When it was first put together the trigger pull was in the 8-9 pound range. I wet sanded/polished the sear contact points on both the trigger and hammer to a mirror finish with 2000 grit sandpaper. That helped a lot, and I have the number documented somewhere, but I think it lost about a pound at that time. So, we’ll say it was then down to the 7-8 pound range. I had ordered a “field repair kit” from Aero Precision ( AR15/M4E1 Field Repair Kit | Aero Precision (aeroprecisionusa.com) ) that included both trigger and hammer springs. Since I didn’t have to remove the grip, safety, etc. I replaced the original hammer spring with the Aero Precision spring - lost another 1/2 pound and got to a consistent 6-1/2 pound trigger pull. That was over a year ago.
I’ve been toying with the idea of changing to one of the $100+ triggers, to the point I’ve been watching sales and hemming and hauling about it. So, this morning I thought why not try changing out the trigger spring before laying out future ammo procurement money replacing something that does work. First I removed the hammer and tested the original trigger spring - 1-1/2 to 1-3/4 pounds. I thought, that’s not much. Not expecting much for the effort, I pushed on and replaced the trigger spring with the Aero Precision field kit one. It was immediately obvious this was way less than the original. The gauge I use for pull testing confirmed it, definitely less than a half a pound! I should explain I use a Shimano 50 pound spring fish scale so measurements are not calibrated, but a relative change is a change.
With hammer reinstalled and upper back in place, the final pull is a consistent 5 pounds It does not have the same “feel” as the 5 pound pull on my 1911, but I am going to be happy with it for now.
To piggyback on what @USCCA said regarding modifying any firearm trigger- if you don’t have a full understanding of what you are doing, don’t do it!
Even though all I did was change one spring, I thoroughly tested the trigger operation after reassembly with particular attention to proper function of the disconnector. If you don’t know what I am talking about, you should not be working on your trigger.
I am embarrassed to admit it, but I’ve learned most of what I know about firearm trigger operation from the internet.
I hope this next comment doesn’t make me sound boastful, because it is not meant to be, but I also have decades of engineering design experience on mission critical projects where failure was not an option.
I sanded down a couple of triggers. Eh.
Then I bought a timney.
Then I bought a Geissel.
After market triggers are an order of magnitude better in my experience.
I prefer the Geissel over the Timney if I had to pick, but I will always swap out a OEM trigger for one of these.
Great question. The Timney has the potential to work loose (the set screws), making the gun inoperable.
Could it happen? I highly doubt it, but a very competent gunsmith who is also a competitive shooter walked me through this and convinced me.
The Geissel is a ‘standard’ type of spring trigger, and I think it’s at least equal, maybe better in the smoothness category.
I’ve got two Timneys in ‘hunting’ platform ARs, but my shooters are Geissel. Knowing what I know now, and after having shot both, I’d stick with the Geissel.
EDIT: just lost them all in a boating accident. Argh.
The truth of the matter is that “springs” can be played with to some good effect but the AR platform is not an M1 Garand or M-14 or M1A so stoning surfaces only gets you so far and swapping springs will only buy you so much. The simple reality is if you want a no kidding for real trigger you need a canned unit that drops in and is held in place by the two trigger pins. I have finger pooched more AR’s and M16’s than I care to remember and the truth is they are just not set up to be MATCH triggers in the original context.
To get a true 3.2# (or better) trigger you might be able bend springs and such but after 1K rounds it will be off. I don’t particularly LIKE my rat guns to have a match trigger but I can make them work.If it’s the only one you own then by all means go for the gusto but in general I can make mine respectable for the cost of a spring pack and a bit of time on the stone. Do remember that MOST AR parts have VERY thin heat treating and a fantastic trigger job can go away in a few hundred rounds if you break through. Only YOU can decide at what point you are going to pay for the boxed trigger or deal with 5+ lbs and such. The nice part is triggers swap with two pins if you have that need.
Revisiting an old thread today because Palmetto State Armory (PSA) tempted me with their 4th of July sale. Everyone that has ever shot my gun says the same thing, your trigger sucks!
A CMC 3.5 lb straight bow trigger made it to my front door today. Took the old polished up “Mil-Spec” out and dropped in the new one. I have to admit dry firing is like day and night difference. I can’t imagine what one of the super expensive ones must be like, but I am a happy camper with this one.
It is so hot here in Florida that it is probably going to be a few months before I take this out to the range for live fire evaluation.