Hammer falling to half cock?

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cavman

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Was out with a couple of new shooters today. We were using both of my 1911 wadcutters.

One of them was getting an occasional half cock hammer in the middle of shooting a string. The round was in place but the hammer was at half cock. The other gun was fine as normal.

If happened about 8-9 times out of ~200 rounds.

I don't think it was a too strong of a spring problem (ie never reaching full cock, because they were ejecting okay, but that is just a first guess) I just took the whole thing apart right now, and I realize that everything looks okay to my eyes, so time to call THR.

I will check Jerry Khunhausen's book to see if I can find anything there.

Any ideas?
 
Assuming the gun is reasonably clean with no chips, slag, detritus in the hammer / sear area. Also assuming you have a lightweight trigger installed.
1, Examine carefully the sear / hammer engagement points for wear, rounding, chips etc.
2, Increase slightly the tension on the sear engagement spring.
It is generally not recommended to go below 3# pull weight on a 1911. It can be done by a really good 1911 smith but commonly what happens is the shooter will get the hammer falling to half cock occasionally or frequently.

good luck and I hope its an easy fix. Jerry Kuhnhausen is da man!

Roger
 
I would not recommend going below 3 1/2 pounds if you intend to shoot full power ball ammo with a full power recoil spring.

3 pounds is O.K. for light target loads only, and lighter recoil springs used with it.

Try removing the mag with the slide locked back and then release the slide lock.

If the hammer follows to the safety intercept notch, you have a problem.

If it doesn't, the problem your friend was having was somehow shooter induced due to a loose grip letting the gun bounce in his hand and tripping the trigger partially again.

Should the hammer follow on the empty gun slide drop, you may need to increase the bend on the flat sear spring.
Or you may already have damaged hammer hooks or sear surface and need a trigger job or replacement parts.

rc
 
Thanks rcmodel and velocette

I have tried the slide lock suggestion and can't get the hammer to follow about 50 times.

The trigger weight on the one with the issue is a bit lighter than when I weighed it earlier this summer. It comes in at 3.0 lbs-3.25 lbs. (it passed earlier weight pull at 3.5#)

These are target loads though not super light. ~4.3 gr Bullseye under 200gr LSWC

I will play with sear spring and bring up to ~3.5#.

I looked at the sear notch on the hammer using a 30x loupe, and they looked "fine" to me but I am not very knowledgeable here to know what to really look for.

It makes me think it might not be only shooter induced as it happened to my friend and his younger cousin, both; mostly him but she also had it happen once.
 
Ive been going threw this in a way also and im finding its a real balancing act to get it right without having a real heavy trigger pull.

What recoil spring weight you using? The heavier it is the more likley ive found the hammer will follow.
Also you may want to pay attention to the grip the shooter is using. If its a really high grip that can push the grip safety up just a tad but still work, But it will be up enough it could make the grip safety contact the hammer and not allow the hammer to set.
So id check the hammer and grip safety clearance at full cock and if they touch.

I like a very heavy recoil spring and i can occasionally get a hammer follow with an unloaded gun if i use a high grip hold and the grip safety hits the hammer. I purposely have to try and make it happen with an unloaded gun, It wont do it with it loaded and firing as the chambering slows the slide down alot to make it non issue.

I increased my sear spring tension a tad so its about a 5lb pull which is perfect for ccw, And gives me even more margin for the hammer not to follow the slide now. But i could get 3lb trigger pull if i went with a 18lb recoil spring.

Mine started when i put a new hammer on the gun as this was never an issue with the old hammer and the 22lb recoil spring. Luckily my gun is blued so ive been taking my Dremel to the grip safety cup the hammer lay back into and deepening it for more clearance. Its hard metal and my cheap battery operated Dremel is taking me forever to grind enough out to help get me to the point i cant purposely make the hammer follow on an empty gun.

IMO and empty gun will do it much easier than a loaded and firing gun due to the slide being slowed down, If thats not your case i think id be looking more into the hammer and sear surfaces.
 
One of them was getting an occasional half cock hammer in the middle of shooting a string. The round was in place but the hammer was at half cock. The other gun was fine as normal.
Click to expand...

I think you have a worn sear. That half cock saved someone from a slamfire due to the hammer following the slide.

I would replace the sear and the hammer.
 
Thanks Slamfire.

I just checked with the 30x loupe and could see the 2 sear angles clearly and could see no wear.

I increase the sear leaf spring tension, so now the trigger is weighing in at 3.5lbs-3.75lbs.

I think that is all I can do now until I can get out and do some shooting and see if I can reproduce the hammer follow.
 
Just curious, did the malfunction occur in your hands or the new shooters hands. A light grip can cause this as well as ejection problems. I had this problem with a Randall that came with a very heavy trigger, (not pull wise but trigger mass wise) I went to a Wilson aluminum trigger and the problem went away.
 
shimitup: I have been racking my brain, and perhaps on one of the hammer falls it occurred in my hands...but I am not totally positive. It definitely occurred in both new shooters' hands, however.

