Rig unloaded, selector on full auto, and trigger taped back.

Pull the charging handle all the way back, then ride the charging handle forward which sticking in the back end of a drill bit between the front of the carrier and back of the barrel extension to use as a feeler gauge of when the auto sear releases the hammer.

Correct gap for auto sear release of the hammer of the distance between the front of the carrier and back of the barrel extension  will be .083".  So your go and no go drill bit sizes are #45 as your go gauge with thickness of .082", while your No Go (auto sear not releasing the hammer)  is a #44 at .086".

Next, suppressor will increase back pressure, so via a single round in the mag, load and fire the single round, and make sure that the bolt will lock back on the bolt catch (catch in front of the bolt, and not just under the carrier holding it back that way instead).
So depending on the amount of back pressure increase via the can, may need to adjust either the gas pulse, or just increase the mass of the buffer to slow the bolt lock down to get the correct rear cycle so the bolt is locking back correctly on the single round test.


Now on bolt bounce and correct auto sear release gap, the more you are out of the correct timing, the more a heaver buffer may help with bolt bounce.  Simply, Kity cat rigs that are mac Jacked to run at 1400rpms plus, so long as you have the auto sear timing correctly, don't need to run a heaver buffer to control bolt bounce.  Hence with correct auto sear timing, hammer is striking the FP and igniting the primer just a hair gap before carrier is touching the carrier on the way forward (before the carrier has time to strike the barrel extension and bounce back), still have the forward momentum of the B/C forward like on a Uzi to help absorb recoil, and again, long before the carrier has a chance to bounce back off the  barrel extension for the FP to be blocked back the back of the carrier.

As for all Colt and FN parts rigs, don't have problems with sear timing so much (short of  parts wear), but when you get into none USGI parts, (including just the barrel as well), most of the time you need to go in and time the rig correctly instead.  
As for what to rework, just depends on the differ set ups your running on the Registered sear lower.  
Some times is just the sear or hammer that have to be reworked, while if different upper combo's are all over the map that will be run on the lower, may have to start with the carrier bottom shelves to get them all into a constant spec, then go after the auto sear/hammer to fine tune all the different combo's into the correct release timing of .083" in the end.

If new round was stripped out of the mag, then hammer came back far enough for either the disco or auto sear to catch them in the first place.

The can will cause the bolt to unlock sooner, but this is more of a matter of if the B/C is full stroking in the first place or not (if bolt is being locked back after the last round out of the mag is fired by the bolt catch in front of the bolt).


As for bolt bounce between suppression or not (if B/C is coming back all the way to begin with),  still comes back to correct auto sear gap distance off the barrel extension being correct or not.   Yes, buffer with more mass may help to control carrier bounce back better, but if auto sear release gap is correct in the first place, FP is igniting the round while the carrier is still moving forward.  If the gap is too large, then hammer is striking the FP while the FP stop collar is still being blocked by the back of the carrier (FP can not achieve full bolt protrusion on the initial primer strike).