The suppressor increases the bore back pressure after the bullet has passed the gas port (just think of the barrel being longer after the gas port), which  increases the amount of gas to the gas system to unlock the bolt, which in turn opens the action a tad bit earlier than needed.

Just increasing the mass of the buffer slows the action back down to open at the correct time with a suppressed rig.

Barrel does not mean shit, as well as any other thing on the upper receiver when you are talking Buffers!!!

We need to know the length of the receiver extension on the lower receiver, hence is it a telestocking stock, or a fix full length stock instead (depth of the tube inner void).   This will tell use if your rig used a carbine buffer or standard length buffer because of the tube inner void depth, then from there, need to know the weight of the buffer that you have in play as well.

If you have a fixed stock (A1 or A2), then you do not use a carbine buffer in the rifle since the B/C will not be limited correctly at the back of stroke, ending with you cracking the lower receiver (back of the key is going to strike the lower receiver at the tube threaded section to crack it there).


In the case that you have a telescoping stock on the lower receiver, then you have a carbine length buffer in play.  
The carbine buffer is 2.9oz, and would suggest that you buy a Colt H-3 buffer.

The reason for just buying the heaviest H buffer, is the way that buffers are built.  
In side both buffers, there are three internal metal discs.

In the case of the standard buffer, the discs are just standard steel.
In the case of the H3, all the discs are tungsten steel discs, which are much heaver than standard steel.
So between the two buffers, and some disc's swapping, you can cover all the different weights of the carbine buffers.  The H3 may work well, or if needed, you can swap out a disc between the two, turning the standard into a H1, and the H-3 into a H-2.

Carbine buffer, and as stated, pick up a H3 buffer, and between the standard buffer you already have and the new H3, can swap the internal weights between the two to come up  with the needed buffer mass to cycle/unlock the bolt at the correct timing.

Here you go, and just make sure when you reinstall the buffer bumper roll pin, you get it flush with both sides of the buffer side walls.  

If you mean ran fine, as in the bolt is locking back on the catch after the last round out suppressed and unsuppressed after you have gotten a few hundred rounds through the rig to start to foul it up, then you are golden.  

If not, then reserve the T3 for when the suppressor is installed, and the standard buffer for it is not.