Re: what "can" is this
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The Uzi design is different, the whole barrel/nut assembly is shortened. Same thing on the M3A1 and the SW76 (all early designs, all three somewhat different.)
It is not a back pressure issue, but rather an entrapment issue. It goes like this...modern designs, truly modern designs utilize what is called forward purge or self purging baffles. These baffles, aside from utilizing the newer baffle tone shift cuts (those odd football shaped conical machining surfaces) also allow for a majority of debris to be blown out the front of the can. This is a complicated design as the gas pathing has to be super efficient, allowing for the dwell time to be high enough for world class heat suppression while still allowing for enough gas movement to eventually work everything out the front. You have heard this before from myself and others, know it to be true..the is no reasons, zero, nada for a well designed centerfire suppressor to be able to be opened up..and a whole host of reasons why they shouldn't.
Reflective designs fail in this regard. Reflective designs start off by directing the hottest, high debris component part of the discharge BACK into a part of the can that is nearly impossible to purge out. It is exactly the wrong way to get the job done. Too long, too entrapment prone and worst off all, covers as much as 15% of the barrel at it right where it is usually thinnest and needs cooling the most. Heat dwell is too long, debris settles and eventually ruins performance...and on and on.
Most major manufacturers made reflective cans, all but a few have abandoned them. 1/2 the size, much cleaner, much quieter and much more accurate, blast cans outperform. As an example there are three (3) major .338 solicitations right now (two settled, one outstanding) the issue was accuracy and quiet. Blast cans already selected on two of them.
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