MK12 Mod 0 300 Black Out is completed

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Jeff in Texas
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Location: J&D Ranch North Central Texas

MK12 Mod 0 300 Black Out is completed

Post by Jeff in Texas »

Finally got the 300 Blk Out Mk 12 Mod 0 completed. Took it out to the range this morning for the testing. Supersonic loads loads shoot .75" moa at 100 yards. The 208 gr Hornady AMAX sub sonic loads shoot a hair under 1 moa which blew my mind. Wow is it accurate with both super and sub sonic loads! This is such a fun gun to shoot though I do have one issue. I've got the adjustable gas block wide open. It ejects rounds just fine but won't cycle another round. Talked to my smith and he said he'd have to open the port a bit.

It's not an exact clone of the MK12 Mod 0 but it's about 90%

CMMG Lower with A2 stock
MK12 MOD-BLK Upper:
Oden 16.1" pistol gas block barrel
PRI Gas Buster Charging Handle
PRI Full Length Forearm
PRI MK12 MOD 0 Rail
PRI Flip up Front and Rear Sight
ARMs #22 Throw lever Scope Rings
Leupold VX-R 2-7X33 FireDot Duplex Recticle Scope
MagPul MS3 G2 QD sling
Ross Precision 30 Cal titanium Suppressor

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Distance is not the issue, but the winds can make it interesting!

John 3:1-20
MisterHelix
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Re: MK12 Mod 0 300 Black Out is completed

Post by MisterHelix »

Nice lookin' stick.
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Dr.Phil
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Re: MK12 Mod 0 300 Black Out is completed

Post by Dr.Phil »

Your front and rear rings are reversed.
The throw levers should point towards each other when closed.

Glad you were able to find a budget option for this build.
Enjoy!
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don't tell them where they know the fish."
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BlogSarge
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Re: MK12 Mod 0 300 Black Out is completed

Post by BlogSarge »

For the cycling issue;

Is your gas block aligned properly?
Have you tried a low-mass BCG?
Have you tried a lighter buffer?

Others with a more intimate knowledge of cycling issues will hopefuly chime in...


Still, it is a nice looking build and you should be proud of it and the shooting so far..
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Jeff in Texas
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Location: J&D Ranch North Central Texas

Re: MK12 Mod 0 300 Black Out is completed

Post by Jeff in Texas »

Dr.Phil wrote:Your front and rear rings are reversed.
The throw levers should point towards each other when closed.

Glad you were able to find a budget option for this build.
Enjoy!
Phil,

I didn't pick up on the scope rings until you said something. Just made the change and will sight in after lunch.

Any thoughts on the cycling problem. Opening up the gas port seems a simple fix. Thought?
Distance is not the issue, but the winds can make it interesting!

John 3:1-20
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SwampDog_13
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Re: MK12 Mod 0 300 Black Out is completed

Post by SwampDog_13 »

Do you know what size gas port you currently have? What buffer/spring setup? A suppressed 16" pistol gas gun doesn't scream undergassed to me.
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Jeff in Texas
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Location: J&D Ranch North Central Texas

Re: MK12 Mod 0 300 Black Out is completed

Post by Jeff in Texas »

SwampDog_13 wrote:Do you know what size gas port you currently have? What buffer/spring setup? A suppressed 16" pistol gas gun doesn't scream undergassed to me.
I have no idea when it comes to the size of the gas port or buffer spring? The spring is what came in the stock? I went on Odin's website and it doesn't specify gas port size.
Distance is not the issue, but the winds can make it interesting!

John 3:1-20
jwb47
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Re: MK12 Mod 0 300 Black Out is completed

Post by jwb47 »

very nice rifle I hope you get it sorted out .
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John A.
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Re: MK12 Mod 0 300 Black Out is completed

Post by John A. »

It may be an issue of the (heavy) rifle stock buffer and spring.

A carbine buffer (the lighter of the bunch) are about 3.1 oz

A rifle buffer is over 5 ounces.

Not including the buffer spring is a heavier "weight" spring too (and longer).

That's probably not doing you many favors in terms of cycling.
When those totally ignorant of firearms make laws, you end up with totally ignorant firearm laws.
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Luke2236
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Re: MK12 Mod 0 300 Black Out is completed

Post by Luke2236 »

Very nice looking rifle!
Canadian Coast Guard - Retired
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