Trigger pin size??

[crat0837]

I received my RRA 2-stage match trigger in the mail today and noticed that it comes with 'oversized' trigger and hammer pins (.156"). I will be installing this on a new build/lower which will have tight trigger and hammer pin holes still. I tried seeing how easily the pins fit and they seem REALLY tight. I am looking at getting some KNS anti-rotating pins to replace the ones in the kit but am wondering if I should get the standard size instead of the oversized. First, should I get the oversized, since that is what the RRA kit calls for? And second, any suggestions on how to get the pins in without breaking something because of the tight fit?

Thanks!!

[mvician]

get the standard .154" pins

Don't pound the oversized pins into your lower, oversized pins are for worn lowers. The holes wear as the pins rotate in them, the KNS pins stop the rotation and prevent the "walk" from side to side.

[crat0837]

Somehow I knew you'd be the first responder.ha ha

Anyways, so the trigger kit assumes that it is replacing a trigger in a worn assembly? The holes through the actual trigger and hammer wont be affected by the smaller holes?

[ThumperMX113]

+1.

[mvician]

Originally Posted by crat0837

Somehow I knew you'd be the first responder.ha ha

Anyways, so the trigger kit assumes that it is replacing a trigger in a worn assembly? The holes through the actual trigger and hammer wont be affected by the smaller holes?

I'll admit I have no experience with the RRA 2 stage.....but I do with the KAC 2 stage. The KAC 2 stage uses the normal .154" pins and on one of my setups I used the KNS .154" pins.

If I was putting together a new lower with the RRA trigger I guess I would see how tight the oversized pins were...........hopefully someone that has installed the RRA will be able to tell you how their install went.

[Wild Rice]

The (very slightly) oversize hammer pin and trigger pin that come with the RRA NM trigger kit are designed to eliminate play and improve the trigger action. I recommend that you install all the supplied parts in the kit. I have RRA NM triggers on all (4) of my AR's and it is a great two stage trigger system. If you are concerned that the pins will be too big for your receiver, you can test the pins fit in the stripped lower receiver holes. They should fit with less play that standard pins, but should not require undo force to insert into a stripped lower receiver (no hammer, trigger, or springs). It is rare, but sometimes the hole in the hammer or trigger may have to be very slightly widened or deburred to prevent binding on a NM pin. You should never intentionally widen receiver hole as it could alter the spacial relationship of the fire control system and ruin the lower receiver beyond repair.

You are more likely to enlarge the receiver pin holes by using an improper punch or forcing a pin when the parts are not lined up. Firing full auto and firing a 9mm conversion is also supposedly hard on the hammer pin/hammer pin hole.

Make sure you test the trigger/safety per the RRA instructions. Do not allow the hammer to go forward with full force when the upper and lower are apart. That can damage the lower receiver and/or bolt catch. The instructions were not too clear about avoiding that.

Hammer pin walk is best prevented by having a strong J wire in the hammer. I had a Stag hammer with a loose J wire that caused hammer pin walk. I fixed it with a RRA hammer. All (5) of the RRA hammers I have checked have stout J wires with excellent hammer pin retention. A slightly OS pin can still walk if the J wire is bad. As long as my AR's have a good J wire, I do not feel the need for external anti-walk anti-rotation systems for firing semi-auto .223. It is one of the weak points of the AR design that some remedy with the KNS system.

[ThumperMX113]

Are the triggers that come with the RRA 2-Stage really the oversized pins? I tried to measure them but didn't have anything precise enough.

[Wild Rice]

Yes, the RRA NM two stage trigger kit will come with slightly oversize NM pins for the hammer and trigger. It helps eliminate play in the trigger action for less creep and a more crisp release. You can order RRA hammer/trigger pins directly from RRA and there are two different part numbers for the regular pins and NM pins. The easiest way to check is to insert the pin part way into a spare hammer (without engaging the J wire) and wiggle the pin in the hammer hole. Both pins will fit, but a NM pin will have slightly less play when wiggled.

KNS sells stainless steel oversize small pins (0.1555) that would be easy to visually distinguish from blued or parkerized stock pins and the SS might wear better as there is no surface finish. "Oversize small" is an oxymoron because Colt uses large (0.170) pins on some of their AR's.

[darkvibe]

edit: nevermind.

[crat0837]

Originally Posted by ThumperMX113

Are the triggers that come with the RRA 2-Stage really the oversized pins? I tried to measure them but didn't have anything precise enough.

Yes, it is specified in the directions that they are the oversized pins which will measure .1555". The standard size is .1554". It is a pretty tight fit, I tried (not too hard) to see the fit in both my unused stripped lower and also in the trigger itself and they were both pretty tight, hence my asking which size KNS anti-rotation pins I should get. Maybe I'll call the RRA tech # and ask them