After reading the question from Grim_Reaper about his heavy gritty trigger and the reply suggesting he try the "15 minute trigger job", I went to work on my trigger.
Felt great dry firing it, but at the range I got a three shot burst.  It would have emptied the magazine had I loaded more rounds.
So, my question is.....what did I do wrong?
Does this have to do with the lighter hammer or the trigger spring modification?
And about the hammer, what's the hook on the back of the stock hammer for.  The one that I ground off per the "15 min. trigger job" instructions.
Anyone else have a good experience with the "15 min. trigger job"?  

The hook is for your disconnector to engage the hammer.  I am not too familiar with the 15 inute trigger job so I can say what is wrong.  

Most of the time, I just polish the two pins holding the hammer and the trigger to get a better feel, I was always told AR trigger job are not recommanded since all the parts are harden, and any polishing or grounding can remove the harden surface and cause the metal to wear off.

Without the hook, you are slam firing. Very dangerous. Get a new hammer NOW.

The AFreeMan 15 minute trigger job is great. I don't recall any instructions to grind off the hook. I have seen other trigger jobs that recommend grinding down the back of the hammer, though.

Another quickie: Use standard fire control parts and get a set of JP reduced power springs ($10) from Brownell's.

No, the disconnector hook was not supposed to be modified.  The UPPER rear part of the hammer, may be removed, it's only purpose is the spur which catches on the autosear of the M16.  Since with our AR15's we have neither the autosear nor the spur, that part of the hammer is unnessary.  Removing it will lighten the hammer and give faster lock time.

Dear Sir,
Since you are the gentleman that devised this "trigger job", let me ask you.  
Where do you suppose I went wrong, and what do you think I might replace to put it right.
By the way I ground off the upper "hook" not the disconector hook and thank you for explaining what it is for.  I knew it wasn't my problem as JP sells a hammer that looks quite a bit like what the stock hammer looks like when modified.
I have to admit the one area of the instructions that I didn't follow to the letter was the polishing.  I used AUTOSOL metal polish and dry fired it 30 times.  Do you suppose that I overpolished the sear?
Thank you for your help.
DCS

Some other trigger jobs can result in doubling.  Reducing the sear engagement, stoning the sear surfaces, or even changing the angles, can result in a less safe trigger.  My trigger job method does none of these.

I doubt you overpolished it.  Look for wear on the disconnector hook on the hammer, and wear on the disconnector itself.

Due to the lighter pull, you may not be pulling the trigger back firmly, and doing a "bump fire".  

The lighter springs and polishing in and of itself will not cause doubling, as there has been no change in sear engagement or geometry.

Examine the front top edge of the trigger.  Is it still sharp, and not rounded?  Look at the sear surfaces of the hammer.  Same here, a nice sharp edge?

A LEO friend had a doubling problem we traced to a very worn hammer and trigger.  New hammer, trigger and disconnector fixed it.

Let us know what you find.

Dear A_Free_Man,
What I found was that the (I don't know all the correct terminology for everything so bear with me) front upper edge of the trigger (where it contacts the hammer when hammer is cocked) is "dull" and not sharp, not even as sharp as the lower edge of it is and certainly not as sharp as it had been prior to my polishing it.
One thing about the trigger, it still takes a fair amount of travel before the hammer is released.
I wonder more about the hammer than the trigger.
When I ground the top front of the hammer as shown in the diagram, I felt like I had to take off an excessive amount of metal to get it to resemble the picture.  I wound up shortening the hammer a little to get it to look like the drawing.  
I wonder if the bolt isn't having enough contact with the hammer as it goes back and therefore the hammer isn't going back far enough for the disconnector to catch it.
Before I modified it, I could open the bolt by pulling back the charging handle and then release the bolt while holding the charging handle with the trigger pulled, when the bolt closed the hammer was still cocked.  Now if I try that same procedure, the hammer is uncocked when the bolt closes.
I'm only telling you this for your information, I'm going to a gun show tomorrow and buying a new trigger, hammer and disconnector.
But if anything I've said points to anything in particular, please let me know.
I wish I knew it was only the hammer, but since I don't I guess I'll replace it all.
Thank's for your input.
DCS

Now we are getting to the meat of the situation!

Good.  OK, apparently the polish you used was MUCH more coarse and rough on the surfaces than the very fine stuff I suggested.

Second, I don't understand about grinding the upper front of the hammer?  Why?  

But replacing the trigger and hammer, at this point, is necessary.  Also, as the disconnector is a cheap part, it can't hurt to replace it, too.  So, certainly do that.

OK, back to the hammer.  For some reason you took off material other than just the "tail" that formerly held the autosear.  Removing that tail is not necessary, but makes a for a little faster locktime.  But if other metal was removed, yes, it could cause the hammer not to go back enough to be captured by either the disconnector (if the trigger is held back) or the trigger/hammer sear surfaces, if the trigger is released.  Either way, this is not good!

