Thank you Form I’m now a mk12 believer

[77TMK]

Reviving this as in the market for a precision ar. Any benefit in a mk12 mod 0 as opposed to a geissele super duty?

The super duties are not necessarily "precision" rifles, and most Mk12 Mod 0 builds I have used are with average barrels. If you want a turnkey AR, the most cost effective yet also significantly most precise setup will be a SOLGW Broadsword upper with their SPR barrel and L89 rail.

If you really like the PRI forend, grab a forend, thermal-fit receiver, and SOLGW SPR 16-18" barrel. I've tried WOA, Douglas, Krieger, Bartlein, and BA "mk12" type barrels, and none of them were in the same league as the SPR barrels SOLGW sources. The 5/8x24 muzzle is a genuine benefit, and the source of the SOLGW SPR barrels (BHW) is unique.


More precise but more expensive will the Ridgeline rifle.

 

[RockAndSage]

More precise but more expensive will the Ridgeline rifle.

Are the Ridgelines really more accurate than PRIs or the Brouwers?

 

[Avonac]

Are the Ridgelines really more accurate than PRIs or the Brouwers?

I’ve never shot a PRI or Brouwer but my Ridgeline is a hammer. My test target was a .4 and I have killed Prairie dogs past 700 yds. It’s the softest shooting precision AR I have shot

 

[bascott1]

Can’t find a ridgeline in stock anywhere

 

[omicron1792]

@Formidilosus and others.

I have this m4. It has factory colt 1:7” barrel at 16”. Free floated hand guard. Upgraded trigger and bcg. Adjustable stock.



What accuracy benefits would I see with a MK 12? Would it just be the longer heavier Douglas barrel?

 

[77TMK]

Can’t find a ridgeline in stock anywhere

They are very small batch rifles. Next best bet is the SOLGW SPR / Broadsword ones. You could alternatively just buy the barrel and handguard, and build it. Do you know how to properly assemble one, or someone nearby who does?

 

[Avonac]

@Formidilosus and others.

I have this m4. It has factory colt 1:7” barrel at 16”. Free floated hand guard. Upgraded trigger and bcg. Adjustable stock.

View attachment 1094636

What accuracy benefits would I see with a MK 12? Would it just be the longer heavier Douglas barrel?

You are most likely going to see better performance with the Douglas barrel. Another benefit is going to be how the receiver and handguard lock up. This is going to be a big benefit to mitigate poi shift from different positions.

 

[justinspicher]

Can’t find a ridgeline in stock anywhere

WTS Thread 'Ridgeline Defense LPR Upper'

Jan 20, 2026

Lightly used. Maybe 70rds through it. Complete upper as sold from Ridgeline. (suppressor, lower, scope, mount, etc not included) I had to slightly file the front and rear takedown pin tabs for it to fit my Larue lower. Still has an extremely tight fit and did not impede function with other lowers I tried it on.

$1500 shipped

• low2497
• Replies: 6
• Forum: Gun & Gun Parts Classifieds

Not a full rifle or new, but……

 

[Steel Rain]

Reviving this as in the market for a precision ar. Any benefit in a mk12 mod 0 as opposed to a geissele super duty?

I have the PRI MK12 Mod0 and two 16” Super Dutys. They are all extremely accurate but different. The SDs are my boys’ rifles. I will add a short barreled SD to the safe in the future. The SD triggers are amazing. That all being said, I’ll never part with my MK12.

 

[bascott1]

They are very small batch rifles. Next best bet is the SOLGW SPR / Broadsword ones. You could alternatively just buy the barrel and handguard, and build it. Do you know how to properly assemble one, or someone nearby who does?

Yeah. Got a good buddy that’s really good with them.

 

[bascott1]

I have the PRI MK12 Mod0 and two 16” Super Dutys. They are all extremely accurate but different. The SDs are my boys’ rifles. I will add a short barreled SD to the safe in the future. The SD triggers are amazing. That all being said, I’ll never part with my MK12.