I'll give the middle leaf a little tweek forward as well, but this leaf is not one that I have ever played with before.

1911tuner give a little description here that helps http://forum.m1911.org/showthread.php?t=1011&page=1&pp=10 so I think I understand what is trying to be accomplished
 
Success! Now can make the hammer fall to FIRE

success, (sort of) at least I can make it happen when I want.

update: was shooting a match on Saturday and had a follow to half cock. shot a few more and after the fourth of five, it "doubled" and fired the fifth automatically.

Today I have it totally clean, and have been playing around the the 30x loupe and the camera looking at the hammer hooks.However the pics were of marginal to good quality only and haven't posted them. Hammer hooks don't look that bad to me (no chips etc.) but there is maybe a little rounding at their very top.

Anyways, I just tried 1911Turner suggestion. I held the trigger and racked and then brought forward the slide. Nothing happened like the 100 times before.

Unless I REALLY brought it forward! If I bring it really hard forward, the hammer will fall all the way. I have been able to repeat this now four or five time out of 10 attempts.

Regardless of what I see/don't see under the loupe, is it most likely the hammer hooks? Or is there some trigger bow action here that is causing the disconnector to work?
 
It is most likely worn hammer hooks. If they have been prepped for a proper trigger job they are most likely .018 to .020 tall. IF they are worn and become slightly negative they will not keep positive engagement with the sear. Regardless if the sear looks to be proper, the hooks only need to be a little over 90 degrees to want to follow.

You can set up the hammer and sear on the right side of the gun using the respective pins and it will let you see an *approximate* orientation of the parts. Once set up that way you can then see if the parts have positive engagement. If it is positive the hammer should move slightly rearward before falling. Apply tension with your thumb to simulate the main spring.

You didn't mention what kind of trigger is in the gun. If the parts were much less positive to neutral AND you are using a heavy steel trigger, it wouldn't take much hook wear to turn the trigger group negative and thus trigger bounce could create hammer follow.

Cheers
Mac.
 
I agree. I think you are right.

Should I be looking at the trigger?

Should I be looking at the mainspring being too weak?

Should I go back to the middle finger of the sear spring and add more tension even though when I did before it didn't seem to work?

Any suggestions?
Thanks
 
I'd be checking the sear for free movement and to see if the top of the disconnect spade contacts the bottoms of the sear feet, which would restrict both parts. Adding tension to the left leg of the sear spring may help keep it from falling all the way down...but you still need to address the reason that it's following in the first place.

Does it follow the slide when the trigger is held rearward? If it does, then go back to worn/negative hammer hook engagement.

Does it (only) follow when the trigger isn't pulled? If that's the case, it may well be a simple matter of the trigger bumping the disconnect, and adding tension to the center leg could cure it. As Mac noted, a heavy steel trigger makes trigger bounce more likely to occur.
 
I have done all the 1911 safety checks, hammer, sear, disconnect, thumb safety, grip safety etc., that the manual shows.

The only one that will cause the hammer to fall all the way down (or rather, at all) to the firing pin is when holding the trigger fully rearwards, I bring the slide back and then SLAM it forward. The trigger then will fall all the way. Just letting the slide drop naturally will not get the hammer to fall. I really have to drive the slide forward.

Do we think that it is only worn hammer hooks? What about the half cock interceptor notch. For that not catching it, there must be something else there as well, no?

In any case can I take the hammer hook squaring file and make a few passes? http://www.brownells.com/.aspx/pid=848/Product/1911_AUTO_HAMMER_SQUARING_FILE

Or is an entirely new hammer needed?

edited to add: Trigger. I have the Greider trigger. It is a long 3-hole lightweight. http://www.brownells.com/.aspx/pid=20228/Product/GREIDER_PRECISION_1911_AUTO_V_SERIES_MATCH_TRIGGER
 
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Following all the way down with the trigger held back indicates that the hammer hooks aren't holding onto the sear. They're either worn or the sear is failing to properly reset, and grabbing the hooks at the very tips...and jarring off as the slide goes home.

Let it slam with the trigger pulled and check to see if the trigger action is extremely light.
If it is, the sear isn't resetting completely.

There's also a chance that the sear itself is too short, and the hook/sear crown angles don't mate up properly when the hammer is at full cock. Instead of the hammer hooks sitting on the sear primary angle, they grab it to the rear. If the sear has an escape cut, the effect is much the same as the hooks worn to a negative engagement angle.

Re-squaring negative hammer hooks alters the sear/hammer interfact geometry. It may help temporarily, but the problem will return...or it may make it worse from the git-go.

Best WAG is that this isn't a problem that will be cured without new parts, and having a qualified triggersmith set them up to insure correct geometry.

Most of the time, these issues are simple. Sometimes they're not....
 
Thanks 1911Tuner. Your comments are much appreciated. I will give this one up and pass to a trigger guy. I think I have taken this analysis and repair as far as I can go.
 
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