Installed New Hammer--Now Thumb Safety Gets Stuck...

brockgl · December 9, 2008, 11:27 AM

I installed some new parts on my stainless Springfield Mil-Spec 1911 last night, and I am having a problem with my thumb safety.

A beavertail(http://www.brownells.com/aspx/NS/sto...0GRIP%20SAFETY)

A new hammer (http://www.midwayusa.com/eproductpag...eitemid=496392)

And a new trigger (http://www.midwayusa.com/eproductpag...eitemid=777797)

I have on order a new sear, but have not yet installed it, so it isn't causing the problem (though it may be the solution?... http://www.midwayusa.com/eproductpag...eitemid=528378)

I modified the frame on my Springer Mil-Spec, which was a lot easier than I thought. I debated whether or not to do it, since I only had a dremel, but I went ahead and went for it since the metal I was going to remove was superficial to the function of the gun. The beavertail is now installed, and the frame looks great! I am totally satisfied with my dremel job, and I really lucked out and don't seem to have made any stupid mistakes there.

The hammer practically dropped in, it was rubbing against the sides of the frame some, so I polished the sides of it a bit, and it now moves freely.

The trigger also required a little bit of metal to be sanded off to be able to fit into the gun, but it also is now installed and moving freely.

The sear I am currently using is my stock sear, though the one that Wilson makes to mate with this hammer and trigger is ordered and on the way.

Here is the problem.

The sear and disconnect install fine, as does the hammer (it seems), the beavertail slides into place and allows me to insert the thumb safety all the way until I try to put the safety's lug into the gun. I got it to go all the way in once, but the whole trigger group locked up, and I really had to work everything hard to break it loose and remove it. Now I can't even get it back in.

I am assuming that the thumb safety needs to have a bit of metal grinded off, but I am not sure what part to make smaller.

I am also having another problem:

When the sear/disconnect, hammer, and beavertail are installed, the hammer will not 'cock' all the way to the rear. It looks like it goes back far enough, but it doesn't go back far enough to allow the slide to clear it, and the slide won't go back. It doesn't look like the beavertail is catching it, I would be more inclined to think it is the sear, but any suggestions would be great!!

I am getting my new sear tomorrow, so I am not going to grind on stuff until I get the sear and give it a go. But any suggestions would be awesome!

Thanks!

brickeyee · December 9, 2008, 12:14 PM

Thumb safeties require fitting to the sear, hammer, and frame.

There are a number of places (blind hog is one) that have directions.

It is done with files and stones to remove as little metal as possible for correct function.

The stud on the thumb safety block the seer from moving away from the hammer sear step/shelf and allowing the hammer to fall.

the tolerances are about zero, wince the sear only needs to move a couple hundredths of an inch to release the hammer (the shelf on the hammer is about 0.020 deep).

brockgl · December 9, 2008, 09:54 PM

I tested each part in succession with the hammer (first just the sear/disconnect, then the thumb safety, then the thumb safety WITH the grip safety.)

The hammer moved freely all the way back when just the sear/disconnect was installed. But I could not fully install the thumb-safety, and since I had not put the grip-safety on yet I was able to see inside the frame revealing what was causing the thumb safety to get stuck. There was a hefty amount of material on the thumb-safety notch that wouldn't let it clear the sear. I filed it down a little at a time, and it finally cleared. It's still a bit tight, but I'm going to mess with it some more tomorrow.

With the thumb-safety installed, the hammer WOULD travel far enough backwards to allow the slide to clear. So, I knew the problem with the hammer not traveling back far enough had to be with the grip-safety. This turned out to be true. On an upper part of the grip-safety there was a part (the corner where the grip-safety makes a 90 degree angle) that the hammer was pressing against. Filing off about a millimeter of this allowed the hammer to move backward far enough for the slide to clear.

This new hammer, for some reason, seems to be tighter to the slide than my original. It's almost like I've installed a stronger spring, because it's forward pressure feels stronger (though I haven't changed any springs).

For example, when I pull back the slide (when the hammer is fully cocked) the hammer isn't low enough to clear the slide until the slide hits the hammer and pushes it down and out of the way. The spring tension the hammer has against the bottom of the slide seems stronger than the factory hammer did (though it still has more available downward movement, so it isn't metal blocking it, but it feels like spring tension).

