• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

Take down and Pivot pins won't move freely






flintlock

Obsessed Member
#1
Just finished building my first AR 15 lower. I bought YHM-7284 pins because of the knob on the end that would make them easier to grab and move. The pins move freely in the holes, but with the detents and springs installed, they keep locking up. When I try and move them either way. Anyone have an idea why this is happening and what a fix would be?
Thank You, in advance.
 
#2
What do you mean by "locking up"?

Would think that if they didn't require at least nominal force to move, that they would back out or come out under regular function when firing the gun.

Are they still pullable without tools?

I once had a Colt Sporter AR, that the front pin was so sloppy loose, that it would back out every time I fired the gun.

Never got around to replacing it, just sold the rifle.
 

Janizary

Geth Prime
Forum Supporter
2019 Supporter
2020 Supporter
#3
If you mean they get 'stuck' at both ends, that is fairly normal with those YHM extended pins when fresh. Put a little CLP in the groove and 'pop' them out of the ends. Work them back and forth several times. That will loosen them up quickly, but still 'set' at the ends of their travel. I use those pins on all my builds and they lock pretty firm at both ends of travel when new.

If that is not it, just ignore my random blathering :)
 

flintlock

Obsessed Member
#4
What do you mean by "locking up"?

Would think that if they didn't require at least nominal force to move, that they would back out or come out under regular function when firing the gun.

Are they still pullable without tools?

I once had a Colt Sporter AR, that the front pin was so sloppy loose, that it would back out every time I fired the gun.

Never got around to replacing it, just sold the rifle.
They are definitely stuck and I have to use force wheather moving them in or out. It is like the detents become locked in the holes in the pins.
 

flintlock

Obsessed Member
#5
If you mean they get 'stuck' at both ends, that is fairly normal with those YHM extended pins when fresh. Put a little CLP in the groove and 'pop' them out of the ends. Work them back and forth several times. That will loosen them up quickly, but still 'set' at the ends of their travel. I use those pins on all my builds and they lock pretty firm at both ends of travel when new.

If that is not it, just ignore my random blathering :)
Thank You. I suspected that might be it. I will try to work them loose.
 

tdyoung58

Well-known member
Forum Supporter
2019 Supporter
2020 Supporter
#6
I use those to, they are a PITA when first installed, the will loosen up after about 100 or so times of using them.
 

DeanD

Summerlin
Forum Supporter
2019 Supporter
#7
Remove the small detent pins and stone the sharp tip off a bit. If you don't have a stone use wet-dry paper. Not a large amount just a bit of a radius instead of the sharp point. What you are experiencing is normal as the pins have a detent hole of sorts at each end to lock in place and the sharp tip hangs up, but like tdyoung58 said they tend to wear in. I always radius off the tip a tad and they work a lot better with just finger pressure.
 

flintlock

Obsessed Member
#9
Remove the small detent pins and stone the sharp tip off a bit. If you don't have a stone use wet-dry paper. Not a large amount just a bit of a radius instead of the sharp point. What you are experiencing is normal as the pins have a detent hole of sorts at each end to lock in place and the sharp tip hangs up, but like tdyoung58 said they tend to wear in. I always radius off the tip a tad and they work a lot better with just finger pressure.
Sounds like a plan. I will try/do all suggestions.
 
#10
Remove the small detent pins and stone the sharp tip off a bit. If you don't have a stone use wet-dry paper. Not a large amount just a bit of a radius instead of the sharp point. What you are experiencing is normal as the pins have a detent hole of sorts at each end to lock in place and the sharp tip hangs up, but like tdyoung58 said they tend to wear in. I always radius off the tip a tad and they work a lot better with just finger pressure.
I prefer do this also, it works great..
 

STV_Keith

Obsessed Member
#12
Remove the small detent pins and stone the sharp tip off a bit. If you don't have a stone use wet-dry paper. Not a large amount just a bit of a radius instead of the sharp point. What you are experiencing is normal as the pins have a detent hole of sorts at each end to lock in place and the sharp tip hangs up, but like tdyoung58 said they tend to wear in. I always radius off the tip a tad and they work a lot better with just finger pressure.
Yup, I take the pins to the grinder and round the ends. I also cut the springs down a bit...they don't need all that force. For the pivot pin, I cut the spring so about 3 coils hang out when the spring is fully in the hole. For the take down, I want to say I cut them almost in half...but it's been a minute...could be wrong there. Just use common sense.
 

flintlock

Obsessed Member
#13
Yup, I take the pins to the grinder and round the ends. I also cut the springs down a bit...they don't need all that force. For the pivot pin, I cut the spring so about 3 coils hang out when the spring is fully in the hole. For the take down, I want to say I cut them almost in half...but it's been a minute...could be wrong there. Just use common sense.
Thank You Keith. I need to get at this. I hate something that is unfinished. The take down spring was cut down so I could install a 4-40 screw. But it still sticks.
 

DeanD

Summerlin
Forum Supporter
2019 Supporter
#14
I suspect you may be looking to have them too loose and they aren't supposed to be loose per se. They should require a pretty good push with the thumb to unlock when engaged, other wise they may back out when firing or if they get bumped. I have had some that required using a punch, bullet tip, or other improvised tool to knock out when new but they loosen up over time. Just shoot it :)

I just noticed you are using the YHM pull pins. I think that was the first mistake and the problem. Put mil-spec pins in it and throw those away, just my opinion. I personally wouldn't want pins protruding out from my receiver.
 
#15
I use a pin vise to hold them and stone the point off, I also do it to the safety detent. I also use the pin vise to hold my Tungsten for my TIG torch when I sharpen it at the grinder, it helps to prevent burned fingers.

eQ