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M1A/M1 Trigger modifications-Beware..

This is a discussion on M1A/M1 Trigger modifications-Beware.. within the Art Luppino forums, part of the Gun Professionals category; Most M1A's and M1's, as issued, had what can be described as an awful triggers pull, this can be improved upon with a good stone ...

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Old January 10th, 2017, 09:07 AM   #1
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M1A/M1 Trigger modifications-Beware..

Most M1A's and M1's, as issued, had what can be described as an awful triggers pull, this can be improved upon with a good stone and a little oil for it.

This is not a "How to" thread, be rather a warning about modifing the hammer hooks.

If you plan, and most people can do the work, to improve your trigger by stoneing the hammer hooks be certain you know the difference between which are the front hooks and which are the rear hooks before you start.

Never allow anybody to mess with the front hooks that is not experienced. These hooks must remain even or you will have a real problem your hands... Many hammers have ruined messing with wrong hooks along with more rounds going off than you intended..


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Old January 10th, 2017, 04:24 PM   #2
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I completely agree with Art, don't mess with the front hooks, or with what I call the 'sear lugs' near the middle of the trigger. The angles and edges on those guys are quite picky. I wouldn't even try to 'smooth' or 'polish' them - they're probably fine as-is anyway.

With the hammer fully cocked and trigger fully forward, the REAR hooks are the ones nearer to the rear of the rifle, and very close to the triangle gizmo at the top of the trigger. The FRONT hooks are the other ones - and they are in contact with the 'sear lugs' near the middle of the trigger.

The rear hooks do 2 functions -
1) They get 'caught' underneath the triangle gizmo and function as the 'disconnector' to prevent the hammer from falling when the bolt goes forward.
2) They determine the length of trigger movement during the 1st stage of trigger pull. And that movement determines how much actual 2nd stage 'sear engagement' remains before the hammer is released.
The 2nd stage BEGINS when the triangle gizmo touches the rear hooks, because the spring action of the gizmo adds addition weight to the trigger pull.

The front hooks also do 2 functions -
1) With the hammer ALL the back and the rear hooks UNDER the tri-giz, as the trigger is allowed to move slightly forward the giz releases the rear hooks, and the hammer MUST BE Caught by the sear lugs and the front hooks - that's called the 'hand-off' from the rear hooks to the front hooks.
When you slowly allow the trigger to move forward, you can hear and feel the click. Don't try to 'hold' the trigger in that position - let it move fully forward for the next shot.
2) The front hooks provide the total sear engagement that holds the hammer in 'cocked' position. With the trigger fully forward there is full sear engagement. As the trigger is moved thru the 1st stage the sear engagement decreases until there is only a small amount remaining at the beginning of the 2nd stage.
NOTE that the movement during the 1st stage is NOT 'take-up' or 'slack' - it is fully functional sear engagement reduction.

Jay Kosta
Endwell NY USA

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Old January 11th, 2017, 08:47 AM   #3
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Although I wouldn't ever consider altering the sear engagement [front hooks/trigger] to any degree in terms of angle or pitch, a flat parallelogram shaped hard Arkansas stone makes it a snap to remove the parkerization and mirror polish the surfaces without removing the surface hardness (that would be real BAD). I would strongly recommend against any stone that is more abrasive, and keep in mind that in this case "very SLOW is fast enough!"

[Stone should be on a bench edge or other surface, NOT in HAND.... apply sear surfaces to stone by hand using care not to tilt/pitch in any direction. It is very easy to feel the proper trigger surface alignment on the stone, not so much with the hammer...use more care/caution.

A well used hammer/trigger pair that's still in spec often sports this treatment by virtue of "lots 'o trigger-time".

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Old April 2nd, 2017, 12:36 PM   #4
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Purchased my LRB M14SA in 2014 and the trigger was just under 5lbs. according to the NRA weight system, but seemed a bit gritty in the pull. It is GI SA and replaced springs with Tubbs springs and made a huge difference in smoothness and did reduce the pull weight by a bit. While installing the new springs took the opportunity to make sure no grit or crud in there and cleaned it thoroughly and with the Tubbs springs is a very functional trigger group. Have observed over the years shooters constantly "working" on their triggers for the M1A/M14 and those same shooters constantly complaining about having problems with their triggers, duh!! Often hear that they just can't shoot a rifle with more than a 2lb. trigger pull. Well, they need to switch to a bolt gun for such a trigger in the M1A/M14 would not be safe to me. People with a lot more knowledge of such triggers than me, John Garand comes to mind, designed an excellent trigger for the M1Garand and M14 so who am I to start "adjusting" it.

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Old April 2nd, 2017, 12:49 PM   #5
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It takes a special trigger group to get a bolt gun trigger pull in the M14.

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Old April 2nd, 2017, 12:49 PM   #6
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Yup, I learned the hard way that even a factory SAI "NM trigger job" can lead to a ruined hammer and all sorts of defective function, like the auto-double-tap feature LOL! It was only rectified by an unmolested vintage USGI hammer with unaltered hooks, and fixing some bad factory bedding under the trigger housing wings. I got no better groups with the so-called NM trigger job, over the stock USGI hammer, either...unless you count the wild fliers from the uncontrolled doubles from the NM hammer mod...in which case the USGI hammer helps make better groups because you get to CHOOSE when the bullets will come out of the gun LOL!!

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