Had an old style rra. The top of the hammer would bind on the carrier. It ended up turning into a cruddy single stage.
RRA took it back and replaced it with a newer NM trigger. It wouldnt Work in my FAR 308, or two of my 5.56 lowers. They said it might be interference with non spec selector levers but u could send it back. I removed the selectors from all 3 lowers. Still didnt Work in the 308. (wouldnt release hammer) and worked with about a 20lb trigger pull in the 5.56 lowers.
3Rd trigger showed up. Still doesnt Work in the 308. I think the tail is too fat, or the front is hitting the pocket. It does Work in the 5.56 lower, but feels the exact same as my milspec trigger. It said 2 stage on the bag...but there is no "shelf" to indicate a second stage like other 2 stages ive used (to include the original first gen RRA). i dont really care at this point. I left it in one of the 5.56 guns and maybe something will change after some use.
Either way, im not sending it back, or ever trying another one. Not worth the irritation. Others have been happy with them.