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Thumb Safety On 1911 Mk Iv Not Very Effective?


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#1 walmark

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Posted 14 May 2011 - 07:49 PM

I have a quick question. I just picked up a second hand Mk IV 1911. It's all nice, but the flip up safety doesn't seem very good. When the gun is racked and cocked, even with the safety engaged fully up if I squeeze the grip safety and press the trigger hard enough (harder than during normal shooting) the hammer will drop and the gun will shoot. Only once, since the safety will prevent the slide from racking and will just lead to all gas leaking out, but still. It shouldn't do that, right? What might be wrong with it and how can I fix it?

Also, bonus question: the front and rear sight appear adjustable for windage (but not elevation). The rear has a visible hex screw to hold it in place. What about the front?

Thanks!

Edited by walmark, 14 May 2011 - 08:47 PM.


#2 gcw360

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Posted 14 May 2011 - 07:56 PM

View Postwalmark, on 14 May 2011 - 07:49 PM, said:

I have a quick question. I just picked up a second hand Mk IV 1911. It's all nice, but the flip up safety doesn't seem very good. When the gun is racked and cocked, even with the safety engaged fully up if I squeeze the grip safety and press the trigger hard enough (harder than during normal shooting) the hammer will drop and the gun will shoot. Only once, since the safety will prevent the slide from racking and will just lead to all gas leaking out, but still. It shouldn't do that, right? What might be wrong with it and how can I fix it?

Also, bonus question: the front and rear sight appear adjustable for windage (but not elevation). The rear has a visible hex screw to hold it in place. What about the front?

Thanks!

If I were you I would get a replacement ASAP from where you bought it.  That should not be happening. The sights are not adjustable, FYI.

#3 walmark

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Posted 14 May 2011 - 08:33 PM

Thanks for your response. Interesting about the sights, I was sure they are adjustable by the looks of them.

I cannot return/replace the pistol as I got it used at a discount from a private party. I'm more interested in what is wrong with the safety and how can I repair it. And when I mean safety, I mean the ambidextrous thumb safety, NOT the grip safety. The grip safety works fine but the ambidextrous thumb safety can be overcome by pressing trigger hard when the gun is cocked and thumb safety is engaged all the way up. You can see it come down slightly as I pull the trigger - enough to release the hammer but not enough for the slide to move backwards.

#4 walmark

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Posted 15 May 2011 - 11:07 AM

So I proceeded with disassembling the gun to find the culprit. Now I'm no expert, but I think the problem lies with the left thumb safety lever pinion:

Attached File  IMG_0145.jpg   117.1K   12 downloads

When you look at the shaft you can see that there is a spot worn out where it connects to the trigger (?) sear.

Attached File  IMG_0147.jpg   134.43K   12 downloads

The sear seems to be made of brass or some other metal obviously much stronger than the safety pinion as there is no visible wear on that one.

Do you think I could get a replacement thumb safety? How to make sure it doesn't wear off like the previous one? Also, when I disassembled the mechanism I found a lot of grease that appeared to be silicone. Is that part of the gun supposed to be heavily greased? Or did someone overdid it?

Thanks to all who can help.

#5 walmark

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Posted 19 May 2011 - 06:51 PM

I replaced the left thumb safety and for now it seems like it temporarily solved the issue. I say temporarily because when you engage the (new) safety and press the trigger, you can see it "trying" to make its way back down. For now it holds, but I believe it's only a matter of (short) time before the metal wears off and the safety fails like the original one. Unless the problem is somewhere else...?

Anyone else with Mk IV or other M1911 PTPs encountered this issue? Any comments appreciated.

#6 gcw360

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Posted 19 May 2011 - 07:31 PM

I have a MK IV and have not encountered this.  1000 or so rounds through the gun to date.

#7 walmark

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Posted 02 June 2011 - 06:40 PM

Well, the replacement thumb safety lasted for a little over 2 weeks. Now it's back to dropping down when the trigger is pressed a little harder. I guess the "metal" it's made of is of really poor quality if it wears down that fast. I guess I won't be fixing it again...

I'm still wondering though - why is it doing that? Was it poorly designed? Or is there some other problem here?

#8 Brick Stone

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Posted 19 October 2012 - 05:45 AM

NECRO POST REVIVAL  - It might be that the person who sold it to you had done some work on it and did not assemble it properly.  They knew it and dumped it.

It could very well be that when you are operating the piece,   parts that shouldn't be engaging actually are.    One factor might be that the trigger parts and other bits that react to and with the mainspring are not where they should be.

You are correct as well about the metal being of poor quality though.   Upon removal of the left thumb safety of my NEW MKIV,  it tore off leaving the post behind.   I had not used too much pressure in the attempt to remove it either.  

You are correct in assuming that this should not happen.




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