I have a (legally) converted AR with a 2-position FCG - SAFE/AUTO.

Besides the selector, what parts do I need to swap to get 3-position SAFE/SEMI/AUTO?

Or should I swap the whole FCG with an M16 FCG?  I see many for sale, but most don't mention if they are 2-position or 3-position.  Is it correct to assume that they are mostly 3-position?
- Dave

How is your AR converted? If it is a registered receiver using a GI autosear, or if it uses a drop in autosear, then it should use standard M16 FCG parts, which are 3 position. You could have an M16  hammer, no disconnector, and a semiautomatic safety, and that would give you safe/full auto with an M16 autosear and bolt carrier. If that is the case, then adding an M16 selector, trigger, and disconnector would give you selective fire.

If your AR is converted using a Lightning Link, then safe/auto is the standard setup using SP1 semiautomatic FCG and bolt carrier. There is a selective fire kit for Lightning Links that I invented (though another individual gets credit for my invention because I blabbed my mouth about it in his presence), using modified M16A2 FCG parts. John Norrell of Little Rock, AR is the original supplier of these kits. I am not sure if John still sells them.  John is good people IMHO. Good information about Lightning Links, and mostly correct information about the M16A2 fcg  based selective fire  RLL kit can be found here.

It would be really rare to have a registered receiver (with a factory autosear) with a 2 position Safe/Auto fire control group.  The only guns I am aware of that ever came with a Safe/Auto fire control group (along with the associated bolt carrier and buffer system) were the Bradley Port Firing Guns and would be extremely rare.

Most M16s are three position (Safe-Semi-Auto) or are a modified "burst" three position (Safe-Semi-Burst).   There are four position groups out there as well (safe-semi-burst-auto) and there are two different variation of this 4 position kit (DPMS and Colt Pattern).

If you need new fire control components I would just get a full set of Colt FCG from Ken Elmore at Specialized Armament Warehouse.

Now if you gun was converted via a Lightning Link that is a different story and you need to custom modify a 3rd burst kit that will result in Safe-Semi-Auto.   Its a pretty straight-forward process to convert a 3rd burst FCG to enable Safe-Semi-Auto with a lighting link.

If you can post some pictures of what you have it would be helpful to enable us to provide more clear advise on what you need to change out.

CT or one of those other messed-up northeastern states allowed machineguns, but not select-fire, hence there have been some SAFE-AUTO only setups, even for factory guns and properly-converted RRs.

Provided OP is not in that messed-up northeastern state, then replacing the 0-A is as easy as replacing the selector.

If it's an RLL, then it'd need the modified burst group, as mentioned.

Thanks for the notes.  I forgot to mention in my original message that this is a RR (converted AR) with an autosear - no LL or DIAS.

I don't know much about the history, so it could have come from one of the strange northeast states.

It sounds like my best bet is to replace the whole FCG.

Will send pictures to confirm before I proceed.
- Dave

I recommend a Geissele SSF trigger group with an M16 selector.