Another example of this strong hammer tension is when the hammer is dropped and fully resting against the slide. It puts more forward pressure against the slide than I remembered. I noticed this when I tried to take the barrel bushing off of the front of the slide. The bushing is noticeably tighter due to the hammer pushing the slide forward. Also, once the bushing is off the barrel is somewhat tight and resting in a downward position against the bottom of the slide. When I pull back the hammer, this tightness is completely released.

Is this normal? Is it possible I just never noticed it before? Or is it something I should try to remedy?

**Unclenick** · December 10, 2008, 01:29 AM

Well, a 1911 is fun partly because you can look and see what is happening. It is also the case that it is easy for a beginner to create an unsafe trigger group in a number of ways. The best thing would be to get some instruction in building 1911's. Short of that, at least get a copy of Kuhnhausen's book on the 1911 and read through the inspection points. I think I chewed up three sears and two hammers learning to do trigger work, but I was lucky enough to get some expert advice on mistakes I'd made.

The thumb safety is fairly trivial to deal with. Take the gun down to the frame, including removing the thumb safety and slide stop detent spring and plunger. Then put the trigger, sear, disconnector, and leaf spring back in. Slide the mainspring housing into place to keep the leaf spring in position, but don't bother putting the assembly pin in. Now you can see down into the frame, so put the original thumb safety in and observe how it rotates up to block the sear, and down to give it clearance to move. Next, put your new thumb safety in and note the differences. You can easily see where it needs to be reduced by filing along its circumference. Usually it is just at the portion that does the actual blocking. You reduce that until it doesn't rub the sear at all, and even in safe position has at least a thousandth or two of clearance. You want only the detent to offer any resistance. That safety needs to operate quickly and without rubbing.

Different hammers have the hammer strut holes located slightly differently in relation to the hammer pin hole or at a different number of degrees around from the hammer hooks. This changes the mechanical advantage and/or the degree of mainspring compression acting on the hammer. That is why a different hammer can apply more pressure to the slide even with all the other components being unchanged. Target hammers, like the Gold Cup hammer, do just the opposite. They reduce the mechanical advantage so there is less hammer hook pressure on the sear in the cocked position, making a lighter target trigger release easier to obtain.

A problem that can happen when the hammer is pushed beyond the cocking point by the slide is that when the slide goes forward the hook can drop hard enough onto the sear nose to bounce off of it, deflecting it forward, then falling to half-cock rather than staying in full cock. The usual treatment is to file the hammer nose down where it contacts the bottom of the slide when the slide is cycling. You keep filing that spot until the slide just pushes the hammer far enough to let the sear engage and just slightly farther (to allow for pin slop and wear). Then, when the slide goes forward, the hammer barely moves as the hammer hook comes to rest on the sear nose. That is gentle on the engagement and extends the life of a trigger job.

The grip safety extension (arm), as you discovered, almost always needs fitting if it is a custom grade part. Usually this is just filing the bottom of the step in the end of the extension until the trigger bow slides under it when you grip the safety. The tip sometimes also needs filing down if it actually touches or rubs the back of the trigger bow when you are not gripping it. A couple of thousandths clearance between it and the trigger bow is desirable when you are not gripping the safety. You still cannot move the trigger enough to cause a discharge in that condition, but the grip safety operates freely.

WESHOOT2 · December 10, 2008, 09:02 AM

Some parts 'install'; some parts get fit.

Savior: "The Colt .45 Automatic, a Shop Manual" by Jerry Kuhnhausen.

brockgl · December 11, 2008, 08:47 AM

Project finished! Pictures at this thread: http://thefiringline.com/forums/show...56#post3176556

brickeyee · December 11, 2008, 11:05 AM

I hope you ran all the action checks to make sure everything works correctly, especially the safeties.

brockgl · December 11, 2008, 11:35 PM

I have brickeyee, but are there a list of safety checks that you recommend running before deeming a gun safe/reliable for carry?

