Flat Bottom Firing Pin Stop - Witness Match

[DougM]

I've struck out trying to buy a FBFPS for my Match so I got a spare FPS from EAA to play with.  I welded up the taper on the bottom and then filed it down to the same shape as a normal FPS but with a flat bottom and a very slight roundover where it hits the hammer.  I fit it to the slide and went to the range excited to see the difference.  Nothing was different.  After examining the geometry closely, I realized I made a fundamental error in my assumptions.  The bottom of the FPS hits the hammer about halfway up and not near the bottom like a normal 1911 does.  So there is almost no difference in the leverage on the hammer between a normal FPS and a flat bottom FPS.   So all this was a waste of time.  Bummer!

So the only thing I could think of to help control the 10mm brass ejection was to install a 22lb hammer spring.  That, together with the 20 lb recoil spring, provided some help but the brass still tends to leave town when it is ejected.  Guess chasing brass is the cost of shooting 10mm.  So be it.

[Astocks2622]

Have you shaved down the ejector on your match? I reduced the length of the ejector on my 10mm Stock 1 by almost half, and with mid range loads brass now ejects about 8-10 feet, instead of 18-20...

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[johnbu]

^ what he said.

You can CAREFULLY file the ejector shorter and play with the angle to affect the brass flip direction and distance.

 

I highlighted carefully as too short can  be an issue and the sear cage is spendy. Just file or grind little by little and test. 

[Astocks2622]

Yeah, there are a few threads about it that give you estimates on how short to go. I can measure mine if you want, then go a bit longer and work down.

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[DougM]

Sounds like filing down the ejector is the way to go.  Astocks2622, if you can measure yours, I'd appreciate the info. 

Also, mine is currently square cut and tends to eject brass more vertical than I would expect.  Would cutting an angle on the ejector help lower the ejection direction?   I shoot outdoors but under cover (roof is about 10') and brass frequently bounces off the rafters and goes in all sorts of directions.  

[Astocks2622]

I should be and to do that this evening. The gun is currently on my hip while my wife and I are waiting for deer to show up... I put a slight undercut on my ejector to flatten the rainbow, not sure it did anything.

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[Astocks2622]

Looks like I stored at .375" measured from the rear of the ejector to the foremost point.



Second photo is just to show how/where I'm measuring from. Forgot that I ended up going with a slight cant to the rear for the ejector instead of an undercut. That might be part of why it only goes 8-10' to the side, might be going up quite a bit instead. I rarely shoot this with anything over my head, and if I do it's at an indoor range where the brass hits the lane divider and bounces all over around me...

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[DougM]

That info is great!  I'll definitely work on my ejector and will probably start cutting it only halfway to your 0.375" - and I'll add an angle to it as well.  Maybe that will lower the ejection angle some.  I likely won't get to try it until the end of next week (range is about 45 minutes away) but I'm anxious to see how it improves.  I wouldn't be at all surprised if I eventually get to the same 0.375 you got to.

Thanks again for that info.  Much appreciated.  I'll let you know how it goes.

[DougM]

Well, I shaved down my ejector down to 0.395" from the original 0.541" (measured the same way as Astocks showed above.   I also added a slight taper, again like Astocks ejector, to see what that does.  It definitely helped reduce the distance the brass ejects but it still goes quite a bit more vertical than I'd like.  If I square off the end rather than have it tapered, think that would help throw the brass more horizontally?  I plan on shortening the ejector some more so that would be a good time to make the change.  Thoughts?

[MemphisMechanic]

Yes, the higher up on the brass the ejector hits, the flatter the brass will fly. Hitting it lower (like his undercut) will cause more of a rainbow arc.

Hit it down low, and it will flip upward...

[Astocks2622]

What he said.

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[DougM]

Thanks for the replies.  Since I should probably shorten the ejector a little more, I'll just square it off and remove the taper.  That will probably account for about 20 thou and get me down close to Astocks level.  Hopefully, this will make it a little easier to find that brass. 

[johnbu]

Just be aware if you switch to "minor" pf you could have ejection failures unless you match the recoil spring to allow full cycling.

[DougM]

I squared off the ejector and ended up with one 0.355" long.  At the range yesterday, it still threw brass between 25' and 30' but that is a lot better than the 60'+ that I was getting.  It still properly cycles 40S&W (changed the barrel, of course) so I'm content to let it as is.

To your point, John, I have lighter recoil springs available should I need to go down in PF so I should be good on that score.  I will have to be conscious of that so if and when I go to minor loads, I'll need to drop the recoil spring weight back to the original 12 lbs.  I've successfully cycled loads down to 135 PF with this spring (but with the lighter hammer spring) so I should be close.  

So to net this out, I've got a 20 lb recoil spring, a 22 lb hammer spring, a shortened ejector, and a home-made flat bottom FPS.  Since the springs are the strongest I can get, I guess this will have to be my final solution.  Thanks to all who have contributed their thoughts.  Much appreciated.