---

Thanks for the input, more ideas are always welcome.

I agree that Wilson combat knows their stuff. The free help I have gotten from their customer service has been priceless at times with minor fit / function questions.

I have known the officer is a another beast as Brown and Baer refuse to make them, Wilson and Nighthawk used to but stopped due to too many returns. I am still looking at this as an experiment, I love the size of the gun for packing. If quality and reliability is there or can be made to be there then why not?

The gun has the 22 pound flat wire wilson spring in it. I plan to add a buffer if the gun slingshots still with one in it though I am not a buffer guy otherwise.

So far I like the flat wire spring, plan to try one in a full size sometime.

No plus P for the officers though if I can not toss my normally stocked 230 gr JHP's in it then it has lost a lot of it's appeal. I will consider that a last sort if nothing else works...

As the gun is older it will get a new mainspring as part of the detail strip / clean just because....

I have liked the square slide stops in full size and commander guns I have put them in.

I see what you are saying with the square stop however my understanding is is it is just a slight change, the gun does not stay locked some huge amount of time longer. The sight delay adds to reliability, all of the other things you describe pretty much happen every time the 1911 cycles.

Frame is not alloy, nor would I have one, the 1911 pins an parts are robust enough that I feel like even if there was a slight change in stress / strain they, in a well made gun can take it.

So thanks again, will be thinking it over as I order and fit parts.

[polyphemus]

Moving the hammer/slide contact point down closer to the hammer pin (center of rotation) greatle accelerates the hammers rearward motion.Probably,it smacks the grip safety,then bounces back.Not sure how good that is

Absolutely,this changes timing and geometry.The current ordnance design is
efficient and it works correctly.In addition the square bottom needs to be radiused can't be a sharp corner,this operation requires special grinder fixtures to be properly done and there are no specific dimensions given.So it becomes
guess work,all Ordnance Department modifications to the original design have
stood the test of time methinks they knew what they were doing.

[James K]

It seems to me that the idea of the hammer delaying the slide would depend on some extended contact of the FP stop with the hammer. But that doesn't happen. The slide hits the hammer and sends it flying back, out of contact with the slide, like a bat hitting a baseball. The hammer then bounces off the grip safety and hits the bottom of the slide at the firing pin tunnel.

The slide hitting the hammer would certainly take some of the energy away from the slide, but I doubt it would be a significant amount, or that changing the FP stop would make much difference (except to the maker's bottom line).

Jim

[polyphemus]

The slide hitting the hammer would certainly take some of the energy away from the slide, but I doubt it would be a significant amount, or that changing the FP stop would make much difference (except to the maker's bottom line).

I agree,energy can not be taken away though and what the radiused FP stop does is distribute the force evenly and use mechanical advantage to push the
hammer down.Also I take a dim view of that extractor clocking concept,unless
the FP stop is way out of tolerance normal allowed rotational play is insignificant and does not affect function.Round coiled springs work fine they really do,squared coiled? they belong with extended guide rods on the shelf
with the dolls.

[RickB]

Does the slide "hit" the hammer, if the slide is in contact with the hammer at ignition? I don't think the baseball bat analogy works, as the slide does not have a running start at the hammer.
Go to an unlatched door, and give it a push near the knob. Open it again, and give it a push near the hinge. Is there a change in how the door reacts to the same amount of force being applied?
Are you increasing the load on the hinge, doing it one way rather than the other?

[HiBC]

Rick,good illustration.

Yes,it does make a difference to the load on the hinge!

If you apply the load quickly.I know you are getting away from impact,but the rapid acceleration is still a factor

In other words,unlock the door,and kick the door at the doorknob.The door will open rapidly,but no spectacular load on the hinges.

Now,move over near the hinges and kick the door.The hinge does take the load,and your foot will hurt.And the door will open more violently.


With a a squared off FP stop,the effort to pull the slide back from hammer down is noticeably higher.There is more resistance to unlocking.

When the gun is fired,that increase in force has nowhere to go but the hammer pin.In the case I was dealing with,a heavier mainspring was installed.Thats a bigger load.Is that a problem?I do not know.

James K,actually,the firing pin stop slides in and covers the rear surface of the slide where the hammer impacts.Once the hammer smacks the inertial firing pin forward,the hammer is only in contact with the stop.The stop is,in effect,the rear surface of the slide.As the lower surface of a typical stop has a generous radius,the point of contact is higher on the hammer,farther from the pin.It slows things down and makes slide racking easier.Installing a square stop lowers the point of contact closer to the hammer pin.The pin is fulcrum,mainspring is load,the hammer is lever.Square stop shortens lever,increases force necessary to overcome load.

[James K]

Again, I doubt the small difference in the leverage exerted on the hammer will make much difference. It would be interesting to see some real physics from a disinterested party. Manual operation is not a very good way to see how an "automatic" mechanism will work in practice.

