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Old 03-09-2012, 10:32 PM   #1
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Default Firing pin stop:

Hi everyone, I've never posted but have been around a couple of yrs.
Alot of interesting stuff on this forum, I've learned alot just by being a
lurker.
I am a 1911 fan and like doing a limited amount of smithing on my guns.
I'm going to fit a firing pin stop with the squared bottom corner because I want to see what effect it will have on shootability. I've read about how it
retards the slides movement and that it makes the pistol feel somewhat
different durring recoil. I'm curious to find out if this will mean a change
in recoil spring #'s needed or not.
I guess I'm just curious period.
I'm waiting for my parts from Wilson, and will post my conclusions after
I finish this mod.
Any opinions out there are welcome.........
Thanks

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Old 03-09-2012, 10:42 PM   #2
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i dont see how a square stop would change anything in that regard.

if i remember right the reason for the rounded bottom was to decrease the stops from breaking as often.

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Old 03-10-2012, 12:08 AM   #3
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Quote:
Originally Posted by JonM View Post
i dont see how a square stop would change anything in that regard.

if i remember right the reason for the rounded bottom was to decrease the stops from breaking as often.
Exactly- heard something about that some time back but its completely pointless IMHO
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Old 03-10-2012, 08:26 AM   #4
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Two things to consider with the square stop:
1. Lock time is supposedly faster (not that most of us will notice)
2. Accelerated wear on the hammer (a square sliding on the hammer flat area will develop a groove in the hammer area if the slide is hard enough)

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Old 03-10-2012, 07:48 PM   #5
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I can understand accelerated wear on the hammer...... but how would a
squared firing pin stop have anything to do with how fast the hammer
falls ? ( lock time )
Thanks

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Old 03-10-2012, 08:05 PM   #6
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Maybe lock time not was the best term.
The hammer is reset faster to the locking position. But the downside to the square stop is that the parts are working harder together. With a rounded stop, there is less resistance to get the hammer in the cocked position.

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Old 03-11-2012, 04:55 AM   #7
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The fps your refer to is not square, it is just a smaller radius than what comes on most 1911's. It is how the pistol was designed originally by JMB. It does not cause any issues with the hammer, and works fine with the 16# recoil spring that is in most 1911's. The reason the fsp was changed is because the army decided the slide was to hard to pull back and needed something that was more user friendly I guess you could say. It will reduce felt recoil somewhat an is worth adding to your 1911 as long as the increase in force needed to pull the slide will not be an issue.

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Old 03-11-2012, 05:59 AM   #8
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Thanks EDM1911 for your response, I knew that from a simple mechanical
standpoint changing to a stop like that would have to have an effect on
the recoiling slide. I'm going to fit one of these with a small radius to my
carry gun and see how it works for me.

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Old 03-11-2012, 07:36 AM   #9
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Actually Browning designed the 1911 with a near-square bottom firing pin stop.

The modified design found in today's 1911 FPS's is a little known change Browning made due to the complaints (by horse mounted soldiers that were carrying hammer down on an empty chamber) that it was too hard to rack a round to battery.

fps2.jpg

I use the EGW Oversized, Square Bottom Firing Pin Stop. EGW - Firing Pin Stop



They definatly produce the effect of delaying slide opening. (barrel unlocking) I had a problem with my CCG 460 Rowland kit that exhibited evidence of firing pin drag in its contact with the primer. The firing pin imprint looked like a stretched out comma. It comes from the barrel dropping while the firing pin is still in contact with the primer. Instaling the EGW square bottomed FPS eliminated the smear. (I was already using the heavy duty firing pin spring that has the effect of rapidly returning the pin.)



From Guncrafters Industries;

A square bottomed firing pin stop serves to slow down the opening time and reduce the slide speed when firing powerful loads in a 1911. This is due to the contact point between the hammer and firing pin stop being lowered. The principal of leverage applies and it now takes more force for the slide to overcome the hammer spring tension, thus the slide speed is reduced. This can also be a desirable feature in competition pistols where it allows the shooter to run a lighter weight recoil spring for lesser perceived recoil. Our firing pin stops are made to max. [sic] factory dimensions to prevent excessive extractor movement, an important feature for increased reliability and proper function, and the corners are radiused to eliminate stress fractures. Machined from 4340 Chrome-Moly steel and properly heat treated, this is one tough part.
The most effictive use of the FPS is to radius the sharp corner that contacts the hammer. This radius is minor but removes the 90º edge and replaces it with a 16th inch radius on 5-inch Government models, a .075 on Commanders with 18-pound recoil springs or a 1/16th on Commanders with 16-pound recoil springs and 1/10th to 1/8th inch radius on the Officer's Model.







An important part of this system is the use of the standard 23 pound mainspring.

Just another example of the brilliance of John Moses Browning!
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Old 03-15-2012, 12:18 AM   #10
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No comments?

This is a easy fix/improvement.

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