I think its going to be tough for people to answer your question.

The RC3 is the only low cyclic increase can in the mix of your options. It is obviously lowest in backpressure as it would have to be to have 5% cyclic increase on full automatic.  Our M4SDK, and Recce 5K are probably our lowest backpressure cans in the currently sold lineup. We are about to release our A2SQD (that took forever), and it is probably lower in backpressure than those other 2, and is an A2 mount, albeit ~7” oal and 19.5 ounces in weight.

The M4SDK is more quiet and has probably a little more backpressure than the Recce 5K.

We have had a lot of people shoot RC2’s and then our cans and prefer our cans, but I don’t know what that says about backpressure.  I’ve only fired maybe 25 rounds through the RC2, all sound testing, and I don’t have enough experience with it to be able to say exactly how it relates to the others in backpressure.

B&T in my limited experience of the A2 mount long rotex can was really a loud, heavy, worthless can in my opinion.

Our A2SQD was designed for consideration by the armed forces (not sure whether they will look at it or not as they often don’t look at options even when they are officially offered for T&E, but that was the intent), and we shot our release footage last summer on a prototype.  The production model replaced two baffles with a higher durability lower backpressure first baffle. So none of the cans except our internal prototype will have that slightly different stack.