December 9, 2008, 11:27 AM	#1
brockgl Senior Member Join Date: October 28, 2002 Posts: 246	Installed New Hammer--Now Thumb Safety Gets Stuck... I installed some new parts on my stainless Springfield Mil-Spec 1911 last night, and I am having a problem with my thumb safety. A beavertail(http://www.brownells.com/aspx/NS/sto...0GRIP%20SAFETY) A new hammer (http://www.midwayusa.com/eproductpag...eitemid=496392) And a new trigger (http://www.midwayusa.com/eproductpag...eitemid=777797) I have on order a new sear, but have not yet installed it, so it isn't causing the problem (though it may be the solution?... http://www.midwayusa.com/eproductpag...eitemid=528378) I modified the frame on my Springer Mil-Spec, which was a lot easier than I thought. I debated whether or not to do it, since I only had a dremel, but I went ahead and went for it since the metal I was going to remove was superficial to the function of the gun. The beavertail is now installed, and the frame looks great! I am totally satisfied with my dremel job, and I really lucked out and don't seem to have made any stupid mistakes there. The hammer practically dropped in, it was rubbing against the sides of the frame some, so I polished the sides of it a bit, and it now moves freely. The trigger also required a little bit of metal to be sanded off to be able to fit into the gun, but it also is now installed and moving freely. The sear I am currently using is my stock sear, though the one that Wilson makes to mate with this hammer and trigger is ordered and on the way. Here is the problem. The sear and disconnect install fine, as does the hammer (it seems), the beavertail slides into place and allows me to insert the thumb safety all the way until I try to put the safety's lug into the gun. I got it to go all the way in once, but the whole trigger group locked up, and I really had to work everything hard to break it loose and remove it. Now I can't even get it back in. I am assuming that the thumb safety needs to have a bit of metal grinded off, but I am not sure what part to make smaller. I am also having another problem: When the sear/disconnect, hammer, and beavertail are installed, the hammer will not 'cock' all the way to the rear. It looks like it goes back far enough, but it doesn't go back far enough to allow the slide to clear it, and the slide won't go back. It doesn't look like the beavertail is catching it, I would be more inclined to think it is the sear, but any suggestions would be great!! I am getting my new sear tomorrow, so I am not going to grind on stuff until I get the sear and give it a go. But any suggestions would be awesome! Thanks!

December 10, 2008, 01:29 AM	#4
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	Well, a 1911 is fun partly because you can look and see what is happening. It is also the case that it is easy for a beginner to create an unsafe trigger group in a number of ways. The best thing would be to get some instruction in building 1911's. Short of that, at least get a copy of Kuhnhausen's book on the 1911 and read through the inspection points. I think I chewed up three sears and two hammers learning to do trigger work, but I was lucky enough to get some expert advice on mistakes I'd made. The thumb safety is fairly trivial to deal with. Take the gun down to the frame, including removing the thumb safety and slide stop detent spring and plunger. Then put the trigger, sear, disconnector, and leaf spring back in. Slide the mainspring housing into place to keep the leaf spring in position, but don't bother putting the assembly pin in. Now you can see down into the frame, so put the original thumb safety in and observe how it rotates up to block the sear, and down to give it clearance to move. Next, put your new thumb safety in and note the differences. You can easily see where it needs to be reduced by filing along its circumference. Usually it is just at the portion that does the actual blocking. You reduce that until it doesn't rub the sear at all, and even in safe position has at least a thousandth or two of clearance. You want only the detent to offer any resistance. That safety needs to operate quickly and without rubbing. Different hammers have the hammer strut holes located slightly differently in relation to the hammer pin hole or at a different number of degrees around from the hammer hooks. This changes the mechanical advantage and/or the degree of mainspring compression acting on the hammer. That is why a different hammer can apply more pressure to the slide even with all the other components being unchanged. Target hammers, like the Gold Cup hammer, do just the opposite. They reduce the mechanical advantage so there is less hammer hook pressure on the sear in the cocked position, making a lighter target trigger release easier to obtain. A problem that can happen when the hammer is pushed beyond the cocking point by the slide is that when the slide goes forward the hook can drop hard enough onto the sear nose to bounce off of it, deflecting it forward, then falling to half-cock rather than staying in full cock. The usual treatment is to file the hammer nose down where it contacts the bottom of the slide when the slide is cycling. You keep filing that spot until the slide just pushes the hammer far enough to let the sear engage and just slightly farther (to allow for pin slop and wear). Then, when the slide goes forward, the hammer barely moves as the hammer hook comes to rest on the sear nose. That is gentle on the engagement and extends the life of a trigger job. The grip safety extension (arm), as you discovered, almost always needs fitting if it is a custom grade part. Usually this is just filing the bottom of the step in the end of the extension until the trigger bow slides under it when you grip the safety. The tip sometimes also needs filing down if it actually touches or rubs the back of the trigger bow when you are not gripping it. A couple of thousandths clearance between it and the trigger bow is desirable when you are not gripping the safety. You still cannot move the trigger enough to cause a discharge in that condition, but the grip safety operates freely. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

