Palmetto State Armory Detent Pins?

Red Rezin · #1 11-16-12, 12:56

I put together my first lower the other day and for the most part it was straight forward. The only part that I'm worried that might be wrong is the orientation of the detent pins on the pivot and takedown pins.

The problem is that the PSA detent pins have both a rounded and a sharper cone like side. In all instruction videos they say to put the "rounded side" toward the takedown pins. But most other detent pins look like one side is flat, the other rounded. I guessed that the rounded side was supposed to be the flat side, and the agressive sharp side was supposed to be the "rounded".

Does anyone know if I installed the more aggressive pointy side of the detent pin toward the takedown pins if this was backwards?

The pivot pin has been extremely hard to get in and out (slowly getting better) and still needs to be punched out gently. Worried I got the detent pin backwards. The takedown is much easier to move than the pivot.

Thanks for your advice, just want to make sure this was correct.

Red Rezin · #2 11-16-12, 13:13

Forgot to mention concern #2 - the safety selector.

For some reason even with the hammer cocked back, it was nearly impossible to get the safety selector through the receiver all the way. I could squirm it through by hand on the left side, but then it wouldnt line up on the right. The bottom part of the trigger assembly had just enough metal high enough to block an easy push through. After marring up my reciever a bit trying to muscle it through, I ended up with a hammer and eventually was able to get the selector to seat all the way through.

It seemed like maybe the bottom piece of the trigger was out of spec - getting in the way by less than a MM. But now that it is in, the safety seems to function properly.

Is this normal? Any risks by forcing it in?

Thanks - my first lower build, not sure what is normal. These are the two unusual issues I had with this PSA lower kit.

jb1911 · #3 11-16-12, 13:24

I would think that the pointed end of the detent pin goes toward the spring and the rounded end towards the take down pin. The detent pin slides along the groove in the take down pin when it moves back and forth, rounded is better.

Troy9749 · #4 11-16-12, 13:38

I've used a few psa parts kits and always put the sharp point in first. Never had trouble with a safety, sorry, can't help on that one.

polymorpheous · #5 11-16-12, 13:41

Could be your lower receiver is slightly out of tolerance or on the high side of tolerance.
What lower did you install the parts kit in?

Red Rezin · #6 11-16-12, 13:57

The lower is a LAR Grizzly, I'd be surprised if it was the reciever - it looked visually like the two holes lined up properly, just a bit of the trigger base higher than it should be - barely. Is there any risk that I installed the trigger incorrectly? It function checks, I don't see how I could have impacted the height of the base trigger part. It just worries me a bit as it seems like it should slide right through and I forced it in there.

As for the detent pin, too bad there are no instructions on this from PSA.

I'm with you guys, the round side should probably touch the pin which is what I was afraid of... I just thought perhaps the pointed side made sure it would hold positively and not loosen on accident, especially since it was the taller end. Still hoping to get an official answer from PSA. It makes me curious why they made their detent this way? Confusing for first timers. Maybe the pointy side is supposed to keep spring more secure? Looks like its back to youtube/brownells to figure out how to reverse the pivot pin install...

polymorpheous · #7 11-16-12, 14:56

Quote:

Originally Posted by Red Rezin

The lower is a LAR Grizzly, I'd be surprised if it was the reciever - it looked visually like the two holes lined up properly, just a bit of the trigger base higher than it should be - barely. Is there any risk that I installed the trigger incorrectly? It function checks, I don't see how I could have impacted the height of the base trigger part. It just worries me a bit as it seems like it should slide right through and I forced it in there.

As for the detent pin, too bad there are no instructions on this from PSA.

I'm with you guys, the round side should probably touch the pin which is what I was afraid of... I just thought perhaps the pointed side made sure it would hold positively and not loosen on accident, especially since it was the taller end. Still hoping to get an official answer from PSA. It makes me curious why they made their detent this way? Confusing for first timers. Maybe the pointy side is supposed to keep spring more secure? Looks like its back to youtube/brownells to figure out how to reverse the pivot pin install...

The holes in the receiver may line up, but are they to spec?
http://www.quarterbore.com/store/ar15receiver.jpg

RD62 · #8 11-16-12, 15:12

Are the pivot and take down pins functioning properly? Does the lower pass a function/safety check? If yes to these and the manipulation of the weapon is not negatively effected I'd not worry about it.

