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 direction for insertion of trigger & hammer pins on AR-15 lower
wpshooter  [Member]
11/29/2009 9:19:33 AM EST
I have some trigger & hammer cross pins for an AR-15 lower.

The pins have 2 small "cuts" in them. One cut is about 1/8 of an inch from one end of the pin and the other cut is about mid-ways the length of the pin.

Does it make a difference on which side of the lower receiver that the pins are inserted from, i.e. do the "cuts" in the pins need to be positioned on either the right side or the left side of the trigger and hammer assemblies ?

Can someone tell me what the function of these cuts are ?

I have looked at some directions for assembling a lower and they do not seem to mention these "cuts" in the pins or what they are for.

Thanks.
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rhaney02  [Team Member]
11/29/2009 9:25:20 AM EST
Doesn't matter one way or the other. I have seen factory assembled rifles with them going both ways.
LastRites  [Member]
11/29/2009 10:28:26 AM EST
The cut's or grooves in the pins are for the legs of the springs to ride in so that the pins don't walk out of your lower while firing.
forever4  [Team Member]
11/29/2009 12:46:31 PM EST
As was said, the groove is for the springs to lock into. Since the spring is on both sides, doesn't matter which side the grove is on. Remember, these things were mass produced to be simple and as easy as possible to assemble. KISS, idiot proof, etc.
hotdog250j  [Team Member]
11/29/2009 1:39:00 PM EST
it SHOULDNT matter
it USUALLY doesnt matter,
however, i had a lower that the trigger pin would "walk" out about half the thickness of the reciever, and i'd just push it back.
for no reason i reversed that pin and it fixed it.
dont now why, dont care.
Steve_M  [Team Member]
11/29/2009 2:23:40 PM EST
OCD and the Black Rifle,
I'm compelled/possessed to install from right to left with the groove near the end to the right.

other times , as long as the right spring hits the right groove and seats, it doesn't matter.
GHPorter  [Team Member]
11/29/2009 4:11:17 PM EST
When building a lower, you should observe two rules about the trigger and hammer pins:

1. Put both pins in in the same direction.
By inserting the smooth end first, you skip any "catch" of the hammer's "J" spring on the side groove, which is a BIG deal when you're trying to be careful.

2. Insert the pins with the grooved end LAST.
By inserting them both the same way, you can actually see which end has the groove by which side the hammer spring is caught in the trigger pin. This is a big deal when you go to remove either or both the hammer and trigger, because it's a really, REALLY big deal when you have to use a punch to remove a pin and then find out that half-way out the pin catches on the hammer's "J" spring.

Other than that, there is no practical difference between inserting the pins from either side.
Ridge_Runner_5  [Team Member]
11/29/2009 4:29:14 PM EST
I do it right to left simply because the lower is facing that way so I can install the bolt catch...
Quentin  [Member]
11/30/2009 8:30:35 AM EST
Originally Posted By GHPorter:
When building a lower, you should observe two rules about the trigger and hammer pins:

1. Put both pins in in the same direction.
By inserting the smooth end first, you skip any "catch" of the hammer's "J" spring on the side groove, which is a BIG deal when you're trying to be careful.

2. Insert the pins with the grooved end LAST.
By inserting them both the same way, you can actually see which end has the groove by which side the hammer spring is caught in the trigger pin. This is a big deal when you go to remove either or both the hammer and trigger, because it's a really, REALLY big deal when you have to use a punch to remove a pin and then find out that half-way out the pin catches on the hammer's "J" spring.

Other than that, there is no practical difference between inserting the pins from either side.


GHPorter is 100% right, might as well do it smart like he suggests. It will be much easier removing the hammer pin by first looking at the trigger pin and knowing which way to tap it out and avoid getting stuck again on the J-spring. I think Brownells suggests doing it this way as well.

wpshooter  [Member]
12/1/2009 12:08:33 AM EST
Yes, in looking at the pins and a trigger and hammer assembly, it appears that the groove in the MIDDLE of the pin is supposed to wind up in the CENTER of the trigger and hammer assembles to keep the pins from slipping. So the LONG end of the pin should be inserted FIRST but which side of the lower they are inserted from makes NO difference as long as the LONG end is inserted FIRST.

Thanks.
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