December 10, 2008, 09:02 AM	#5
WESHOOT2 Senior Member Join Date: February 20, 1999 Location: home on the range; Vermont (Caspian country) Posts: 14,324	nothing ever drops in Some parts 'install'; some parts get fit. Savior: "The Colt .45 Automatic, a Shop Manual" by Jerry Kuhnhausen. __________________ . "all my ammo is mostly retired factory ammo"

December 9, 2008, 12:14 PM	#2
brickeyee Senior Member Join Date: December 29, 2004 Posts: 3,351	Thumb safeties require fitting to the sear, hammer, and frame. There are a number of places (blind hog is one) that have directions. It is done with files and stones to remove as little metal as possible for correct function. The stud on the thumb safety block the seer from moving away from the hammer sear step/shelf and allowing the hammer to fall. the tolerances are about zero, wince the sear only needs to move a couple hundredths of an inch to release the hammer (the shelf on the hammer is about 0.020 deep).

December 9, 2008, 09:54 PM	#3
brockgl Senior Member Join Date: October 28, 2002 Posts: 246	I tested each part in succession with the hammer (first just the sear/disconnect, then the thumb safety, then the thumb safety WITH the grip safety.) The hammer moved freely all the way back when just the sear/disconnect was installed. But I could not fully install the thumb-safety, and since I had not put the grip-safety on yet I was able to see inside the frame revealing what was causing the thumb safety to get stuck. There was a hefty amount of material on the thumb-safety notch that wouldn't let it clear the sear. I filed it down a little at a time, and it finally cleared. It's still a bit tight, but I'm going to mess with it some more tomorrow. With the thumb-safety installed, the hammer WOULD travel far enough backwards to allow the slide to clear. So, I knew the problem with the hammer not traveling back far enough had to be with the grip-safety. This turned out to be true. On an upper part of the grip-safety there was a part (the corner where the grip-safety makes a 90 degree angle) that the hammer was pressing against. Filing off about a millimeter of this allowed the hammer to move backward far enough for the slide to clear. This new hammer, for some reason, seems to be tighter to the slide than my original. It's almost like I've installed a stronger spring, because it's forward pressure feels stronger (though I haven't changed any springs). For example, when I pull back the slide (when the hammer is fully cocked) the hammer isn't low enough to clear the slide until the slide hits the hammer and pushes it down and out of the way. The spring tension the hammer has against the bottom of the slide seems stronger than the factory hammer did (though it still has more available downward movement, so it isn't metal blocking it, but it feels like spring tension). Another example of this strong hammer tension is when the hammer is dropped and fully resting against the slide. It puts more forward pressure against the slide than I remembered. I noticed this when I tried to take the barrel bushing off of the front of the slide. The bushing is noticeably tighter due to the hammer pushing the slide forward. Also, once the bushing is off the barrel is somewhat tight and resting in a downward position against the bottom of the slide. When I pull back the hammer, this tightness is completely released. Is this normal? Is it possible I just never noticed it before? Or is it something I should try to remedy?

December 11, 2008, 08:47 AM	#6
brockgl Senior Member Join Date: October 28, 2002 Posts: 246	Project finished! Pictures at this thread: http://thefiringline.com/forums/show...56#post3176556

December 11, 2008, 11:05 AM	#7
brickeyee Senior Member Join Date: December 29, 2004 Posts: 3,351	I hope you ran all the action checks to make sure everything works correctly, especially the safeties.

December 11, 2008, 11:35 PM	#8
brockgl Senior Member Join Date: October 28, 2002 Posts: 246	I have brickeyee, but are there a list of safety checks that you recommend running before deeming a gun safe/reliable for carry?