Springing down a 1911 - which mods work?

[Tom H.]

Now that my 1911 project has actually gotten somewhere, I wanted to shoot 45 super without the 28# recoil spring.  I was told that I can raise my mainspring up to 25# and add a firing pin stop with a minimal bevel on the bottom.  This should keep th e gun locked up longer and let me lower the recoil spring.
Thats all I know.
 
Anyone have any other info, ideas, or experts that might be able to explain any of this?
I spoke to a fellow at Brownells who was very knowledgable but I didn't get the explanation that I was looking for.
 
Thanks
 
Tom

[gray wolf]

The 45 auto was made at first with a square bottom F P S or as you say a very slight bevel. Men were to carry with an unloaded chamber on horse back.
It was complained that it was to hard to rack the slide.
( flat bottom F P S = more resistance on the hammer face
= a little harder to draw back the slide. )
  The FPS was given a larger bevel to facilitate a little easier drawing back of the slide.
and is what most 1911 pistols have adopted today.
  Going back to the square bottom stops allows for a small amount of increased dwell time, the square bottom F P S offers a little more resistance to the hammers rear word movement.  The main benefit most shooters seem to find is more of a straight back recoil and less flip to the side. Pistol recoils straight up and straight down allowing for a faster follow up shot.  Some folks do not realize this.
I do and so do many others.
  As a side benefit you may be able to up your hammer spring a little at the cost of increased trigger pull.
I doubt you will be able to lower your recoil spring to much, recoil spring has to do a certain job to allow the pistol to function properly.
  You may be able to try a little lighter.
Lighter load = lighter spring, heavy load most times needs the spring that will allow the slide to function as it should.
  Why are you wanting to change the recoil spring ?

[Tom H.]

Thanks for the reply gray wolf.  That was great info.  After knowing what to look for I surfed the net for a while and saw exactly what you were talking about.
Tonight after work I installed that flat FPS and I broke the edge slightly to make it similar to the original browning design that I found online.  I upped the mainspring to the 25, and I dropped the recoil spring to 26.  Results were promising.
The pistol ran well although the slide closed on one magazine.  It hadn't done that before so I may actually be able to drop the spring a bit further.
I am concerned that a very heavy recoil spring, although it does stop frame battering from the slide coming back, will beat up on the slide release lever and the barrel feet on the return trip.  I may spring up my mags as well to create a bit more friction and ease that up.
Any other thoughts would be appreciated.
 
Tom

[gray wolf]

  Sounds like your on the right track, good on you for looking into the subject a little more on your own.
Now if you have not done it yet,
Take a sharpie marker and coat the face of the hammer, let it dry and rack the slide a few times ( unloaded pistol )  what we are looking for is a nice even rub mark on the hammer face.  This tells us that the interface of the F P S and the hammer face is even across both surfaces and will not induce side to side stress on the hammer,
This condition can induce premature  wear on the hammer pin and possibly egg out the frame hole. Get it the best you can.  A nice even strike in the middle of the hammer face is better than a heavy one on just one side.
  I think you meant to say the slide closed on an empty Mag.
>>>Week or worn slide stop<<<
>>bullet nose to long and it hits the little nub of the slide stop inside the frame.<<
>>Mag follower not up in the correct position / week mag spring <<
There are a few more reasons also
  Remember when you change one thing, you increase the chance to have other things change on there own. ( I hate when that happens )
  It's why it's best to change one thing at a time.  Makes it a lot easier to track down a problem.
  The recoil weight of the spring should match the power of your load in a properly functioning pistol.  Yes you are correct in that a heavy spring will batter the frame in it's forward movement.  You want the pistol to eject the case and load a new one, while maintaining the proper timing, it's that simple.
  Many folks over spring  instead of fixing the problems.
Look at the back of the case after firing, how does the primer look ?
is there a drag mark going up? or a nice round mark ?
elongated primer strike is an indication of the pistol being out of time.
  The slide opens before the firing pin has retracted back into the slide.
Over springing can cause this,
( well my pistol never misses a beet with a nice heavy recoil spring  )
Sure it does, your slamming it into submission.
 ( well I want it to cycle faster )
how the hell fast do you need to have it go in and out of battery anyway.
Are you able to squeeze the trigger in mid cycle ?
 NOT YOU--just some examples.
Pick the load you want to use and match the recoil spring to the load.
 The first thing I do is run a pistol with a load the gun was made to shoot or should shoot well. If it does not, I fix the problem.  Then if I alter the pistol and have a malfunction I am fairly sure it was induced by me and the change I made to the mechanics of the firearm.
  I would purchase a multi pack of different recoil springs in different weights.
Find one that allows the pistol to function correctly, then you can drop down a little at a time until you start to have problems, Then go up again to proper working.
  If it works well why would you want a heavier spring anyway.
Your going to be happy with your work, your approach is sound and your willing to try different things. 
If it gets out of hand go back to a stock set up and replace one thing at a time and work out each issue as it comes up.
  Sorry for being mouthy and long winded.
 
 

[Tom H.]

Glad you mentioned the issue regarding the firing pin. Now with things changed, the pin has a major upward drag. Strangely enough it didn't have those issues withthe 28# and the standard  hammer spring.   I will probably put in an increased power firing pin spring to see if that works.  It was recommended for the super anyway.
Thanks for the heads up about the FPS, common sense but didn't come to mind.
That is the next step.
 
Tom
 

[gray wolf]

The F B F P S should have slowed down the slide just by the nature of the resistance to the hammer.
  The mod to the FPS is to retard the slide, the lighter recoil spring increases slide speed, heavy hammer spring slows down the rear travel speed.
  I am not sure I was privy to your original intent.

[Tom H.]

Range report.  I pushed it back up to the 28# and there is still the slightest smear on the primer but better than the 26.  All very surprising because I didn't get that with the heavy spring and the standard 5" barrel before the changes that were meant to stop it with the longsilde
.
Agreed, any experiment has one variable and I decided to change 5.
 
I guess that if it was a research paper they would give me poop during peer review.
 
 
I found a pic of the original 1911 design here
http://www.firearmstalk.com/forums/f57/firing-pin-stop-59855/ and mine looks more like that than the one that the poster tooled up. I may pick up another to see if a smaller radius solves the problem.  Probably sould have tried that first but the very small transition looked too short.
 
All of that said, did a bit of research and I found a more useful load for hunting. Power pistol and the 240 xtp.
Although I haven't clocked it yet, it should be moving at around 1000.  I have found data around the net from more than one poster on a number of sites (and ammo makers) that say I should be able to work up to at least 1100 without any ill effects.
 
The accuracy was impressive and currently no primer smear.
 
Thanks
 
Tom