It comes up from time to time, so I thought we could "talk" about it for a bit.
We have two versions of our two-stage trigger. Both work equally well, although the parts are not interchangeable between them. That works out well, because we don't sell the NM trigger group parts separately. We build each set, as a complete set, in a lower before anything else happens to it. Surfaces are polished (maybe even filed at times), springs are set, weight is verified...then, if it is afor a lower half or complete rifle, that trigger stays right in that same lower to be built further, tested ,and shipped. If it is for a trigger kit or lower parts kit, it is taken out of the test lower, bagged and tagged, and sent to the Shipping Department.
That said, sometimes they look like they have a little wear on them...that's the fitting and testing. Every 2-stage trigger kit that goes out the door has already been tested in at least one lower. Fit, function, and pull weight are all verified.
Now the rub. Tolerances in lowers. All lowers have tolerance, even ours'. We try to use as close to the call out as possible for testing, to assure that they will work in the majority of lowers on the market. I say majority, because they won't work right out of the package in all lowers. we've tried multiple manufacturer's lowers, and most of them are very close to ours, and the trigger kits tend to drop in easily and function just fine. Some, however, are all over the place for the pin hole tolerances, both location in the lower and in diameter. For the proper trigger function, we're dealing in thousandths and ten thousandths of an inch. we've found lowers off by hundredths of an inch on location, and easily off by thousandths on both location and pin diameter. One of the reasons we use slightly over size pins. we can make them work in most lowers at that point, with no pin movement...just the trigger and hammer moving on the pins,,,they way it's supposed to be.
But we can't always make that happen in all lowers by all manufacturers.. There's nothing necessarily wrong with the trigger kit or the lower....but physics dictates that they don't play well with each other. If we have the lower, we can often make a trigger kit work in it. Without the lower, it's far more difficult because we don't know where the problem is. Sometimes that requires that a custome rhas to send in his lower and the trigger it he received for us to "fit" them. Most of the time, the only charge is the customer picking up the shipping. If it really is a warranty issue, we cut the customer a check for the ground shipment to us (or offer in-house credit), and pay to ship it back. We try not to do anything to the customer's lower, and accomplish everything via the trigger kit components.
Occasionally we do have legitimate problems with our triggers....some times fairly early in their "life" when an edge disappears, and sometimes tens of thousands of rounds later after they are just plain worn out. We take each on a case by case basis as far as repairs go. we're just introducing a new maintenance offering where we replace the springs in a trigger kit and touch up any surfaces that need it for a flat rate...not for the new sets, but the ones that have been out there for awhile ands have maybe dropped a little weight and are starting to "feel" different. We don't require them in the lower that they're being used in, but it sure makes it a lot better for everyone when they do.
Early on (a decade or more ago) we had some hammers break, and occasionally still do. In the old days, it was generally due to occlusions in the metal. We stopped that by magnafluxing and performing other tests on every hammer and purging any that were remotely questionable. The more recent breakage is more often than not associated with test firing by the end-user with the upper removed and letting the hammer go forward and impact the back of the magwell or bolt stop. Sometimes it's accidental, and sometimes it's intentional (nothing bad will happen,,.,this guy on the internet said so). Either is few and far between, but they tend to get blown out of proportion on line when they do happen. I'm still seeing photos from 12 years ago being passed off as "look what happened to a buddy's buddy's RRA hammer this weekend". We have the original photos from way back when. We know the guy who posted them before sending in his lower. He regrets ever posting them We fixed his trigger group and had it back out to him in less than a day. He's bought more triggers, lowers, and rifles from us since, but his photos are immortal.
I didn't want this to turn into a rant, and I hope it doesn't come off that way.
if you want/need more two-stage trigger info, this is the semi-official thread to ask or comment and I'll try to provide an answer/solution. Let's talk about those RRA 2-satge triggers in this thread and see if we can answer the questions and help one another out.
Thanks.
Steve/RRA