Project #4 Flat Bottom Firing Pin Stops

[Bud White]

Well its been a while coming due to time work etc a small project but one that i think will be interesting

Now if you have read the 1911 forums you have probley heard of the flat bottom firing pin stop from EGW

Depending on who ya read this thing does nothing to best thing since sliced bread ..

One thing that is a good thing, is you have to fit it its oversized and i mean oversized ..Also if you do this only do one a day your fingers will thanks you trust me

Also ya do a Les Baer use the Series 80 one it makes fitting a lot easier..

Ok So what does the firing pin stop do? Well its name gives part of it away but it also does 2 other things it cock's the hammer and also alters timing ..

The flatter the stop the slower the slide is supposed to run as there is less leverage for it to cock the hammer..Also in running slower the timing is slowed down...

In theory this will slow down muzzle whip..

The Guns i chose are a Springfield Loaded one of the 1911's I've had the longest and been shot a ton ..

In the pic its the left stop sorry i tried 20 different shots of a close up of it and it never came out .. But as you see it has a big radius



Thats from a 5" gun

now the Middle is from my Les Baer Concept VIII it is a 4 1/4 inch barrel or commander size..

I do notice and have commented to OD and Qkshooter that the radius is a lot smaller than the springer or colts and recoil feels different but not reduced..



Then the last is the Flat bottom stop as you see..



A Small radius is recommended but you do not have to have it if your gun will run on it flat ..

So being the show me guy i am im going totally flat

The other test guns are a Colt Commander 4 1/4 to compare to the baer yeah i know the baer is tighter but figured i was gonna put the stop in one shot a lot ..

The Springer is going up against the Les Baer Concept III 5" in the beginning i wont shoot groups for fell and am hoping i can get one of the shooters i shot with a lot to help me out for feel also he has shot my baer's a decent amount so know the feel..

everything is gonna be shot with 230 Ball

After a shooting for feel i might change the pin stop out for the factory to see if the groups improve at speed or a quicker recovery with the Flat bottom ..

So hopefully the test will be friday

I would thinking of putting one in the Kimber but the 4" Bull Barrel to 4 1/4 Barrel wasn't a Apple to Apple Comparison

..


Anyone have any other ideals? Sorry don't have a 3" to try i would be uber interested to try it out in a 3"

[DefensiveCarry.com]

[OD*]

Nice write-up Bud.

I have done the original radius (.078") FPS on two Colt pistols, and my 1913 has the small radius FPS as original equipment (radius changed to 7/32" in January 1918). To be honest, I didn't experience much change (tested two 1991 Colt's, one with the factory FPS and the other with the EGW, and both with new 16lbs. recoil springs). I plan on ordering a couple more, one for the OACP to see if it would make any difference in it and because I like a tight FPS to alleviate any clocking of the extractor.

[Bud White]

I left out the Prevent Clocking of the extractor didn't I ?

I think where it will really shine but thats later tests are in a 10mm or 38 super with full power loads.

Also forgot to add the Racking of the slide hammer down is a lot stiffer.

[OD*]

Yes sir, it may make a real difference in the 10s and Supers, I would be very interested in your thoughts when you get around to doing them. I "think" the shallow radius FPS might make a little difference in my LW Officers.

[Bud White]

maybe i should have done one in my 5" lightweight

[OD*]

That might be a good test also, Bud.

[Bud White]

Wonder if it would swap out from the 5" to it ill check it out later

[OD*]

Probably would work, no deference other than fit.

[Bud White]

I bet slides are close enough im sure as heck not filing another tonight

[OD*]

Tedious work, isn't it?

[QKShooter]

I would be real curious to know if there is actually any noticeable delay in the slide/barrel unlocking - to any degree that you feel any real recoil reduction or reduced muzzle whip.
That will be an interesting experiment and you're got me really wondering what your results will be.

I would additionally say that one would need at least a full weight mainspring/hammer spring installed.

I know that when folks install too light of a hammer/main spring (thinking that they are going to reduce the felt pull weight of the trigger) that causes the pistol to unlock too early.
When the 1911 unlocks prematurely it causes extraction problems because the extractor yanking the fired cartridge case out of the barrel chamber is integrally tied in with the rearward slide travel.
When the slide/barrel unlock super early the extraction process starts while the cartridge case is still expanded/locked against the barrel chamber walls.

Also Interesting is that the Firing Pin Stop that you're showing on the left has those two "tell-tale" circles (showing on the part) which is indicative of it being a cast rather than a "machined from bar-stock" part.

While BOTH a cast and a milled/machined slide stop will serve exactly the same function as long as they remain intact...the difference is...that should the ever part "fail" (through repeated hammer blows) the cast part will usually shatter causing an immediate pistol stoppage - while the milled/machined part will just develop a hairline fracture that travels from the edge of the firing pin hole to the closest square corner and the pistol still remains FUNCTIONAL and usable even with a cracked FP Stop.
So the cast part creates a catastrophic failure while a cracked milled/machined FP Stop just creates an issue that needs to be eventually addressed.
Just FYI.

[Bud White]

all good points QK the Mainspring is recommended at 23# with this stop and 16# recoil spring

Also i was thinking the pin stop on the left was mim not cast but your probley right

[OD*]

I believe your correct Bud, cast normally has a flange line, I would say that FPS is MIM.
What pistol is it out of?

[OD*]

all good points QK the Mainspring is recommended at 23# with this stop and 16# recoil spring

Colts made prior to 1918, used 14-15lbs springs, you can get away with using a lighter recoil spring with the shallow radius FPS. I think that is the reason a lot of folks are claiming reduction in felt recoil, is because they have went with the lighter springs.

[Bud White]

Could very well be ..

im sticking with the 16# in the 5" plus its not a true comparison if i change everything

i would rather run it with the heavier spring than a lighter unless they are softball loads