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Old January 17, 2013, 03:06 PM   #1
whiplash
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Ok 1911 guru's got a parts question/problem

Actually 2 questions. Does the firing pin stop have a loose/snug/or very tight fit when inserting into the slide during assembly? On my son's Taurus, (ya I know dont waste your breath, couldnt see giving him a higher end 1911 for the first one)....Anyway, the firing pin stop has dimples on both sides (front and rear). Its like they were left over from manufacturing??? The fit is way to tight in my opinion, but maybe thats the way its supposed to be??? It took small punch and hammer for removal and installing. I did take some emery cloth to smooth down the fit and that seemed to fit. Question two... due to this tight fit, would it cause any hang ups with the firing pin plunger preventing the firing pin from traveling the full length travel during firing? I recently had about 2-3 rounds of a mag not fire. The primer had very light primer strikes/marks. When I reloaded the sames rounds, or recock and fire, the rounds fired fine. Reloads haver never failed in other guns (45acp), and are measured correctly on COL, crimp, not long or short when checked in barrel chamber itself, etc. I just wonder if any of that rough fit would keep the firing pin from traveling the full length. Are other firing pin stops loose or snug??? Any thoughts?
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Old January 17, 2013, 06:44 PM   #2
polyphemus
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Guru 1911ananda says...
The firing pin stop should fit snug but not so tight that you need tools to remove it,once it is in place it does not interfere with firing pin travel regardless
of fit,if you are having trouble inserting or removing chances are it is out of
specs,replace it if you are not comfortable fine grinding parts.
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Old January 17, 2013, 06:50 PM   #3
HiBC
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I have seen a firing pin increase in diameter,from mushrooming due to dry firing,to the point it became tight in the firing pin stop.Temp fix,spin it in a drill press and dress it with a file or stone,but then order a good firing pin.
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Old January 17, 2013, 07:23 PM   #4
RickB
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You should be able to easily determine if the problem is the firing pin binding in the firing pin stop, or perhaps, an issue with the Series 80 system. Pull the trigger all the way to the rear and hold it there, then use a punch to depress the firing pin. If the pin drags at all, then you need to determine what's dragging, and where.
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Old January 17, 2013, 07:44 PM   #5
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As posted about, the firing pin stop should fit tight, but should not require Herculean effort or power tools to remove. I like a very slight press fit, just enough to prevent the extractor from rotating in its bore (known as "clocking"). But I've seen 1911 in which the stop was so loose that, if inserted with no firing pin, would just fall out ... and the pistols functioned.

A Taurus will also have a Series 80 style firing pin safety, and if that's not properly set up the safety can interfere with the firing pin, resulting in light strikes.
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Old January 17, 2013, 07:53 PM   #6
polyphemus
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Not to be overly minute here,but in order to depress the trigger while holding the hammer you have to get a good grip on the pistol,then you want
the man to push a punch into the firing pin and test the action thereof.
Do yo do this yourself?
Field strip the pistol and visually inspect all the moving parts for damage here
is when the firing pin travel can be checked for proper function.
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Old January 17, 2013, 10:08 PM   #7
Aguila Blanca
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Quote:
Originally Posted by polyphemus
Field strip the pistol and visually inspect all the moving parts for damage here
is when the firing pin travel can be checked for proper function.
What RickB is suggesting is a way to test for whether or not the lever is fully lifting the firing pin safety plunger out of the path of the firing pin. To do that, the slide has to be on the frame and in battery.

One way around the need for a third hand would be to simply drop the mainspring housing down far enough to take spring pressure off the hammer, leaving the slide in place on the pistol.
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Old January 17, 2013, 10:45 PM   #8
polyphemus
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Here's the thing:during a different discussion regarding the series 80 block
a well regarded authority on the 1911 suggested that visually inspecting
the plunger for damage was the way to know whether all parts involved were
functioning correctly in other words if the plunger shows no sign of damage
it is not interfering with the firing pin during normal operation.
This is a sensible way to check the mechanism without going through contorsions or dropping the main spring housing,the fact that reloaded ammo
was used introduced yet another factor to be considered but those "dimples"
certainly don't belong in the firing pin stop.
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Old January 18, 2013, 12:36 AM   #9
RickB
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Performing the test I described requires no disassembly, and no contortions. I can hold the trigger and hammer with one hand, and depress the firing pin with the other. The test takes ten seconds, beginning to end.
Where are the dimples on the FPS? Sometimes, people will apply a punch near the edges, kicking-up burrs that tighten the fit in the slide. It's not something I'd expent to see on an unmodified, stock gun.
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Old January 18, 2013, 05:48 AM   #10
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Leverage