Like the mk12 that much more? Wanting a do all rifle, shoot deer, matches, varmints and just have fun with. The mk12 seems like it fits that bill

 

[Floridave]

What is the practical difference between a MK12 clone and free floated ar15 with 18 inch barrel with rifle length gas system and fixed stock with rifle length buffer tube?

Well i guess i answered my own question below.
After perusing this thread it made me wonder, as when I built whats now my primary AR, I patterned it to follow those MK 12 attributes but using modern readily available parts. Not having been in the military I didn’t have the attachment to a particular historical correct version.

-—————————————————-//
The practical difference comes down to historical replication versus modern optimization. While both feature an 18-inch barrel and rifle-length gas/buffer systems, a genuine Mk12 is a heavy, mission-specific military clone, whereas a modern AR-15 build provides equal precision with significantly less weight and better modularity.

Practical Outcomes for the Shooter
* Handling and Maneuverability: The military Mk12 was designed to be a designated marksman rifle, heavily weighted so the shooter could maintain a stable platform. A modern equivalent build uses lighter materials and slim M-LOK rails, making it vastly superior for off-hand shooting, transitions, and carrying over long distances.
*
* Barrel Profiles and Heat: The Mk12's heavy barrel retains heat well during extended, rapid strings of fire. Modern ARs use lighter profiles that heat up faster but handle better; to mitigate this, modern builders often choose fluted or carbon-wrapped barrels that maintain stiffness without the extra weight.
*
* Suppressor Integration: The Mk12 platform requires the dedicated OPS Inc./Allen Engineering brake and collar system to mount its legacy suppressors. A modern build uses standard threading, allowing you to choose from hundreds of modern, lightweight suppressors on the market without being locked into a single mounting ecosystem.
*
* Accuracy and Parts Availability: Both setups are mechanically capable of consistent hits past 600 meters using match-grade 75- or 77-grain ammunition (like Mk 262). However, a modern build uses standardized mil-spec parts, making maintenance, repairs, and swapping components significantly easier than sourcing proprietary Mk12 parts.
*

Sent from my iPhone using Tapatalk

 

[Choupique]

What is the practical difference between a MK12 clone and free floated ar15 with 18 inch barrel with rifle length gas system and fixed stock with rifle length buffer tube?

Thats been covered, and your summary is largely inaccurate. Yes a real mk12 is heavier than an M4, and thats about all it got correct. SPR barrels are threaded 1/2x28, parts are standard except the handguard and barrel nut, etc.

I think its been stated here that a real mk12 is a system that is more than the sum of its parts. I own a standard AR with a 16" SPR profile barrel and OCM5 and while it does shoot really good, it doesnt pound out sub-MOA groups like the real thing does.

 

[omicron1792]

Thats been covered, and your summary is largely inaccurate. Yes a real mk12 is heavier than an M4, and thats about all it got correct. SPR barrels are threaded 1/2x28, parts are standard except the handguard and barrel nut, etc.

I think it’s been stated here that a real mk12 is a system that is more than the sum of its parts. I own a standard AR with a 16" SPR profile barrel and OCM5 and while it does shoot really good, it doesnt pound out sub-MOA groups like the real thing does.

Not to be mean, but this makes zero sense.

Your answer of “it’s greater than the sum of its parts” says nothing about why it shoots more accurate. Especially if your m4 basically has the same parts

 

[Choupique]

makes zero sense

Im not the most educated on it. The stiff forearm and the way it attaches to the upper seems to be the biggest peice of the magic, aside from the really good barrel and ops suppressor.

Far as I know, everything aft of the barrel nut is standard stuff. You can take the ops brake off and put whatever you want on the muzzle. The reciprocating parts are all standard. The lower is a standard rifle lower.

If you just build a regular free floated AR with a really good barrel you might get good accuracy from it, but you wont get the full package the mk12 gets you - minimal POI shift from forearm pressure, minimal POI shift with/without the can, exceptional reliability and durability, etc.

