Blowback PCCs and Cans, and Blowback

[1168]

I do a lot of shooting with a 12” straight blowback PCC AR with a Rex Silentium .458 MG7k. For comparison, I have or have access to, mostly .45 pistol cans, and a Dead Air Odessa. I have a pair of CGS MOD9s in purgatory, which does me no good. In other words, I don’t have much basis of comparison on this type of host.

Anyway, the .458 can does a pretty good job, but I sometimes find myself contemplating getting a 9mm twin, or perhaps something else along those lines. For better sound suppression, not that its really needed.

So my question is this: would a 9mm MG7k just increase blowback, making the gun dirtier and louder at the ear? Or is 9mm low pressure enough that that’s not a thing? Would the calculus change if the host was a radial-delayed blowback?

[MegademiC]

In theory, the delayed blowback would help a lot because the pressure can drop before the chamber uncorks.

A heavy bolt really helped cut blowback in my m11, though im sure ROF was a big factor as well.

[Eurodriver]

I'm the opposite. I only have 9mm cans so I cannot tell you what would happen.

I have a 45 can in jail for about a month now - so if you give me 5-6 more months I will be able to compare apples to apples on a B&T and an SMG.

[1168]

I'm the opposite. I only have 9mm cans so I cannot tell you what would happen.

I have a 45 can in jail for about a month now - so if you give me 5-6 more months I will be able to compare apples to apples on a B&T and an SMG.

When I get back, we’ll have to do some testing.

[utahjeepr]

Delayed blowback would probably help way more than going to a 9mm can. Can't say for sure cause I run a 45 can myself.

My 9mm AR had a ton of ejection port bark at first (JP SCS Buffer with all tungsten weights). After a bit of experimenting I ended up using a 12 ounce buffer to quiet the ejection port noise. It seems to slow the blowback "just enough". Kind of a "just add more mass" delayed blowback system.

[czgunner]

I don't really notice any gassing from my Stribog gen1 and my can. I'm a lefty, so I get gassed out pretty easily with a lot of setups.

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[Pappabear]

I can only say that shooting larger caliber cans is my preference. Less blow back and less of a chance for a baffle strike. I shoot my 45 can on my MPX and love it. Dedicated can for the MPX. I wish it was a later gen AAC can that can be made smaller like my newer 9mm cans on my MP5 and APC. Love that modularity.

PB

[RHINOWSO]

I too have a Tirant 45 (older one) and use it on PCCs, zero blowback on 9MM AR and Scorpion shorties.

[TMS951]

I have a B&T APC9 and AAC tirant45m and a tirant9m.

I’ve tried the 45 a couple times and it was noticeably louder. Neither has much blow back.

Honestly my 45 can is my least used can and my 9 is used so much I wish I had bought an omega 9k instead of the Tirant45.

Honestly 45 suppressed kind of sucks and I was super disappointed.

[1168]

I have a B&T APC9 and AAC tirant45m and a tirant9m.

I’ve tried the 45 a couple times and it was noticeably louder. Neither has much blow back.

Honestly my 45 can is my least used can and my 9 is used so much I wish I had bought an omega 9k instead of the Tirant45.

Honestly 45 suppressed kind of sucks and I was super disappointed.

So, for you, having both 9mm and .45 cans of similar design, and a 9mm blowback host, if you currently only had a .45 can for that host, you’d find it worthwhile to get a 9mm can? If there’s no increase blowback and its quieter, I can’t see a downside, and I could use the MG7k .358 on rifles, too. The scenario I’d want to avoid is one in which its quieter at the muzzle, but poppier at the ear and gassy.