Okay, part of the issue here is I'm confusing the threshold modifier (Threshold 3 if hermetically sealed) listed in the text with the dice pool modifier on the table (-1 if encased in plastic.) Now the question is do they stack?
No that's solved lets do a short table for a rating 4 chem-sniffer
<10 rounds, Hermetically Sealed, not "in plastic", ~11%
>10 rounds, Hermetically Sealed, not "in plastic", ~21%
<10 rounds, Hermetically Sealed, in plastic, ~4%
>10 rounds, Hermetically Sealed, in plastic, ~11%
<10 rounds, not sealed, in plastic, ~26%
>10 rounds, not sealed, In plastic, ~41%
<10 rounds, nothing special, ~41%
>10 rounds, nothing special, ~54%
I think my math is right...
I am not trying to smuggle a gun that doesn't hit at least 11% on this chart anywhere we have Lone Star on standby. So that means the PSK-3 with ammo in a separate case, or the H&K with it's sealed magazine provided the modifiers stack. If the H&K could be obtained with <10 round magazines then it would be the superior gun, and I'm certain home manufacture would be allowable but don't; ask me the tests. As long as they don't find the gun itself the H&K is a comparable and cheaper option. What concerns me is the inability to modify the H&K, it's inability to hide in plain sight, the fact it does not have a Machine Pistol option. What the H&K does not say (and is to its advantage) is that the silencer is the same availability as the weapon, like the PSK-3.