View Full Version : Q about using oversized (.1555) pins
On my current AR, which was built before I knew as much as I should have, I used a RRA 2 stage trigger paired with a set of KNS 0.155 anti-rotation pins. I used the 0.155 instead of the 0.154 because I read the factory pins that came with the RRA 2 stage trigger were 0.155. Now that I know more, I am considering upgrading to a better trigger (probably Geissele) and I've read that Geissele does not recommend using the KNS pins. If I switch to their pins will it cause a problem after my receiver using oversized pins for a couple of years? I wasn't sure if the holes could be slightly stretched from the bigger pins and would now not hold regular, non-captured pins. Should I just stick with the KNS pins on this build and learn my lesson for future builds?
Correction... Apparently, the KNS oversized pins are 0.1555. Doesn't seem like enough to make a difference but I wanted to see what you guys think.
vicious_cb
06-03-12, 17:39
No, use the geissele pins. They are precision ground and much much higher quality than KNS pins.
No, use the geissele pins. They are precision ground and much much higher quality than KNS pins.
I understand they are better pins. I'm not arguing that. What I'm asking is if using the 0.155 pins has enlarged the hole and will cause issues if I switch to the Geissele pins.
vicious_cb
06-03-12, 18:16
No it wont enlarge the hole, unless it was out of spec in the first place. What causes enlarging of the firing pin holes is repeated removing the fire control group.
Well since you didn't tell us what kind of lower you have let me say this. I don't know where you got .154 from. But the milspec is not .154 it is .155.
Well since you didn't tell us what kind of lower you have let me say this. I don't know where you got .154 from. But the milspec is not .154 it is .155.
The lower receiver in question is a CMMG. The reason I assumed a standard pin was 0.154 was that KNS lists their standard pin set as 0.154 and their set for tightening up 2 stage triggers or for receivers that are already loose as 0.155. I assumed from that info that the 0.155 pins were very slightly oversized. If I was wrong, that is great. I can just pull the KNS pins when I get the Geissele trigger and not have to worry.
IIRC Geiselle's pins are .155 so there should not be any issues.
Mark
Correction... Apparently, the KNS oversized pins are 0.1555. Doesn't seem like enough to make a difference but I wanted to see what you guys think.
Most manufacturers make their lowers with the .155 holes. So you shouldn't have any issues at all. I would dump the KNS pins as they serve no useful purpose.
The lower receiver in question is a CMMG. The reason I assumed a standard pin was 0.154 was that KNS lists their standard pin set as 0.154 and their set for tightening up 2 stage triggers or for receivers that are already loose as 0.155. I assumed from that info that the 0.155 pins were very slightly oversized. If I was wrong, that is great. I can just pull the KNS pins when I get the Geissele trigger and not have to worry.
Most manufacturers make their lowers with the .155 holes. So you shouldn't have any issues at all. I would dump the KNS pins as they serve no useful purpose.
I have now learned that the KNS pins are 0.1555. Does that change your answer?
I have now learned that the KNS pins are 0.1555. Does that change your answer?
NO it won't :)you need to get to Know IG .what he says he means he Knows his weapons and how and what to use to set it up right
NO it won't :)you need to get to Know IG .what he says he means he Knows his weapons and how and what to use to set it up right
I am not doubting his knowledge at all. He seems to really know his stuff. However, when he and I started this exchange I had bad data. I thought the KNS pins I had installed were 0.155 which he taught me was the same size as the holes in my receiver. Now, I know that the KNS pins are actually 0.1555 so with that added knowledge, I'd like to know if it changes his opinion on if it is safe to go back to standard pins.
They aren't needed so use the ones that Geissele provides and and that's it.
I am not doubting his knowledge at all. He seems to really know his stuff. However, when he and I started this exchange I had bad data. I thought the KNS pins I had installed were 0.155 which he taught me was the same size as the holes in my receiver. Now, I know that the KNS pins are actually 0.1555 so with that added knowledge, I'd like to know if it changes his opinion on if it is safe to go back to standard pins.
GTG Frogger:D IG has Helped and schooled me on things many times .he is a Member i have found to be the Go to guy for questions .i didn't mean to come across in a negative way if it sounded that way
GTG Frogger:D IG has Helped and schooled me on things many times .he is a Member i have found to be the Go to guy for questions .i didn't mean to come across in a negative way if it sounded that way
You didn't. I just wanted to be clear that I wasn't questioning his expertise. I just wanted clarification that the change in pin size didn't change his answer. Sounds like I can just toss the KNS pins in the parts bin when I get the Geissele and not worry about it. I'm glad to hear it because I'm building a 2nd AR that will be pretty much a clone of my current one and this saves me the money I would have spent on the KNS pins on that one. :D
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