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SR1911 Firing Pin Spring Weirdness

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2K views 14 replies 9 participants last post by  ManxTom 
#1 · (Edited)
I picked up a used SR1911 Target in 10mm a couple weekends ago. I know the previous owner did some stuff to it because the trigger measured just over 2 lbs…too light for me! I replaced the recoil, hammer and safety plunger springs with factory springs. I added tension back to all three sear spring leafs and got the trigger into the 4-4.25 lb range. I did not change the firing pin spring because it hadn’t arrived yet.

Off to the range I went. Everything fired but some very shallow primer indentations. See picture below of two 10mm spent casings next to a 9mm casing shot from my DW TCP. I’m kinda surprised everything went bang.

Performed the pencil test and it seemed to pass but it wasn’t great. My firing pin springs came in today and I find that the previous owner installed a second, smaller spring (maybe a magazine spring???) under the firing pin spring to serve as some sort of homemade dual firing pin spring. See picture. Took both springs off and installed a Wolff extra power spring. Performed another pencil test and it was noticeably more forceful.

Now for the question… Is this “dual spring” some sort of trick / method to set the gun up for competition or something else? Any reason for this to be done?
 

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#3 ·
Or tried to eliminate firing pin strike ‘tails’ from primers using high end loads.
 
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#6 ·
Good find.
I would test it again with the correct-esque looking FP spring and no other changes.

Not the same thing at all but I just picked up a P-08. I ordered a Wolff spring set before I even ordered the gun. When the gun arrived I found a combination of 100 year old and/or Bubba'd springs. I replaced everything before I took the first shot. I'm getting close but still troubleshooting.

You don't have the age to worry about but the Bubba factor still exists.
 
#7 ·
Good find.
I would test it again with the correct-esque looking FP spring and no other changes.
That is the plan. I already had addressed the other springs so I should be pretty much back to stock configuration now. If I still don’t get good strikes then I’ll try a 25 lb hammer spring from Wolff.

I’m fairly new to 1911’s and have learned a lot from this site and others but know Bubba well from some experiences buying used revolvers. Makes for good learning opportunities though!
 
#9 ·
A full-sized 1911 should never exhibit primer drag. If it does then something is wrong and the slide is unlocking too fast. I've seen stranger things on 1911s than an extra spring like that, but you were wise to remove it and put a stock setup back in.
 
#12 ·
The upper power 10mm may do it. The 10mm I built locks solid, has the square bottom firing pin stop with a very small radius and the top bevel, 26 pound mainspring and extra power firing pin spring. It exhibits only the slightest drag marks. Further measure to eliminate the drag produces no further reduction in drag impressions.
 
#14 ·
Quick update. I was able to squeeze in a quick range session today before getting to work on my deer blinds. The primer strikes are much better and consistent. Sig, S&B, and Federal all looked great. Hornady still looked a little light but went bang every time. I’ll keep an eye on it but I think it’s good to go now.

Side note: This thing ejects empty cases with a vengeance!
 
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