As to the "head start", it is not needed; the rapid blow of the powder ignition moves the slide so fast, the much lighter hammer is slammed back and down.

Jim

[polyphemus]

The radiused FP stop is an improvement specified by the US Army Ordnance Department,J.M. Browning did not object because he must have agreed that
it was.The Army was looking for the best possible sidearm,if they had determined that the original design was good enough they would not have ordered it changed.J.M.Browning got it right and the Army got it righter.The hammer is not attached in anyway to the slide,upon detonation there is part to part contact
the slide doesn't need to run at the hammer to hit it hard.

[HiBC]

James,I'm just an amateur hobbyist,and you know your stuff.No whizzing contest intended.It was my brother's .460 Rowland,and,in the end,I did as he asked.I just made an observation and expressed concerns.My brother and I do often discuss things at length from a different point of view.

I'm tossing this out there for the purpose of learning.I'm OK with finding out I'm wrong.I learn that way.

I just looked at my 1911.Using my precision calibrated eyeball,I estimate the dim from centerline of hammer pin to the upper tangency on the firing pin stop to be .562.So,that would be the contact point of the slide cocking the hammer,or the length of the lever arm.

Again,using my precision calibrated eyeball and an imaginary firing pin stop with a square edge and a .020 radius,I estimate the lever arm to be .400.

As it is all proportional,the change is .162 divided by .562 makes for approx. 29% change.

Just wild fantasy,suppose the component was designed for a 50% safety margin,or 150% of what is necessary.I'm talking hammer pin.

We have used up 60% of our margin.

I'm not an engineer,either,so,my thinking or math could be wrong.

In the case of this .460,we put in a stouter mainspring,and,after all,it is a 460 Rowland...so now how much margin is left?

I do not know.

Pro-engineer design software can do finite element analysis.I do not have that...but,neither did JMB

[DAVID NANCARROW]

I installed the oversized EGW fps on my Gold Cup, Government Model and Officers Model. I didn't radius the stops on any of them. What I did find is that the square bottom stops slow the cycling of the slide ever so slightly-we are talking milliseconds here, and the perceived recoil is slightly less. It did correct the extractor clocking issues on my O model. The brass isn't scattered all over creation and the distance it throws the empties is less.

There is now a slight wear mark on the bottom of the FPS of all of them. Nothing has broken or cracked, be it pins, frames or anything else. That after a few thousand rounds through each of them.

The only negative I have found is that it takes slightly more effort to rack the slide with the hammer down. That's really not much of an issue for me. Not like I am bulging biceps to chamber a round. That, and I fitted the stops tight enough that I have to use a small punch and tap lightly to remove them from the slide.

[polyphemus]

I would be keen to see a coherent explanation of how this "clocking " thing
affects anything.

[DAVID NANCARROW]

clocking of the extractor affects the ejection of spent rounds to a greater or lesser degree, depending on how loose it is.

[polyphemus]

clocking of the extractor affects the ejection of spent rounds to a greater or lesser degree, depending on how loose it is

I do believe I am conversant with the M1911 spent case ejection process and this does not make any sense to me.Again,the extractor claw holds the case rim
under tension,the rim is round and the claw is flat so there is one point of contact between the two(a tangent point so to speak) basic tolerances allow
for some rotation of the extractor but nowhere near enough to make any difference in tension and that tension is what controls ejection among other functions.When in doubt I posit back into history to see how M1911's were built
and my 1943 Randy has plenty of play in that department.It is in military condition and not a shooter just a teaching aid.

[DAVID NANCARROW]

Polyphemus, I suggest you try out a 1911 with a properly tuned extractor and a flat bottomed FPS vs a GI or sloppy fitted extractor/slide stop side by side and see the difference for yourself. The difference is not gigantic, but it is quite noticeable.

As to requiring special tools and fixtures to radius the flat bottomed FPS, its just not required. All that might be needed is to break the bottom edge with a file, maybe a 1/16th of an inch.

[polyphemus]

As to requiring special tools and fixtures to radius the flat bottomed FPS, its just not required. All that might be needed is to break the bottom edge with a file, maybe a 1/16th of an inch.

Is that it?no radius just a .062" chamfer,I see and the chamfer angle is?
And if if you should file a little harder off one end then what? ship it anyway?

Polyphemus, I suggest you try out a 1911 with a properly tuned extractor and a flat bottomed FPS vs a GI or sloppy fitted extractor/slide stop side by side and see the difference for yourself. The difference is not gigantic, but it is quite noticeable.

I dare say that all my M1911's have properly adjusted extractors.
And since I hold that flat bottom FP stops are a waste,won't be replacing any.
Also don't much care for pistols that have somebody's full name on them
military sidearms are not swiss watches.

[DAVID NANCARROW]

you win. my mistake

[polyphemus]

you win. my mistake

Have a laugh man.Too many years in the machine shop.Everything had dimensions and a print.