Hammer problem on milspec

[Jammer Six]

More problems with my Springfield milspec.

I got the hammer strut replaced, after all my research, it turned out to be easy.

So then, at the league on Thursday night, I had three failure to feeds, all incomplete return to batteries in two hundred rounds.

Since I have close to six thousand rounds through this weapon, and everything I've seen says that I should change the recoil spring after 2,500, I put in a new recoil spring, a Wolfe stock 16.5 lb. I figured that since it was feeding, and just not returning completely to battery, it just wasn't being pushed hard enough anymore.

Then, today at the range, the hammer started following.

Once in a while, after firing a round, the hammer would drop to half cock.

It would also drop to half cock every time the slide was dropped from slide lock. (At the range, I only tried it two or three times.)

So I came home, read everything I could find in Kuhnhausen, bothered people on the phone, took the weapon down, studied the hammer and sear on exterior pins on the frame under a magnifying glass, marked the engagement with magic markers, and studied it some more.

When I cocked the weapon, thumb safety off, grip safety depressed, and tried to push the hammer forward with my thumb, it held rock solid.

Cocking it, off safe, holding the grip safety in, and tapping it on the tang, same thing. Rock solid.

The safeties all check out. With the thumb safety on, the hammer won't drop, no matter what you do. Same thing with the grip safety.

Cycling the weapon with the trigger and grip safety depressed, no problem. The disconnector is disconnecting.

However, with the weapon off safe, cocking the hammer with my thumb, and pulling it beyond full cock (which depresses the thumb safety) will drop the hammer to half cock nine out of ten times.

I noticed, in my travels and studies, that Kuhnhausen recommends an egagement of .020 for match weapons and .025 for carry weapons.

The most accurate way I could devise for measuring the engagement was to set a feeler gauge flat across the base of the full cock notch on the hammer, and feel with fingernails to see if the gauge was higher than the hammer hooks or if the hooks were higher than the gauge. Not very accurate, at least it didn't feel like it was very accurate, but it looks to me like I have right at .020 engagement.

Everything looks OK to me. The witness marks generated by dry firing after coloring the engagement surfaces with a permanent marker are even- it's engaging across the entire surface.

Then, on a hunch, I dug the old recoil spring out of the garbage, and re-installed it.

I then dropped it from slide lock 100 times, with no following. Not one.

Then I put the new spring, and dropped the slide another 100 times, and the hammer dropped to half cock 22 times.

I'm at the limits of what I know.

The only thing I can think of is that the slide is slamming forward harder with the new recoil spring, (duh...) and the difference is enough to bounce the sear out of the notch.

If that's the case, why won't if bounce off when the grip safety is held down, the tang is bounced on the bench?

Isn't a jar a jar?

I haven't touched this sear and hammer, although it was polished way back when I first owned this weapon, well over 5,000 rounds ago.

What's next? What else should I try?

Would it always drop to half cock when it was cocked beyond full cock, and I just noticed?

Sear spring? Melt it down to a puddle of slag?

Thanks, guys.

 

[stans]

First, quit dropping the slide on an empty chamber. Dropping that slide can cause the sear to bounce and ruin the engagement surfaces. It sounds like there is too little spring tension on the sear and/or the engagement surfaces have been damaged. Hammer and sear engagement is something for a gunsmith who is well versed in the 1911.

 

[bountyhunter]

Then, on a hunch, I dug the old recoil spring out of the garbage, and re-installed it.

I agree with stans. It is possible the sear spring (left most tang) is not applying enough pressure. You can bend it a bit too increase it, but that is typically a temporary fix for this kind of problem. Overall, I'd wager the 6000 rounds of usage have worn the sear face just enough that the primary cut is not capturing the hammer reliably. Any gunsmith can fix this.

 

[Jammer Six]

I changed the mainspring first, and that solved 90% of the problem. I have the ILS, and the new mainspring was considerably longer than the old one, and eliminated the problem when the weapon cycled.

The problem when you pull the hammer past full cock remained, however.

So I studied Kuhnhausen some more, and looked over the hammer and sear under good light with a magnifying glass. The hammer hooks did indeed look ever so slightly rounded over, and I did my best on an Arkansas soft stone to get them square. I also made them a couple thousandths deeper, they were right at .020, and now they're just a hair deeper. Kuhnhausen recommends .025 for carry weapons, so I figure it's all right. Better too deep than not deep enough is what it sounds like to me.

I then added a secondary angle to the sear, and all the problems were gone.

I went to the range, and loaded one round a dozen times, and two rounds twenty times, and fired 200 rounds without a single malfunction.

Now the only problem I see is that before I left for the range, I covered the engagement faces of the hammer hooks and the sear with permanent marker, and when I tore it down after I got home, the witness marks are all on one side- only one hook appears to be carrying the load.

I don't see how you'd customize the angle of the sear, it's supposed to be straight, isn't it?

The only thing I can think of is to stone just the one hook until both hooks show witness marks. The only way I can see that this would be so would be if the pins aren't parallel, which would seem to indicate that the holes in the frame aren't exactly right.

It looks to me like you have to customize each hammer and sear to a particular frame, because the holes will never be perfect.

I have the external pins, and I can set the sear and hammer up on them and gaze at them, but I don't see how to use them to guide the stoning.

Am I headed in the right direction?

It also seems that some of what Blindhog calls "creep" has developed, and the pull feels heavier.

I have a set of trigger weights coming, and I'm going to go get a stone with a sharper right angle on it tomorrow, as well as finer.

And I'm not going to drink so damn much coffee before I stone sears...

 

[Rich in VA]

You GOTTA have a jig, unless you're prepared to ruin quite a few hammers and sears. I would recommend either the Marvel or the Power Custom I. You also need a good set of stones, India, black Arkansas, and ceramic. You can get them in a set from Brownell's.

Sounds like your hooks aren't square or your sear's not square, or both. The creep that you feel is probably caused by the deepened hooks, plus the whole set needs to be polished.

You CAN customize the sear angle with the Power jig, not as easy with the Marvel.

You can spend money on sears and hammers a lot, or spend money on a good jig and set of stones once..

Here's a link for doing a proper trigger job with a Power I jig.

http://www.brownells.com/aspx/NS/GunTech/NewsletterArchive.aspx?p=0&t=1&i=349

or, in .pdf version

http://www.brownells.com/aspx/NS/GunTech/NewsletterArchive.aspx?p=0&t=2&i=349

Rich (always the student) in VA

 

[stans]

I agree, it is almost impossible to due a proper trigger job without a jig. The other alternative is to buy hammer and sear sets that have been "pre-tuned", also known as "drop in trigger jobs".

 

[Jammer Six]

I have a jig on the way, I chose Ed Brown's jig.

I'm going to investigate stones tomorrow morning.

 

[Rich in VA]

That jig will only do the sear, and is really just a holder so that you can set up the sear with the .020 gauge, a la Kuhnhausen........

Oh, well.....

R