Red Rezin · #9 11-16-12, 15:51

Quote:

Originally Posted by polymorpheous

The holes in the receiver may line up, but are they to spec?
http://www.quarterbore.com/store/ar15receiver.jpg

Hah, I'm not sure I could tell anything from that image, horrible quality.

But I get what you are saying, I'll have to find a better image and see if I have precise enough tools to measure that small of a deviation. I guess the answer is that something is out of spec - obviously not normal - but not enough where I wasn't able to force it in. Hopefully no functional problem can happen down the line due to the tight fit. Mainly concerned about pressure on the trigger from the safety selector switch.

"Are the pivot and take down pins functioning properly? Does the lower pass a function/safety check? If yes to these and the manipulation of the weapon is not negatively effected I'd not worry about it."

Function/safety seems to work, other than I cant manually pull out the pivot pin without something to punch it out. Originally it felt like it would never move it was so tight, not sure if this is due to the detent pin or just the receiver/pivot pin being very tight. I imagine over time the metal will wear and make it smoother. Only, if it's installed backwards, that might be the problem.

I'm hoping to find the official answer though in case someone else runs into this during their build. If it doesn't matter which direction, that will help put me at ease.

AFshirt · #10 11-16-12, 17:52

That sounds perfectly normal to me. I have an entire vault of M4s that you can tell how old and used they are based off of how easy it is to pull the two pins out.

Iraqgunz · #11 11-16-12, 17:58

I may be wrong about this, but I remember some batches of those lowers being out of spec and they were being sold off at gun shows.

I also don't remember detent pins being different. They were designed so that one could insert them either way. Maybe I am getting Alzheimer's in my old age.

polymorpheous · #12 11-16-12, 18:01

Quote:

Originally Posted by Iraqgunz

I may be wrong about this, but I remember some batches of those lowers being out of spec and they were being sold off at gun shows.

I also don't remember detent pins being different. They were designed so that one could insert them either way. Maybe I am getting Alzheimer's in my old age.

No.
You are absolutely correct.

I wouldn't be so worried about the takedown and pivot pin detents as much as I would be about the FCG holes.

Troy9749 · #13 11-17-12, 09:43

Last night I pulled a takedown detent out of the last lower I built with a PSA kit, flipped it, and put it back together. No difference in function, so IMHO I wouldn't worry about that. And those takedown pins are really tight too.

Do you have another rifle you could swap the fire control group with to see which component is causing the problem via process of elimination?

Good luck.

jet66 · #14 11-17-12, 09:54

I've put in two PSA LPKs, never paid attention to the orientation of the detent pins. Takedown and pivots on both work just fine, with no more or less noticeable difference in tension than either of my factory assembled Colts. I suppose I could have scored a perfectly lucky 4/4 in putting them 'round end out,' but it's more likely that it's just not that critical.

jb1911 · #15 11-17-12, 13:16

You're supposed to intall the safety selector first, then with the selector set to fire, install the FCG.

polymorpheous · #16 11-17-12, 15:01

Quote:

Originally Posted by jb1911

You're supposed to intall the safety selector first, then with the selector set to fire, install the FCG.

Not according to the TM-05538C-23&P/2

jb1911 · #17 11-17-12, 18:40

Quote:

Originally Posted by polymorpheous

Not according to the TM-05538C-23&P/2

Admit it, my way is better.

polymorpheous · #18 11-17-12, 18:51

We are all very impressed, I'm sure.

All bullshit aside...
This is not the board to sling misinformation.

If that order of assembly works for you, fine.
But speaking in absolutes, telling the OP he is "supposed" to do it a certain way, when in fact depot level armorer's technical manuals state otherwise.

Sometimes you think you know something, other times you KNOW you know something.

C4IGrant · #19 11-17-12, 19:03

Quote:

Originally Posted by jb1911

Admit it, my way is better.

Your way is really a crap shoot. The reason is because of tolerance staking. Some triggers will NOT fit into the lower with the selector in place.

If using GI FCG, I typically drop the trigger in and then install the selector. Then put in the trigger pin, hammer and hammer pin.

C4

jb1911 · #20 11-17-12, 19:38

Quote:

Originally Posted by C4IGrant

Your way is really a crap shoot. The reason is because of tolerance staking. Some triggers will NOT fit into the lower with the selector in place.

If using GI FCG, I typically drop the trigger in and then install the selector. Then put in the trigger pin, hammer and hammer pin.

C4

The reason some triggers will not fit into the lower with the selector in place is because the cut out in the lower for the trigger is not long enough.