 

[omicron1792]

Im not the most educated on it. The stiff forearm and the way it attaches to the upper seems to be the biggest peice of the magic, aside from the really good barrel and ops suppressor.

Far as I know, everything aft of the barrel nut is standard stuff. You can take the ops brake off and put whatever you want on the muzzle. The reciprocating parts are all standard. The lower is a standard rifle lower.

If you just build a regular free floated AR with a really good barrel you might get good accuracy from it, but you wont get the full package the mk12 gets you - minimal POI shift from forearm pressure, minimal POI shift with/without the can, exceptional reliability and durability, etc.

Ugh. Mk12 is known for its accuracy. I have never heard it is more reliable than other mil spec AR platforms.

If the AR has a free floated handguard from reliable company like bcm, then how would it cause any more poi shift than mk12?

How would heavy can like AEM5 not cause more shift than a modern lighter can?

I started my question with a heavier longer barrel causing better accuracy. I still think that “may” be the case. I hear all the time here that sporter tikka and Blaser barrels have just as much accuracy as the thicker match barrels.

But even if that’s the case, I really haven’t heard anything else that points towards more accuracy with an mk12 besides the barrel.

No doubt they put together a good package when they made the spr. But I think modern upgrades probably have passed it by now. And, that is probably one of the reasons the military retired it for modern upgrades.

 

[RockAndSage]

Ugh. Mk12 is known for its accuracy. I have never heard it is more reliable than other mil spec AR platforms.

If the AR has a free floated handguard from reliable company like bcm, then how would it cause any more poi shift than mk12?

How would heavy can like AEM5 not cause more shift than a modern lighter can?

I started my question with a heavier longer barrel causing better accuracy. I still think that “may” be the case. I hear all the time here that sporter tikka and Blaser barrels have just as much accuracy as the thicker match barrels.

But even if that’s the case, I really haven’t heard anything else that points towards more accuracy with an mk12 besides the barrel.

No doubt they put together a good package when they made the spr. But I think modern upgrades probably have passed it by now. And, that is probably one of the reasons the military retired it for modern upgrades.

@Formidilosus , these are some really interesting questions, I'd enjoy hearing your thoughts on them.

 

[omicron1792]

@Formidilosus , these are some really interesting questions, I'd enjoy hearing your thoughts on them.

Me too.

I asked AI this question. It said

1. MK12 were built to tighter tolerances. This makes sense for truly military made mk12. But would this be the case for clones? Are builders making them to tighter tolerances than other 3k dollar AR? They use any old lower, so a quality build of an AR should fit the same as quality built mk12 clone.

2. It said the chamber was built different for less jump to use the 77gr ammo. I have no idea if this is true. And if other ARs don’t do the same thing now.

Really it. Besides the Douglas match grade 18” barrel and carbon fiber floated handguard.

 

[Choupique]

AR has a free floated handguard from reliable company like bcm, then how would it cause any more poi shift than mk12?

The mk12 pic rail crosses over from the reciever to the forearm to tie it in, and the barrel nut is a special design that I believe distributes pressure onto the reciever rather than the barrel.

How would heavy can like AEM5 not cause more shift than a modern lighter can?

2 point mounting. The physics are dramatically different than having a cantilever load hanging off the muzzle, which is what normal OTB suppressors do as well.

Like I said, Im no expert on them. Mine is a TEMU version. I am an engineer though, and ive seen a real one. Its very apparent that the design is extremely well thought out within the confines of what the AR platform gives you to work with. If you think about the things that a detriment to repeatable accuracy in the field with an AR, it addresses most of them. Ideally, it would have a gas system as long as the barrel which is what Brouwer does, and even further tuned to one specific load would be ultimate.

For an upper than you can slap on any lower and have a true 1 moa AR, a PRI MK12 mod 0 is about as good as you can do. I dont think any regular ol free floated upper will give you the same results with 100% consistency.