Sorry there was confusion on this.  This time, just use the springs you previously modified, but do no polishing or hammer trimming, and see how everything works.  THEN, if you still feel a little grittiness in the trigger pull, polish as stated, with the polish I have listed.  You may sub another equally fine polish made for polishing plastics such as lexan and plexiglass on motorbike windshields and helmet face shields, airplane and helicopter windows, etc.  These types of polishes are VERY fine.

Then I am sure everything will work correctly for you.  

You ask why I ground off anything from the front of the hammer.  The reason is because step #2 of the hammer modification says to "Slightly angle the top of the hammer as shown in the illustration below" and in order to grind out the "step" at the top of the hammer and make it look like the drawing, I wound up taking metal away below that "step". Also, if you grind off the entire "hook" on the back of the hammer as the drawing shows, and then bevel the front top of the hammer, you wind up with a point where these two surfaces intersect.  Therefore, you, or rather, "I" had to grind the top of the hammer to have a flat on top of the hammer as shown in the illustration.
Suffice it to say, that "I" inspite of trying to follow the instructions, made a mess of things.
I will replace the trigger, hammer and disconnector.
I will take off the hook on the top back of the hammer but I think I'll leave out the step #2 of the hammer modification.
As for polish for the sear, I'll use rubbing compound this time.
I've learned a lot and I thank you for your input and help.
And,I guess you've learned that there are people out here that can screw up anything no matter how simple you try to make it for them.
Thanks again, DCS

Ahhh, that was not part of the original article I wrote.  That was added by another person, who has hosted it at another URL.

Here is my original:

[url]http://www.sargenthome.com/15_Minute_AR_Trigger_Job.htm[/url]

At my request, this one has been revised to restore it to the original article:

[url]http://www.geocities.com/molonlaberkba/triggerjob.html[/url]

This clears up my confusion.  This is exactly why KISS is best.

Freeman, can you show us the correct way to remove the upper portion of the rear of the hammer?  It is something I would like to do, but Im not sure of just how much of the "tail" to take off.  Thanks


Steven

NONE of what you read below has anything to do with my trigger job article.  This is a separate issue.  With that warning, read on:

The top front of the AR15 hammers many times have a notch that is troublesome.  In addition the bottom of the bolt carrier has a ramp cut, exposing the head of the firing pin.  What this is for is so that if the disconnector fails to capture the hammer on semi-auto fire, or if some numbnuts removed the disconnector for some reason, the hammer would catch on the firing pin head and the works would be tied up with the bolt open.

This also causes some problems otherwise.  The best way of dealing with the notch problem is to buy an unnotched hammer, rather than trying to smooth off a notched hammer.  I don't know who is selling unnotched right off.  I DO prefer the unnotched hammers.

But, the above has nothing to do with grinding off the tail.  The tail of the hammer (not the disconnector hook) was there to have a place to hang the autosear spur, which is not on the semi-auto AR15.  When you grind that off, be very careful not to hit the disconnector hook.  Two or three layers of tape is good insurance.

When I do this, I grind it off even with the back side just above the disconnector hook, so that the upper part of the hammer is about 1/4" or so thick from front to back.

This is best done with a Dremel fiber cuttoff wheel.  WEAR SAFETY GLASSES for all grinding operations.  Go slowly and dip the hammer in a cup of water often to keep it cool.  After the tail is removed, smooth the rough edges and touch up th whole thing with Birchwood Casey Touchup Blue.  Then rinse well with water, dry and oil it.

I would do this only on hammers used strictly for target use.  The reduced mass makes for faster locktime.

BUT, even if you do not remove the entire tail, it is sometimes useful to remove some of the tail.  I have seen some rifles that the tail of the hammer would strike the back of the disconnector.  You could see the shiny wear marks.  This is not good. More likely to see this on carbines.  Removing some of the tail will fix this.

[b]A_Free_Man[/b], is the notch (top front of trigger) you advise to trim the same that is required when swapping out to a 9mm upper?  I seem to remember the 9mm boys saying to cut off the notch, or ramp the bolt.

Just making sure I'm following you.

MG

I said exactly, "The best way of dealing with the notch problem is to buy an unnotched hammer, rather than trying to smooth off a notched hammer."

I am not advising you to trim the front of the hammer to remove the notch.  That has nothing to do with obtaining a smoother, lighter trigger for general shooting with the AR15.

A_Free_Man, I just did the trigger in my RRA...the one that had what felt like a 25lb trigger pull, and it made world of difference.  Not as creepy, and it feels like the pull was cut in half.  It's certainly not gonna be compared to the NM trigger, but I just needed to make this rifle pleasant to shoot.  The first time I took it out with the new RRA lower, I felt like I was on the verge of blowing a tendon in my wrist.  It was so bad that my buddy who was with refused to fire it after about 30 rounds hehehe.  

