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Posted: 9/11/2010 3:20:16 PM EDT
I did my first take-down field strip of my M1A today (I rarely get to shoot it, so aside of barrel and bore cleaning, including anything else I can reach, I have never taken it down and cleaned it out, greased it [bad I know], etc).

Everything went flawless until the very end.  After I did my extreme cleaning of everything, and applied my own grease in the sweet spots, I reassembled the rifle.

During my function test, everything goes well except:

Moving the op rod back, is very smooth and perfect, as it always has been.  Upon doing a dry fire afterward, and then pulling the op rod back again, I have a large amount of tension and have to put a small amount of force to get it to lock the bolt back and charge the rifle for another fire.

I can observe on the side the action part of the trigger group that strikes and rear of the bolt, and it is what seems to be giving the tension when pulling the op rod back, after it is fired.  Once I pull it back and it is locked back into its pre-fire place, there is no tension whatsoever and the op-rod and bolt move smoothly again.

I took down the rifle again and observed for anything out of the ordinary, or at least what I know to be ordinary, and I could see nothing.  Upon reassembly, I ran into the same issue again.

Apologies if some of my nomenclature is off, but I hope I described it to the point that you can tell me what is wrong, if anything.

To my knowledge, I'm 99.9% sure the rifle never had that kind of tension before, when I charged it after a dry fire, but I could be wrong as it was not something I did often.

*edit*

I went back and repeated the above a few times, charge, dry fire, etc, and it seems to not be as tense as I originally thought.  So is this the norm for the rifle after you dry fire?  I honestly do not remember how it was in the past as I did it maybe two times in the past year.
Link Posted: 9/11/2010 3:29:24 PM EDT
[#1]
After you drop the hammer (the piece you're seeing smack the bolt), you have to overcome the force of the hammer spring to retract the bolt.



As this happens, the hammer is caught by the sear, and stays there until released by the trigger.
Link Posted: 9/11/2010 3:34:08 PM EDT
[#2]
Ah, so what I'm feeling is normal?

I suspected so after I went back and tried the third time, seeing as I have only ever dry fired it a couple times in the past.
Link Posted: 9/11/2010 3:37:58 PM EDT
[#3]
There's a concave cut on the top of the hammer that might like a little grease, as well as the bottom of the bolt body.



That may cut down on some of the effort, those surfaces are what cam against each other to cock the hammer.
Link Posted: 9/11/2010 7:02:07 PM EDT
[#4]
You can have a trigger job which will include smoothing the hammer etc.... but what you are feeling is normal
Link Posted: 9/11/2010 10:49:24 PM EDT
[#5]
Did you put the operating rod spring guide in upside down?
Can you insert a magazine and will it lock in place?
Link Posted: 9/12/2010 12:47:17 AM EDT
[#6]
I put the spring guide in correctly, as when I took it all apart, I put the parts down in the directions they were facing when I did so, to ensure I did not mess up like that.

As for locking a mag into place, I'll try that once I get off work, am about to leave the house.
Link Posted: 9/12/2010 7:29:43 AM EDT
[#7]
What you are describing sounds normal.  You should put a small amount of grease on the hammer where it should be showing a small bit of wear.  Also grease the underside of the bolt as these are the two parts that rub against one another when the rifle is fired and the hammer re-cocked.  This should smooth out that tension some.
Link Posted: 9/12/2010 2:53:16 PM EDT
[#8]
Quoted:
What you are describing sounds normal.  You should put a small amount of grease on the hammer where it should be showing a small bit of wear.  Also grease the underside of the bolt as these are the two parts that rub against one another when the rifle is fired and the hammer re-cocked.  This should smooth out that tension some.


I greased the underside of the bolt on first, before making the post here, however I just did the hammer spot that showed a little wear, but it still has the resistance.  I guess that is normal, because once I pull the op rod back and release, and try again it is very easy.  I must just have not noticed it before.
Link Posted: 9/13/2010 5:04:48 AM EDT
[#9]
The resistance you are feeling comes from the hammer bearing on the firing pin. The firing pin has a bevel that corresponds to the bevel on the bridge in the reciever that cams the firing pin back. The reason you don't feel it after it is cocked, is that the hammer isn't impinging on the firing pin, then.



This bridge in the reciever is there to prevent out of battery ignition. It blocks the firing pin until the bolt is turned to the locked position. This is also one of the parts of the reciever that can be easily out of spec.



If the force is extreme, it is possible that you have a bit of stack up of tolerance. I've seen bridges and firing pins with very little chamfer. I just ran into this problem with an M-1. If you know what you're doing and are good with a file (need a diamond file, really) you can CAREFULLY increase the size of the chamfer on the firing pin "foot" so as to allow it to properly cam over the reciever bridge. It is inadvisable to file on the reciever because it is the more expensive part.



Do not go to far as you will negate the blocking effect of the reciever bridge and risk out of battery firing.



I recomend Khunhausen's book on the M-14.
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