I saved for many years and finally got to buy a legally registered full auto M16 lower.  It is just the bare bones lower receiver with nothing in it so I need to buy everything else.  I am not experienced on M16 parts so bare with me as I try to learn from you guys.  I have heard most M16 triggers are just 3 Position ; Safe, Semi, and Full but that there are a few 4 Position Selectors with a 3 round burst mode.  That seams like it would be nice to have the ability to fire both a 3 round burst and Full-Auto, but I am concerned about reliability and trigger pull weight.  

Questions :

1.  How many different companies make a 4 Position Selector and who are they ?

2.  Are the 4 Position Selectors just as reliable as a regular 3 Position ?  

3.  Do the 4 Position Selectors have a heavier trigger pull ?  I had a bad surgery on my trigger finger so a heavy trigger pull will always be a problem for me.  

4.  What are the Pros and Cons of a 4 Position Selector trigger vs a regular 3 Position ?

5.  If you guys recommend a 3 Position over a 4 Position, who makes good light trigger pull weight 3 Position M16 Full-Auto triggers ?  

6.  Are there any 3 Position Selectors with a very short reset that I could learn to do 3 round bursts on Full-Auto ?  Preferably not a two stage.  

Thanks in advance for any helpful replies

https://geissele.com/super-select-fire-ssfr-trigger.html


get this.

I would just stick with a 3 stage with FA.  Personally I don't think 4 stage doesn't really give you any benefit.
M16A2 are burst which was done to not have the GI waste ammo..

As for people's comments about the Geissele SSF.. GET IT. That is a remarkable trigger.  Love mine. Of course I'm a big Geissele fan since I have probably 6 other ARs having the various triggers (SSF, SSA-E, DMR, S3G, etc)

Other item I would get is the Surefire OBC. It was designed by Leroy "James Sullivan.. One of the designers of the AR15. You can shoot it using one hand which is amazing.  I'm trying to get my hands on one!

The only times I've found burst or 4-pos useful are on platforms with very high cyclic rates - like 22LR or certain 9mm setups. In rifle calibers, I have no problem doing 2 or 3 round bursts from a 3-pos FA trigger with just trigger control.

In FA, a 4-pos will have a slightly heavier trigger pull than a 3-pos, because you're compressing two disconnector springs instead of one (regular FA) or none (semi).

The two makers of 4-pos sets I'm aware of are Colt and DPMS/Tapco, and their selector positions are different.

This is true.  I have both a 3 round burst 3 pos and full auto 3 pos and doing bursts with the auto is fairly simple with a little practice.

That said, the 3 round burst really is fun, I like it more than most people.

I don't have any personal experience with a burst fire M16, but when this question comes up, probably the most common response is this:


Best of luck and enjoy whatever you pursue.
MHO, YMMV, etc.  Be well.

I have to agree.
Well, no, I don't really have to, but I choose to.

With a little bit of trigger time it's no challenge to get 2 or 3 round bursts from a standard FA trigger set. If you really practice, sometimes you can even (almost reliably) get single rounds while in FA.

The annoying kicker with burst - It works like a ceiling fan. It does it's thing in the order and in the number it's designed to, then pauses. Period.

If you only hold the trigger down long enough to get two shots of the burst, the next time you hold down the trigger you get the remaining shot then a pause. For folks with no trigger discipline it's great, because you'll get a 3 round burst every time you hold the trigger back. For folks who give light, quick presses, you often stop before the pause, making your next "burst" a single shot.

This^^^^^^

Did this with my full auto and switched it out about a month later. Now the four position just sits in the drawer and as most have suggested I now have the SSF Geissele in it.

Skip the 3rb. As others have said, just buy a Geissele SSF. Second runner up is the LMT 2-stage FA fcg.

The Geissele trigger is a great trigger for a M16. Yo are  looking at $400 for it. There is another option. J.P. Enterprises  https://www.jprifles.com/1.4.8_fc.php makes an adjustable single stage. The least expensive option is around $100 retail. Whether in auto or semi the trigger is single stage. It used to be open in the back, but the most recent purchase of this trigger, the back of the trigger was boxed in like a semi automatic trigger. The trigger does require adjustment to the a specific lower. The adjustment also limits over travel. With their springs you can have a 3 lb trigger pull.

There is also the "amphibian" buffer setup. The Tubbs flat wire spring and the Vltor A5/.308 buffer tube. That will slow the cyclic rate of even short barrels to a point where pulling single rounds with the selector in the auto position. If you want to try a 3-round burst trigger, it is much cheaper just to buy one than buying a four position system.

Congratulations on the purchase of your M16 RR. There are some choices out there for you for triggers. Good luck putting your lower together.

Scott

ETA Knights Armaments Corporation also makes a drop in type of trigger similar to the Geissele trigger for the M16.

Getting bursts of 3 is relatively easy.
It just takes a little practice

Geissele or KAC?

FPNI.

SSF is the way to go.

Reliably pulling off 2 or 3 rounds bursts is easy with a bit of practice with the trigger.

Love my Geissele SSF.

+1

I only have a couple of burst trigger groups for my HKs (mainly because they look cool), but I prefer 3-position auto.

Right on, thanks.

Here's another 4 position trigger in an assembled pack.  

https://www.ptrdd.com/product-page/4-position-fire-control-group

I don't know much about them other than they make them.