FWIW, I have a set of the reduced tension springs in another rifle, and those feel just a tad mushy.  They work fine, but I prefer the feel of the trigger I just did.  Thanks for the heads up on this one.  

Thank you, Fenian.  Have you encountered any ammo that did not fire with this trigger job?  I have only had one or two reports of this, and that was with imported ammo of questionable quality.  Everyone else reports OK.

Haven't had a chance to shoot it...literally, I just did it right before I made that earlier post.  I'm not anticipating any problems; the hammer strike feels stronger than the reduced tension spring set I used in the other rifle, and that one went bang all the time.  I don't know that I'm gonna be a good test case, though, since I pretty much stick to handloads of one kind or another in all my ARs.  

Most likely, I'll test this Wednsday night with some of the Hornady "blemished" FMJ bullets I got from Lock, Stock and Barrel a couple of weeks ago.  If I have any problems, I'll let you know.

Ok, My problem is solved thanks to much help from "A_Free_Man".
The problem was caused by my sloppily following an addition to the "15 minute trigger job" by someone other than "A_Free_Man".
It was the step that said "to slope the top front of the hammer so that it looked like the drawing shown". I wound up shortening the hammer and probably taking off too much off the front of the hammer in an effort to make my hammer look like the drawing.  I say it was my fault but in reality, I don't know how anyone could make a "notched" hammer look like the drawing without taking off as much as I did.
Anyway, what happens when this is done, is the bolt cannot push the hammer back far enough to engage the disconnector and with my finger holding the trigger back there was nothing to stop the hammer from slamming forward and firing the next round and so on until I ran out of ammo.
So, I replaced the hammer after grinding off only the upper hook and now it looks exactly like a "JP" lightened hammer and now it works just as it should and although I only fired 25 rounds today, I'm certain it is fixed and that there is no doubt that the lightened hammer will fire each round and there will be no misfires.
Thanks to all who replyed and Thanks again to A_Free_Man, he really seems to be a fine fellow and knows his stuff!
Sincerely, DCS

Hunduh, cannot respond to your email, your box is full.

Mailbox empty, sorry about that!!!

I'm glad I get a chance to thank A_Free_Man.
Your trigger job when closely followed, provides an exellent trigger for mine and a few of my friend's AR's.

I tried the tigger job to the letter and now my disconnector is hanging up.

Seems the little extra spring pressure kept everything going. A little off the disconnetor should make it work.

Anyone else have this problem.

BTW.  i am using DPMS parts kit in a Eagle lower.

I have not had this problem with the 15 minute trigger job, but after trying JP reduced power springs, I did get some problems with trigger reset. As you said, after the application of some 400 grit sandpaper and polishing with a dremel its seems to disconnect just fine.

That does bring me to another question, though. Is a felt pad (on a dremel) and white rouge too harsh to use on the contact/mating surfaces of the hammer and trigger?

OK got it working now. Took a little off the disconnector and baby this thing is sweet!

I, personally wouldn't "take a little off the disconnector".
I had an out of spec disconnector once, then went and bought a new one. One that is in spec.

Yes, keep the Dremel tool away from the hammer/trigger sear surfaces.  The method I gave you for polishing is all you need.  It just removed the grittiness, a sort of accelerated break-in.  The parts are lapped to each other.  That is all.  

I don't advise any other polishing or stoning on the AR15 hammer and trigger. The hardening of these parts is very shallow.

If you are looking for something better than these parts, you can go to the JP or another of the aftermarket fire control groups.

Disconnectors are stamped or sheared out of a piece of sheet metal.  They can be quite rough sometimes.  Look for disconnectors that have good square edges.

I am thinking about doing this on my Armalite. What about just polishing the surfaces and not messing with the springs?

Secondly, where do I get:

Small punch (for trigger/hammer pins)
Large soft punch (3/8” Delrin® rod or 3/8” wood dowel)
Fine compound (#7 rubbing compound or Kit Scratch Out plastic polish)

I just completed the trigger job on my Bushmaste M4. The trigger is much improved. Thanks. They didn't teach us that in aromorers school!

Great thread!

I was wondering what negative effects if any would be cause by not cutting the hammer spring?  I'm assuming the the pull will be a bit heavier but won't there be less chance of a light primer strike in the long run?

Is it posible to just put a slight bend on the hammer spring rather than cutting it?

I performed the 15 minute trigger job on my v-match and while it did make the trigger smoother and lighter, I did experience more than an acceptable number of light strikes (maybe 5-7 out of 50).  I was using my own reloads, but these were primed with CCI No. 41 ("NATO" sensitivity) primers.  At this point, I've pulled the old springs and put JP springs in and things seem to be working again.