MP5 SD suppressor design - Blast chamber

[VX666]

Working on a second form 1 design for a MP5 SD can

Got a question on the venting of the blast chamber- I noticed that some designs have bent holes on the barrel spacer nuts and others don't.

Should I try this design with vent holes and if so could there be issues? Any advantages?

[a_canadian]

If you're talking about vent holes going back into a reflex volume, a portion of the can extending back over the barrel, then one advantage is a reduction in pressure on your blast baffle and to the baffle stack overall. Maybe not a massive difference but something. And suppressor efficiency is largely about adding up all the little benefits you can I baffle design volume, spacing, etc. Some reports suggest there is no advantage in reflex designs over muzzle-forwsrd cans. In my limited experience there's a small advantage acoustically. A couple or a few decibels.

A potential disadvantage might be soot buildup on the barrel, making removal more challenging after a time. The rear plug of the tube has to deal as well, whether threaded or with O-rings (wouldn't recommend the latter for anything more intense than 9mm though), and that closely fitted part has to slide along the dirty barrel for removal in most designs. You can get around this sometimes by making a larger threaded anchor point for the whole can at the back end, running it onto matching threads on a barrel nut perhaps, which allows the can to pull off easily once unscrewed. The muzzle spacer would then be a slip fit, unless you are able to coordinate thread timing between two sets of threads of different sizes which could be challenging.

[VX666]

Well this for the MP5 SD so it's a bit unique in some respects

I think havingvthe vents would reduce pressure and possibly risk FTC.

My only concearn is will it reduce heat noise.