Auto Ordnance 1911 thumb safety fails

[Equanimous Phil]

Howdy!

The only 1911 I own is a .45 Auto Ordnance 1911A1 GI Specs. The gun hasn't seen that many rounds yet, somewhere around 1000, and I haven't modified anything so far to just let it break in. I just cleaned and lubed it a couple of times, but without disassembling the lower.

The system is based on a Series 80 with a firing pin block. Due to its really awful trigger, I ordered a conversion shim (0.057") at Brownells and removed the pin block device yesterday. Everything looked good to me and the trigger improved very much.

But now, when I engage the thumb safety and pull the trigger with some force, the safety snaps down and the hammer falls. This happens not all the time, sometimes it seems secure.

I already disassembled and reassembled it a second time with the same result. I cannot exclude a 100% that this wasn't already an issue before the conversion. But I try to avoid reassembling those two finicky lever parts... What can cause this failure, what do I have to look for? Can it be an error in assembly? I can take and post pictures if that helps to find the problem.

Any advice would be much appreciated!

Phil

 

[Blackfoot]

Does the safety work if you leave the shim out ?  (don't forget to also remove the parts that are in the slide)

Blackfoot

Edited April 17, 2023 by Blackfoot
added

[Equanimous Phil]

51 minutes ago, Blackfoot said:

Does the safety work if you leave the shim out ?  (don't forget to also remove the parts that are in the slide)

I will try without the shim. The firing pin block and its spring is removed.

Don't know if that matters: the gun still has its original springs (recoil, hammer, 3-leaf, firing pin). Besides polishing the trigger parts, ordering and replacing the springs will be the next step. I was surprised how stiff the firing spring and hammer spring are!

[Garrison Joe]

Easiest first step might just to be to get a new thumb safety and replace the factory one.   The engagement surfaces on the thumb safety are an intricate shape and can be worn or damaged without giving a hint to the operator.   I found that out on my Colt, attempting to make my own extended lever on the safety way back when extended safeties first showed up.   After fiddling with trying to figure out how I had made it fail to hold, I just replaced it with a new thumb safety.

The recoil, MAINspring and firing pin springs are pretty heavy from the factory in many 1911s.   Even the 3-leg sear/trigger spring can be heavy.  Replacing those is part of the work in tuning the 1911 for action sports like WB.

For the 150-160 Power Factor loads, I like a 15# recoil spring, 19# mainspring, and a high-end sear spring (those can be lightened to ease off the trigger pull with judicious bending) in my Colt 1911s.  I also install a lighter mag release button spring.  Honing the mainspring housing spring bore with a Flexihone (Brownells has them in the right size) usually helps that lighter mainspring run without dragging in it's channel.    Try to lighten the recoil spring weight in concert with lightening the mainspring, since they work real well when they provide somewhat balanced amounts of combined spring forces storing and releasing the energy of a recoil cycle.

You will need the thumb safety to work to pass a major match inspection of the safety.  But, of course, we never use it "in action" in WB.

I have not done the shim-plate trick to eliminate the firing pin lock.   Make sure that the plate is not interfering with normal travel of other fire control parts, which might put extreme pressure on the thumb safety causing it rapid wear or deformation.   Look for new wear on either the plate or any part that can contact it - bright metal areas might give you a clue as to the root cause of the safety failing.

good luck, GJ

  

Edited April 17, 2023 by Garrison Joe

[Equanimous Phil]

17 minutes ago, Garrison Joe said:

Easiest first step might just to be to get a new thumb safety and replace the factory one.   The engagement surfaces on the thumb safety are an intricate shape and can be worn or damaged without giving a hint to the operator.   I found that out on my Colt, attempting to make my own extended lever on the safety way back when extended safeties first showed up.   After fiddling with trying to figure out how I had made it fail to hold, I just replaced it with a new thumb safety.  

Yes, probably the easiest thing to do. I will check with my local gun shops if they have matching a standard thumb safety on stock (gun has to stay Traditional legal). But I have to place an order anyway, because ...

26 minutes ago, Garrison Joe said:

The recoil, MAINspring and firing pin springs are pretty heavy from the factory in many 1911s.   Even the 3-leg sear/trigger spring can be heavy.  Replacing those is part of the work in tuning the 1911 for action sports like WB.

For the 150-160 Power Factor loads, I like a 15# recoil spring, 19# mainspring, and a high-end sear spring (those can be lightened to ease off the trigger pull with judicious bending) in my Colt 1911s.  I also install a lighter mag release button spring.  Honing the mainspring housing spring bore with a Flexihone (Brownells has them in the right size) usually helps that lighter mainspring run without dragging in it's channel.    Try to lighten the recoil spring weight in concert with lightening the mainspring, since they work real well when they provide somewhat balanced amounts of combined spring forces storing and releasing the energy of a recoil cycle.  

... I have to order a couple of new springs, and the Flexihone tool. Many thanks for giving me a start what to buy! I just checked at Brownells for firing pin springs, they don't list the stiffness... Do you have a recommendation, Wolff, Wilson Combat, ...?

Btw, the ammo I currently shoot is tailored to make 170 PF (suitable for IPSC Classic Division Major), but not chronoed with my gun yet.

38 minutes ago, Garrison Joe said:

You will need the thumb safety to work to pass a major match inspection of the safety.  But, of course, we never use it "in action" in WB.  

If there is a thumb safety on a gun I want it to be functional when I take it to the range!

41 minutes ago, Garrison Joe said:

I have not done the shim-plate trick to eliminate the firing pin lock.   Make sure that the plate is not interfering with normal travel of other fire control parts, which might put extreme pressure on the thumb safety causing it rapid wear or deformation.   Look for new wear on either the plate or any part that can contact it - bright metal areas might give you a clue as to the root cause of the safety failing.  

I will check the parts for marks. But it happened immediately after the installing and not shot yet, so probably not much to find yet. As written before, I will try it un-shimed with the gap and see what happens.

Thank you very much for your inputs!!

[Garrison Joe]

Never have gotten very "wound up" about concerns over the firing pin spring strength.  😉 

Get a quality one and it will run longer than the other springs you put in the gun.  Sure would not pay through the nose for a different spring than most good makers supply.

The FP spring really only gets troublesome for two things.

Too light, and a dropped gun with live round in chamber and no FP interlock might have a very small chance of firing.

Too heavy, and in an especially light-mainspring gun, you might have primers fail to fire.   But I've not seen that.  Usually just the FP bore needs to be cleaned out when FTF happens.

good luck, GJ

Edited April 18, 2023 by Garrison Joe

[Deacon KC]

Wolff makes a complete spring pack that is really convenient. Any time I pick up a "new" [used] 1911, one of those kits goes in it.

[Equanimous Phil]

Put the gun on the workbench yesterday, removed the shim, and reassemled. No difference. Safety snaps off most of the time when pulling trigger. Gonna place an order for a new thumb safety (and new springs), and wait for the package to arrive...