Another way to check it is to take the pretravel out of the trigger and measure the distance from the top of the lever to the top of the frame. .060 inch is what you want. Then, pull the trigger full rearward and measure again. .090-.100 inch is good.
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Old January 18, 2013, 12:19 PM   #11
whiplash
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Thanks for the replies. I did use RickB's tip and had interference with the firing pin travel, However, I was doing this with the barrel pointed down on the table. Once I put the gun parallel to the ground it had clear travel. I did remember that the last disassembly I noticed the firing pin plunger spring cocked a little bit, possibly from my last install. And yes I wouldn't expect the firing pin stop to have dimples and the opposite bumps. It's like someone used a flat ended punch for one side and the other side has what would be the opposite with round bumps. When I get a chance I will take a pic that would help explain. Unless someone with a Taurus beats me to it.
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Old January 18, 2013, 02:49 PM   #12
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re:

Quote:
I did use RickB's tip and had interference with the firing pin travel, However, I was doing this with the barrel pointed down on the table. Once I put the gun parallel to the ground it had clear travel.
Been tryin' to wrap my head around why that would make a difference. If the system is timed and functioning correctly, it should work regardless of the orientation of the muzzle.
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Old January 18, 2013, 06:27 PM   #13
whiplash
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Ya that through me as we'll. after I took a pic of the firing pin stop and reassembled, I checked it barrel pointed down and it worked fine. Wonder if it had anything to do with a cocked/canted firing pin plunger???
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Old January 18, 2013, 07:41 PM   #14
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re:

Quote:
Wonder if it had anything to do with a cocked/canted firing pin plunger???
Nah. Not enough wiggle room between the plunger and the hole to do that, especially with it bein' spring loaded and all.
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Old January 18, 2013, 08:11 PM   #15
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Back a bit to the firing pin stop. Many folks have heard of the firing pin stop dropping down and hanging up the gun, hence the concern to make it a tight fit. There is no harm in doing this, by peening it but some understanding as to how the firing pin stop could drop down might help.

When the hammer hits the firing pin, the firing pin moves forward far enough to strike the primer. But it cannot normally move far enough to clear the firing pin stop and the slide movement to the rear cocks the hammer in the normal manner, just like in the pictures.

But, with hot ammunition, and some gun characteristics like an extended ejector, the fired case is kicked away from the breech face before the firing pin loses inertia, so it continues to move forward. That pulls the rear of the firing pin out of the firing pin stop.

Now in the pictures, it looks like the slide moves gently back and pushes the hammer so the hammer stays in contact with the FP stop and it can't move down. But that is not what happens with hot loads. The slide moves back so fast and hard that it strikes the hammer, driving it back and down out of contact with the slide. So, with everything just right (or wrong) the firing pin is clear of the slide stop and so is the hammer.

Meantime, the gun has begun to recoil upward. The firing pin stop, having nothing to hold it in place, tries to remain where it is as the gun moves upward. The firing pin stop thus moves down (in relation to the gun and slide) and ends up between the hammer and the frame, jamming the gun.

It is a neat case of timing, and won't happen except with hot loads. It won't happen with standard GI loads. But it happens often enough that "gurus" advise shooters to stake, peen or otherwise make sure that the firing pin stop won't move down and hang up the gun.

Jim
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Old January 19, 2013, 04:30 AM   #16
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Jim's assessment is pretty much spot on. I've seen it happen with GI ball and equivalent handloads, and the common thread almost always includes a weak or short firing pin spring.

I've staked the edges of firing pin stops as an expedient measure, but prefer a fitted stop. No need to make it so tight that it requires a punch and hammer to move it, though. Just enough to keep it from falling from gravity is all that's needed, and using a punch or the tip of the hammer strut to pull it down is acceptable.

The side benefit of using a fitted stop is that it makes for more consistent ejection by keeping the extractor aligned.
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Old January 19, 2013, 02:50 PM   #17
whiplash
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Those are some interesting notes. I won't worry about the remaining stake marks and dimples as the firing pin stop is now a snug fit. Not as tight as it was. My reloads are not hot, just in the middle mild. I am going to shoot it tomorrow with the same loads and well see what happens. And hopefully get that pic downloaded. If I remember how??? Does downloading pics still take photobucket type site??? It's been a while
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Old January 20, 2013, 04:15 PM   #18
polyphemus
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firing pin stop

