I’ve noticed a minor issue on my last few builds and I was looking for some feedback. My question pertains to how the trigger / hammer pins fit into the lower. In a perfect world I like the trigger pins to fit in the receiver with no wiggle room, but not so tight that they have to be tapped in. Seems like .154 pins fit kinda loose in some of my lowers, and they move around in the holes as a result. Is this anything to worry about? I guess my only concern is that this will prematurely wear or oblong the holes. I put oversize pins in a few of my builds and they fit much better, but I’m wondering if I should just stick with the standard size and not worry about it. Some of the lowers will accept a .156 pin and a couple of my PSA’s actually will take a .157. .154 pins in the PSA lowers bounce around quite a bit.
Who’s lowers and who’s pins? How are you obtaining measurements? One would have to make the assumption that the fire control parts are also out of spec if your able to use a 0.157 pin. If the pins are not behaving badly when the weapon is fired, I’d guess you have nothing to worry about.
The drawing shows the hole to be .1560" to .1575", after anodizing the hole should be .1550" to .1565" (The anodizing coating is .0010" thick, with hard coat anodizing, half the coating thickness is surface growth, half is penetration, so all surfaces grow .0005".)
For a “close slip fit”, a pin/hole mating that allows for the pin you be easily slid or rotated in a hole, you should have the hole about .0010" to .0020" larger than the pin, in the 1/8" to 5/32" range.
As to “wiggle”…
It can change the trigger feel, and if it get bad enough cause functioning problems (doubles, if the hammer pin moves too far away from the trigger). For the really loose receiver, I would: get an anti-rotation pin kit, and make it the over-size pin type.
And as an aside, unless you have worn pin holes, don’t use oversized pins. The hammer pin needs to have that .0010" to .0020" clearance, as it rotates with the hammer, the gap should hold a light coat of lubricant (grease).
As stated above, I would stick with the standard pins as there’s supposed to be “some” movement to them. But if it worries you too much, why not try out a set of KNS pins? I’ve been using them on my 80% builds (the .154" model) purely for added security. For an extra $23 versus the standard pins, I still feel like they’re worth it.
Thanks for the replies. I"ll probably just switch back to standard pins and call it a day. I’ll have to take a closer look at my two PSA lowers because they seem to be on the large side for the pin holes. Might try the oversize KNS on those.
the tighter pins do seem to feel more consistent and crisp.
I use the smallest possible oversize whenever I can detect the pin shifting around. geissele .155 then kns .1555 and one with .156. I find the .157 pins have a hard time fitting through trigger parts. Consider drilling to .170 if bad enough
big deal about tapping pins out, you have to give the standard hammer pin a tap anyway?
I wouldnt be surprised if they are on the loose side to ensure parts compatability.
Really? I have to believe this is a really bad idea.
Aren’t the pins captured by the springs?
Yes, the hammer pin is held by a spring inside the hammer, the trigger spring is held in place by the legs of the hammer spring.
Since the hammer pin is captured by a spring that is part of the hammer, that pin rotates with the hammer.