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Posted: 5/3/2003 2:59:48 PM EDT
Well I decided that before dropping $150+ for an aftermarket trigger, I'd give the "15 minute trigger job" a shot.

Still not a match trigger, but MUCH better!

I do have a question though. Normally I think of pulling the trigger in a firearm as simply separating the sear engagement points until the hammer drops.

I noticed on my Bushy however that as you pull the trigger, during the creep phase when the sear surfaces are separating, the hammer actually travels backwards a small amount. This means that instead of just sliding the sear surfaces apart, you are actually pushing back against the hammer spring.

Is this normal, or is it possible to do some filing to eliminate this ?

Thanks in advance for your help.

Link Posted: 5/3/2003 3:54:01 PM EDT
Normal. Don't mess with it.

Tweak (I think) years ago posted a message that described this as "positive engagement" or some such. Haven't seen it mentioned since.

Link Posted: 5/3/2003 4:02:36 PM EDT
Is this normal, or is it possible to do some filing to eliminate this ?   Yes, Yes. What you are seeing is that there is a 'reverse angle' cut into the hammer. It is there to insure that the sear grips it positively. Decrease this angle too much and the trigger will fire (slip off the hammer) when you release it. The hammer should hold the cocked position when you drop (under recoil spring tension) the bolt on an empty chamber. Close the bolt, pull the trigger, and see if it 'clicks'. Filing off the hard surface on the hammer will subject it to wear. If it's soft enough that you can file it, (not stone or grind it), then it probably will wear anyway. I would have another hammer on standby before I started. The cost of a few ruined parts could be more than what a good 'smith would charge to adjust it, but, you have to pay to learn!! Good luck.
Link Posted: 5/3/2003 5:13:11 PM EDT
You are dead-on on that one rimfire. I gave my trigger the 15 minute special and it was greatly improved over broken in at 3k rounds, but I couldn't leave it alone and decided to put a "tinky" (.004"-.006") radius on the trigger. BAD MOVE! That was just enough that the hammer would fall 2 out of 5 times doing the hold the trigger and release slow test. There was a gun show in mesquite today so I purchased a new trigger and the problem went away. The amazing thing is that the new trigger(I sorted through 6)is now smoother than the one that I originally honed. It cost me 16 bucks for a new trigger, but then again I learned something and have a trigger job that would have cost me $ 50+ bucks at the gunsmith.
Leave that reverse angle alone, it serves a good function to the firearms dependability as well as safety.
Link Posted: 5/3/2003 9:57:30 PM EDT
Are you sure it was only the trigger? Removing .006 from the trigger shouldn't cause it to malfunction.  Did you also radius the hammer while you were at it?
Link Posted: 5/4/2003 6:01:00 AM EDT
Everything that I have [i]read[/i] in the past recommends against removing material on a stock AR trigger. It has something to do with that the sear surfaces are plated and not hardened, and once you remove material, you are removing the hard plating. [i]Polishing[i] the sear surfaces and the pins may improve your trigger pull.
Link Posted: 5/4/2003 6:50:55 AM EDT
Thanks for the good info guys.

For a follow up question to the original post,
do ALL AR15 triggers work this way ?

In other words, do aftermarket single stage and/or two stage triggers have this "hammer reverse" action as well ?


Link Posted: 5/4/2003 6:25:49 PM EDT
As author of the 15 Minute Practical Trigger Job I appreciate the kind comments.

FrankSquid is correct... the sear surfaces are hardened, and removing material will likely go through that SURFACE hardening.  That is why I recommended only the fine polishing with the compound.  Really what we are doing here is just removing anything really gross, and lightly lapping the hammer to the trigger.

The second important thing is, no angles were changed.  Yes, the main improvment comes from the lighter springs.  The stock M16 springs are way much stiffer than needed.  With the semi auto AR15, we are more concerned with accurate fire, good trigger control.  We are not so concerned with extreme conditions, vibration from full auto fire, etc.

Most importantly, the method is simple, and reversable.  I have had NO reports of any problems other than a few FTF with some types of surplus ammo. With ammo of any quality, no problems.  And if you insist on firing this ammo, you can drop in new springs (cost $3).

Full sear engagement is maintained, no safety compromises.  No angles are ground.  We don't want shooter100's problem.  

The method is repeatable, and easily doable by others, with the same results.

If it were not for all of these factors, I would not have printed this up for all to try.

I ask you all this... if you try this method, do no other modifications.  If you do additional modifications, please do not claim to have done the "15  Minute Practical AR-15 Trigger Job".
Link Posted: 5/4/2003 7:05:53 PM EDT
A_Free_Man, THANKS for your excellent advise!
I did your 15 minute trigger job and was extremely pleased. Then I improvised with oversize pins, it got even better. Just had to tell you, thanks for the money you saved me and others.
Link Posted: 5/4/2003 8:12:43 PM EDT
Yes, the main improvment comes from the lighter springs.
View Quote
Where does one get lighter springs?

Link Posted: 5/4/2003 8:20:33 PM EDT
The "15 Minute Practical AR-15 Trigger Job" intrigues me.  Where can I find a more thorough explanation of this?

Link Posted: 5/4/2003 8:29:48 PM EDT

Boomer, this should answer both questions.

Thanks, danc46
Link Posted: 5/5/2003 7:36:38 PM EDT
Thanks for the info. I have it book marked.

Link Posted: 5/6/2003 11:07:06 AM EDT
You can also by reduced-power springs from JP.  I think Brownells has them too.

Ed, I suspect one of the things the aftermarket triggers do is play with those angles and things.   JP's looks like stock, but I'm sure the difference between a 4lb trigger and a 10lb trigger is not visible just by looking at it.  I know the JARD trigger has a completely different sear arrangement.   The 2-stage trigger obviously have to have some extra stuff to get the second stage.
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