Rise Armament RA 140 trigger and Aero Precision lower

ks_wayward_son · February 27, 2018, 07:24 PM

Hey all. I've researched a few instances when Rise Armament drop in triggers would not fit in Aero lowers. Im sort of concerned because I am getting an Aero upper and already have a Rise 140 trigger, and I would like to get the Aero lower for better fitment...plus I've heard the Aero uppers and lowers are just well made.

Can anyone verify or nullify this information? Had good results with installation without modifying the lower?

Thanks.

DW

imashooter · February 27, 2018, 08:05 PM

I can't think of too many ways where it wont fit / function. I had that issue installing one in an Oracle. The deal was it fit just fine however, the upper front corners were just kissing the forward-most area of the inside of the receiver. This was causing the trigger to not reset. The remedy was easy. I filed away, (mostly dremeled) the upper sides / corners of the cassette body. Probably 1-1.5mm material removed. Another guy in another forum knew exactly what the issue was and he nailed it. Said the Oracle was not of perfect spec. Here is what I can provide:

"Here is a rough drawing, but the shaded areas need to be worked with a flat file."

"The 135degree angle interferes with the front of the trigger pocket. Just round the angle till you can fit both kns pins freely. Be careful not to get into the hollow pin that holds the hammer in. If you do you are filing to far back."

"... the angle just forward of the hammer pin sleeve. My "picture is looking down from the top of assembly."

Me: "Just radius the forward - upper sides and the angled cuts on the very front upper of the module."

Response to me: " Just radius the forward - upper sides and the angled cuts on the very front upper of the module."

Me: " I filed away what I'm pretty sure was the correct area. Took it as far as I could without hitting the hammer pin insert/sleeve inside the module. Finished it with a fine cratex bullet in the dremel (I hand filed). Glad that housing is aluminum. I first tested with factory pins and safety installed. The trigger pin had resistance but I was able to push it in with fingers only. Same deal with hammer pin but it's resistance was "smooth" if that makes any sense.

Performed function check with fully assembled weapon. It did well. Reset each time followed by me successfully pulling/firing the trigger . Installed KNS pins, tested, same results. So far so good I reckon. Safety works and all that. Though I requested RA send my new trigger with the set screws loose in the pkg, the screws were installed (kind of glad actually) but remained recessed, not protruding as they did on the other trigger. I have one 5/64th hex left. 7.00 one at that. Talked with RA for clarification and they told me to install the KNS pins followed by adjusting the set screws. Gonna take me a little break and attack those damn screws. Sure hope they turn this time and the resistance when bottoming out is discernible or I'll be a little bit PO'd. Hope to fire it tomorrow. Let me now go F with those screws."

It worked perfectly. If this is your problem and all the above is "sketchy" (lol), give a holler and I'll try to do better. Good luck.

February 27, 2018, 07:24 PM	#1
ks_wayward_son Senior Member Join Date: July 19, 2007 Posts: 332	Rise Armament RA 140 trigger and Aero Precision lower Hey all. I've researched a few instances when Rise Armament drop in triggers would not fit in Aero lowers. Im sort of concerned because I am getting an Aero upper and already have a Rise 140 trigger, and I would like to get the Aero lower for better fitment...plus I've heard the Aero uppers and lowers are just well made. Can anyone verify or nullify this information? Had good results with installation without modifying the lower? Thanks. DW

February 27, 2018, 08:05 PM	#2
imashooter Senior Member Join Date: December 28, 2013 Location: Alabama Posts: 395	I can't think of too many ways where it wont fit / function. I had that issue installing one in an Oracle. The deal was it fit just fine however, the upper front corners were just kissing the forward-most area of the inside of the receiver. This was causing the trigger to not reset. The remedy was easy. I filed away, (mostly dremeled) the upper sides / corners of the cassette body. Probably 1-1.5mm material removed. Another guy in another forum knew exactly what the issue was and he nailed it. Said the Oracle was not of perfect spec. Here is what I can provide: "Here is a rough drawing, but the shaded areas need to be worked with a flat file." "The 135degree angle interferes with the front of the trigger pocket. Just round the angle till you can fit both kns pins freely. Be careful not to get into the hollow pin that holds the hammer in. If you do you are filing to far back." "... the angle just forward of the hammer pin sleeve. My "picture is looking down from the top of assembly." Me: "Just radius the forward - upper sides and the angled cuts on the very front upper of the module." Response to me: " Just radius the forward - upper sides and the angled cuts on the very front upper of the module." Me: " I filed away what I'm pretty sure was the correct area. Took it as far as I could without hitting the hammer pin insert/sleeve inside the module. Finished it with a fine cratex bullet in the dremel (I hand filed). Glad that housing is aluminum. I first tested with factory pins and safety installed. The trigger pin had resistance but I was able to push it in with fingers only. Same deal with hammer pin but it's resistance was "smooth" if that makes any sense. Performed function check with fully assembled weapon. It did well. Reset each time followed by me successfully pulling/firing the trigger . Installed KNS pins, tested, same results. So far so good I reckon. Safety works and all that. Though I requested RA send my new trigger with the set screws loose in the pkg, the screws were installed (kind of glad actually) but remained recessed, not protruding as they did on the other trigger. I have one 5/64th hex left. 7.00 one at that. Talked with RA for clarification and they told me to install the KNS pins followed by adjusting the set screws. Gonna take me a little break and attack those damn screws. Sure hope they turn this time and the resistance when bottoming out is discernible or I'll be a little bit PO'd. Hope to fire it tomorrow. Let me now go F with those screws." It worked perfectly. If this is your problem and all the above is "sketchy" (lol), give a holler and I'll try to do better. Good luck.