Guys - I've hit a wall with my full auto .22 conversion and could use some advice. My setup is as follows:

Sp-1 RR with CMMG stainless .22 FA conversion using their sear trip and anti-bounce weight. 4.5" CMMG .22 upper with and without suppressor.
The setup runs fine in semi, however I can never get more than 3-4 round burst in FA with a light rim strike on the last round and hammer down.

I've spent a lot of time going researching .22 full auto issues online. These are the tweaks I have tried:

High and hyper velocity ammo - CCI mini mags, Stingers, Remington Golden, Yellow jackets, ect
Several types of Black Dog and CMMG mags
TACCOM plug
Mil-spec and Geiselle SSF triggers
Lakeside recoil and trigger springs - trimmed recoil spring.
Fitted sear/hammer engagement.

Any help is appreciated.

Sounds like bolt bounce, you could try the ball detent mod in addition to the anti-bounce weight. Try searching ar conversion ball detent mod on goggle and it should pop up. Spikes kits used to have it standard.

Im assuming this is on a RR? You might have to bend the trip to ensure engagement or timing.
But
I would think a weaker hammer spring may help.

I like the tappcon firing pin and the thing you inserting into the buffer tube infront of the buffer weight helps the keep the drop in conversion where its supose to be.

Send me an email to [email protected] and I will send you a list of what I did to get mine running.

Mine runs great, it's a Ciener but it's still close enough to the CMMG. I installed the ball detent and no longer run the anti-bounce weight. Placed a couple o-rings in the barrel extension to hold the chamber adapter and played with a spacer between the buffer and the guide rail end cap but it never made any difference in my gun which is also a converted SP1.

You may need to tweak the sear trip as suggested by MGnoob, I cracked one and it never worked correctly after I welded it up. I bought some of the CMMG trips at Knob Creek an few years ago but haven't used them yet so I can't speak to their functionality.

Also check your FCG as worn parts create problems similar to those you're having with these 22 kits, again ask me how I know!