Retaining Pin Legs Bent Apart: I ran across the same issue on two AR 15 bolt carrier groups. The firing pin retainer AKA the cotter pin has the legs spread so far apart it's damn near impossible to put back in place once you pull it out during regular maintenance. The first of the two bent ones I was able to coax back in using needle nose pliers, but the second was an absolute "no go". I was about ready to head down to the LGS and get a new one when I ran across a YT video that shows how to fix the pin. It's so freaking simple once you know the "trick". Simply put something in the pin to spread it a bit further apart and squeeze the tips together with pliers. The goal is to leave a small gap so they apply some pressure and stay in place, In the video he uses a thumb tack, but I used a very small hex wrench. Here is the video. Audio is stupid low, but you can see how to do the fix: Reinstalling the Firing Pin Retainer Without Uttering a Single F Bomb: Many times it's hard or damn near impossible to get the retaining pin to go all the way through once you get it past the firing pin itself. In the past i've just applied more pressure and this may be how some pins got bent in teh first place. Like everything there is a trick. Orient the eye of the retaining pin so you can see through it when you look down at the bolt from the gas key side and push until you feel it against the far side of the bolt carrier. Now, using the eye like a handle, wiggle the retainer up and down until you feel it contact the hile. You can even see it from teh rear of the carrier or through the hole itself.
love the simple fixes, nothing beats "Why didn't I think of that!" Like simple little tool to put ball and spring retainer in on AR 15. With tool, seconds, without, where the He** did that ball go?" https://palmettostatearmory.com/battenfeld-pivot-pin-roll-pin-installation-tool-156243.html
You can get five of these for 8 bux on Amazon, Works jexactly the same way you just dont get the ring to help you turn it. Pops up on an Amazon search for "pivot pin tool" as well. I've also done the kraft knife trick, but these work way easier. https://www.amazon.com/dp/B01B5DBZAO/?tag=survivalmonke-20
All be Damned, that was a neato trick with the take down pin! I always used a slight cupped dental pick, it always worked, but I can see the cotter pin trick being way easier! Never had any issues with the firing pin retainer, might be because I leaned to twist the key as I pull it out, and pinch it a little as I re install it, IDK, but I have never broken one, or had one fall out, and I have done this more in one year then most have done in a life time!
That's why a small family place up the road sells "oops kits". $15 for all the #$%^& little bits that tend to disappear. I bought six of them for x-mass gifts last year.
The one I had to bend was spread wider than a.... well I guess I better not say other than close to 30 degrees! I even had to really FORCE on it to remove it, With pliers it kept rolling out of position. Half a minute after I watched the video it was perfect, slid straight in but with enough tension to hold it firmly in place. It was a new BCG that came with a new PSA pistol upper I bought from @GOG and has never been fired. i have a suspicion when it was installed one leg didn't line up and was bent downward, and when I FORCED it back out I straightened it a little. Good thing I decided to do an initial clean and lube before I test fired it - I'm not sure how well that bent portion would have worked with an actual round! Lesson there is always inspect anything new to you or that has been worked on by someone else!
I've done the knife blade thing in the past. but this tool makes it idjut pruf. Still have 4 extras if you want one or two.
One of life's greater pleasures is seeing a simple little trick that makes life much easier. I fought for an hour and ruined 2 of the end pieces and lost one spring on my first try. Now it takes a second and works every time. I am a sucker for AR tools and parts, so nice to have all the little parts handy when you ruin or lose one.
Full disclosure, I'm not an AR15 aficionado, but I do have a special relationship with the M16 firing pin retaining pin. I'm familiar with the M16, and the only trouble I ever had with the firing pin retaining pin was dropping one in the snow and losing it during a match at Quantico. I've installed them countless times, almost effortlessly, and often without looking. I wondered if the issue wasn't that the pins are somehow different, but looking at the retaining pin on my key ring, I see that that's not it. Think about it. Marine recruits can do complete disassembly and reassembly of an M16 in under 60 seconds, with no tools. I don't think anybody ever taught us to press down on one side or the other. Simply rotating the retaining pin slightly while applying pressure is all that's needed. If it's any harder than that your pin may need a little more bevel on the end. I've had a cotter pin on my key ring for almost 40 years. The one I happened to have with me that day at Quantico was just a little long, and left a scratch in the receiver, but it worked. I got a scratch somehow that day too, and by the time I left the 500 yard line I had left a red spot in the snow and had frozen blood all over my pistol grip. I shot a possible with 18X and won the long range competition, even after fumbling and losing my firing pin retaining pin in the snow at the 300 yard line bench.
Though some manufacturers at different times have made changed to the bolt carrier group to prevent full auto operation (like partial shrouding) the M16 and AR15 bolt carrier groups are identical. the BCG in my PSA discussed above was made by Toolcraft to the same specification as the ones they provide to the US military as M4/M16 replacements. Both legs of the retaining pin should be nearly parallel with just a slight spread to apply just enough pressure to hold it in place. I think what happens is that instead of lining the pin up correctly and only applying what should be gentle pressure that some people will apply excessive force which results in bending the pin before it goes into place. Obviously you should have spares of the retaining pin and other parts that get consumed or easily lost, but sometimes you just need to fix what you have.