Please indulge my skepticism,the firing pin strikes the primer and it's immediately
pushed back and cannot lose inertia since the slide is going back as well.In addition to that the primer depression is about +-1/32 so it doesn't seem possible that the firing pin can be unsecured to the slide long enough to cause that failure.A mechanical defect eg. broken or tampered with spring would of course but even a +P is too far fetched.I go to the basics when in doubt and
my Rand's firing pin stop is loose and I suspect that all those pistols soldiers
carried to war had the same fit,so the way I see it this is an issue that sells
a $20 tool to free a part that is not designed to be pried lose.
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Old January 20, 2013, 04:17 PM   #19
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I had an Auto Ordnance that would drop down and hang everything up. I replaced the spring and the stop and cured it.
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Old January 20, 2013, 04:23 PM   #20
polyphemus
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So glad it was a faulty spring and not Browning's fault.
Did you buy the stop with a set screw? I see that one for sale too.
These solutions looking for an issue amuse me.
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Old January 20, 2013, 06:05 PM   #21
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re:

Hawg, it's almost always a weak spring.

Had a Colt Enhanced Combat Commander XSE that belonged to a neighbor that did it twice on its maiden voyage. It would drop and hang on the hammer.

Series 80 firing pin springs are quite a bit shorter than standard springs. I installed a standard spring and the problem disappeared.

Quote:
the way I see it this is an issue that sells
a $20 tool to free a part that is not designed to be pried lose.
No need to fit one so tight that it has to be pried out. As long as it doesn't fall out under its own weight, it's good to go...completely solving any problem once and for all...and a fitted stop offers the added advantage of keeping he extractor nailed down. Can't clock and can't shift back and forth. Win-Win.

No need to buy a 20-dollar tool, even if it does need prying. The original hammer strut works just fine for that.

Then, of course...with an EGW stop...there's the option of cutting a small radius on the bottom corner to add a little delay to the slide and bleed off a bit of it's rearward momentum...as per the original design.

In the 80s, when the old 5/64th radius stops got scarce, I made my own. When George Smith started offering them with dead square bottoms a decade later, I thought I'd won the lottery and started experimenting with an even smaller radius...down to .050 at one point, and eventually settled on about a 16th. Some people just leave'em square and go.
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Old January 20, 2013, 06:13 PM   #22
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Stop Radius

Here ya go, polyphemus. The one on the far left is the standard since January 1918. The one in the center is one of mine, cut to roughly .070 radius...just slightly smaller than Browning's.

I found the one on the far right in a late production pre-Series 80 Combat Commander. It's got a slightly smaller radius than the now-standard 7/32nds.
Not sure if that was a fluke, or if Colt was experimenting.

Study these and see if it comes to ya how that radius would make a difference in the slide's delay and momentum. Don't let that single eye mislead ya, now.


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Old January 21, 2013, 11:45 AM   #23
polyphemus
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firing pin stop

Thank you for the pic.As I understand the prototypes had flat bottom stops and
the militari specified the change to a radiused leading edge.I have to say that
they were right on this one,the prints available to me call for an offset .220" R
leaving a 1/32 +/- flat I could not say how a different radius would make a difference .220" is probably tried and true.How the rounded edge affects momentum is logical,more slide leverage thru longer contact,clear mechanical
advantage and smoother action compressing the main spring.I can;t make out
the edges very well but I get the idea don't need the loupe for this one.
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Old January 21, 2013, 02:30 PM   #24
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re:

Quote:
As I understand the prototypes had flat bottom stops and
the militari specified the change to a radiused leading edge.
The Army Ordnance department made the change after complaints from the mounted troops over the slide being difficult to hand-cycle with the hammer down, and for no other reason.

Quote:
I have to say that they were right on this one
I'll have to disagree. Again, I was so impressed with the effect of the original 5/64ths radius stop that...when the originals became scarce...I went to the trouble of making my own.

Quote:
How the rounded edge affects momentum is logical,more slide leverage thru longer contact,clear mechanical advantage and smoother action compressing the main
The smaller radius affects delay and momentum purely through reducing the mechanical advantage in cocking the hammer and overcoming the mainspring. A matter of simple leverage.

And there isn't a smooth action in compressing the mainspring, regardless of the firing pin stop radius. Its effect is brief, but telling.

The hammer doesn't remain in contact with the slide, but is rather slammed backward...bounces off the grip safety tang...and falls back to the slide, striking it roughly at the junction of the stop and the center rail, assuming that the mainspring is to spec and in good shape.

The photo below illustrates the "Strike Zones" of the hammer on the grip safety and the stop/rail junction. The damage is most often seen on soft pre-1946 production slides, but it's occasionally seen on newer, hardened slides with enough mileage. Another plus with an oversized fitted stop is that you can leave it just a few thousandths below flush with the center rail, and avoid the peening on the rail. The stop catches all the hell. In the photo, the peening was done before the oversized/square stop was installed.



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Old January 21, 2013, 02:43 PM   #25
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Peening

Here's the same slide from another angle.

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