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PRI Mk 12 Mod 0 gen III: how gassy with a flow-through suppressor?

carbonbased

carbonbased

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Jul 26, 2018
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#1
Thinking of getting one of these, but absolutely hate gas to the face. I just like the look of them, but am not hung up on clone-correctness.

I have a Surefire RC3 that I’d use on it.

I’m not an AR guru, so if it is indeed a bit gassy even with a RC3 I’m not sure how big a pain it is to install different gas tubes in order to tune it? I’d want to keep that unique gas block as it looks cool.

I assume the handguard needs to come off. The mk12 mod 0 gen III flip-up front sight gas block apparently comes in set-screw and cross-bolt variants, and I’m unsure which one ships with the one I’m interested in.

Perhaps both are equally easy to remove to install a gas tube?

Be gentle, pretty AR-noob here. I might have everything backwards and wrong lol
 
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#2
That barrel looks long ( not much info about the rifle in the link ). I’d say that not only won’t a barrel that long be gassy with your flow through suppressor but you likely won’t need hearing protection if you’re out hunting with it ( high 120’s, low 130’s decibels at the ear with 77 grain ? ).
FWIW
I’ve read that the close tine SF flash hiders don’t work well with the RC3.
 
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#3
I ran a PRI Mk12 Mod 0 that had a Bartlein barrel swapped in and my buddy has a one with the PRI Douglas barrel. We both used the OCM5. Gas is not bad at all. I still have a Mk12 Mod 1 that I felt was a bit over gassed so I swapped the BRT gas tube in. You should be able to easily do that on the Mk12 Mod 0 since the gas block is in front of the handguard, but we didn’t need them with more traditional higher backpressure cans. The RC3 should make it even better.

I ran the Mk12 Mod 1 upper on a buddy’s SOT full auto lower with the OCM5. Cyclic rate was slow and ridiculously soft to shoot. The Mk18 upper I ran with an RC2 is the exact opposite.

Short story is the 18” barrel is going to negate a lot of the gas so you should be fine. And if you want to tame it down further, drop a BRT gas tube in.

Have fun, they are great rifles and one of my favorites to shoot.
 
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#12
A brt tube tamed my LMT 308 big time. The pri mk12 I have is very soft and smooth and gas isn't bad but I still intend on getting a BRT tube for it.

It works as well as an agb but you have to buy multiple tube's if you don't like BRTs guess. You can also pick your own port size and theyhave a guide on howto do that. Personally I don't like AGBs. Once I find a setting and shoot a while theyalways freeze up. I much prefer the BRT.
 
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#13
FUNCTIONAL said:
A brt tube tamed my LMT 308 big time. The pri mk12 I have is very soft and smooth and gas isn't bad but I still intend on getting a BRT tube for it.

It works as well as an agb but you have to buy multiple tube's if you don't like BRTs guess. You can also pick your own port size and theyhave a guide on howto do that. Personally I don't like AGBs. Once I find a setting and shoot a while theyalways freeze up. I much prefer the BRT.
Click to expand...
I kinda want a Riflespeed AGB and just clamp on the mk12’s flip up sight gas block in front of it. Not going to use the OCM5 collar anyway Lol

Follow me for more LARPing tips
 
#15
joe777 said:
You could reach out to them and ask for gas port size of the barrel and the buffer weight. That will determine how much tuning will be needed, if any, to reduce gas blowback.
Click to expand...
I did reach out and the 18” with the carbine buffer tube (edit: it has RIFLE-length gas but an adjustable stock, which means carbine buffer tube) has a 0.089” gas port. Forgot to ask about the buffer weight.
 
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#17
01911 said:
Carbine gas is unfortunate but the RC3 is going to help a lot with sending the gas forward .
Click to expand...

The 18" barrels should be rifle length gas systems, I believe @carbonbased meant he was asking about the PRI model with the carbine buffer tube & collapsible stock instead of the fixed A2 stock version?
 
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#18
An appropriately gassed 18" rifle gas barrel generally is about the LEAST gassy configuration for a suppressed AR. They tend to tolerate a suppression even without fancy tuning tricks. I shot out an 18" MK12 barrel with over 9k rounds and never had a single malfunction, with the majority being suppressed. Didn't use a flow through suppressor or AGB either.

I replaced the barrel (a Nordic 18") with a Centurion MK12 and it continues to perform the same, and is similarly soft/flat shooting.

You won't be sorry you got one! Literally my favorite rifle of all time!
 
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#21
joe777 said:
That's amazing. Some have a .1+ in 18" rifle length gas. I think you'll be fine if you just put in an H2+ buffer. If anything it might short stroke weak ammo
Click to expand...
Hopefully the tech quoted me the right number. He didn’t have it immediately on hand and was shuffling files around trying to find it…I could tell he wanted to get on the next call too.

If somebody feels like it, give ‘em a call to confirm.
 
#22
carbonbased said:
Hopefully the tech quoted me the right number. He didn’t have it immediately on hand and was shuffling files around trying to find it…I could tell he wanted to get on the next call too.

If somebody feels like it, give ‘em a call to confirm.
Click to expand...
I'll give them a call later today. I want to knowbefore I order a brt tube.

I run mine with a h2 buffer andstandard spring. Super soft shooting, ejection is good andhardlyany gas suppressed.
 
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#25
Black max said:
18” carbine gas? 🤮
Click to expand...
As noted above, it’s a rifle gas system.

Because I’m an AR noob I was just being overly careful to describe the gun in question, which is the 18” model with an adjustable stock that rides upon what is apparently called a “carbine-length buffer tube”.

I had considered that perhaps the adjustable vs A2 non-adjustable stock models might have different sized gas ports. As I thought the longer buffer tube on the non-adjustable models would perhaps use different springs and buffer weights, which might slightly change the port size, etc etc rabbit hole etc.

Sorry for the confusion.
 
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#27
DeathBeforeDismount said:
Swap the carrier out for a bootleg. Easiest, cheapest and less intrusive way to adjust the gas.
Click to expand...
I liked this idea until I read that the Bootleg-type carriers make the ejection port noise quite a bit louder.

Even though I wear ear pro 100% of the time, I’ve got a janky left ear that has problems even when doubled up (I don’t understand it either). So I’m trying to minimize noise at the ear.

Otherwise it seems like a good solution.
 
#32
FUNCTIONAL said:
Plot thickens.

PRI said their gas port on a 18" spr barrel is .106"

This actually tracks with what the spec for a mk12 barrel from crane called for. I thought the number @carbonbased seemed small.
Click to expand...
Lol I’m glad you double-checked.

I think I’ll triple-check when I have the chance. I had a feelin’…
 
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