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Discussion Starter · #1 · (Edited)
I’ve been acquiring the parts for a USMC DMR for a long time and just finally scored an M2A stock. Now I’m looking for a builder. Caveat is this…

It’s the OPS Inc variant. I have the OPS Inc 12th model M14 brake as well as the USMC barrel sleeve and gas cylinder spacer. I have installation info from the late Phil Seeberger of OPS Inc as well as Ron Allen, but not confident I can install these parts myself.

Looked around and don't see any OPS Inc builds. Has anyone here done this variant? Who did the work?


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That’s going to be a very unique build for sure. I don’t know of anyone who has built one with the OPS Inc suppressor collar. I recall that Ron Allen had to individually fit the collar to the specific barrel based on the tiny amount of threads, and that timing was a challenge. He noted the suppressors (and maybe collar part?) was serialized to a specific DMR rifle and not to be swapped for the same reason. Hopefully Forceman can help you out, but curious what info Ron provided and if could share the install info, etc. Good luck and keep us posted.
 

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I hope you share this build after it's complete. I thought about building this same one. I would just need another stock.
 

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Discussion Starter · #6 · (Edited)
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Some things Phil and Ron mentioned regarding installation, the barrel sleeves were actually press-fit on the Krieger med-weight DMR barrel. There’s simply not enough OD possible in the M14 barrel to machine a step like you can on an AR. Slight undervariations in OD were addressed using shim stock wrapped around the barrel, as needed. Or the sleeve was rebored to fit the barrel if barrel OD was larger. I can imagine a PWS armorer with a box of these available would simply test fit several until the right fit was achieved on the particular barrel they were working on. The conundrum was that the sleeve was never to be allowed to contact the figure-8 as that would affect accuracy. A 1/8” clearance was ideal. Being quite familiar with the Mk12 SPR and it’s fixed barrel collar, I could never figure out how you could press-fit the DMR sleeve, especially with shim stock, tight enough to prevent the sleeve from moving backward against the figure-8 when the 12th model suppressor was screwed on and tightened appropriately.

Other interesting info Phil mentioned, the barrel sleeve, when properly fitted, actually enhanced the accuracy of the platform by making the barrel in front of the gas cylinder stiffer, as if the OD was increased. They were seeing much tighter groups with the sleeve installed compared to no sleeve due to reduced barrel whip.

The wrinkle in my knowledge has to do with the spacer that straddles the bands on the gas cylinder. I have that too, but received much later from a different source. It’s just a tube with similar inner diameter as the sleeve. Phil said there was no such spacer used despite it being clearly visible in photos I showed him (he was old). My best guess is Phil’s installation procedure with the sleeve not touching the figure-8 might have been revised at PWS, possibly without his knowledge. I understand the disruption of the harmonic if the sleeve were to touch, but on the other hand if the spacer is also press-fit and making contact with the gas cylinder bands, then everything is supported aft of the figure-8 and the barrel sleeve could then be tensioned in-contact with and against the figure-8 with the muzzle brake. Everything would seem to be supported, thus accuracy is kept intact if not enhanced. This way the entire set-up would be sandwiched between the muzzle brake and the 90-degree gas cylinder stop on the barrel, everything in contact and supported. But this is my conjecture as there seems to be no other purpose for the spacer.
 

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Discussion Starter · #7 ·
That’s going to be a very unique build for sure. I don’t know of anyone who has built one with the OPS Inc suppressor collar. I recall that Ron Allen had to individually fit the collar to the specific barrel based on the tiny amount of threads, and that timing was a challenge. He noted the suppressors (and maybe collar part?) was serialized to a specific DMR rifle and not to be swapped for the same reason. Hopefully Forceman can help you out, but curious what info Ron provided and if could share the install info, etc. Good luck and keep us posted.
Ron spends every Sunday on custom collars for customers with odd barrel lengths or screwed up collar steps so that the suppressors screw on tight within 6-8 turns. Poor guy works too much.

Thankfully the M14 DMR barrel sleeve has a fixed length so that the proper number of turns is built in.
 

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I have also recently sourced some parts for the build. I have been tossing the idea around of doing the suppressed route as well. I have been trying to gather information for this. Thank you for the topic.
 

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Discussion Starter · #10 · (Edited)
I have also recently sourced some parts for the build. I have been tossing the idea around of doing the suppressed route as well. I have been trying to gather information for this. Thank you for the topic.
Most people become unimpressed and frustrated when trying to suppress the M14.They become over-gassed when a suppressor is attached, which makes for a loud gun with lots of gas in your face.

The single best thing you can do if you want to run the M14 suppressed is to find a BPT gas piston with the .062” gas port. There weren’t many made, but limiting the gas going into the system is the best way to alleviate all the issues with simply screwing on a suppressor.

I don’t know how the USMC ran theirs with the OPS Inc suppressors, but it definitely wasn’t an ideal platform for it.

ETA: I tried to get Sadlak to do a run of gas pistons in this spec many years ago, but couldn’t get them interested. Times have changed, might be a good good buy opportunity if there was enough interest.
 

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Most people become unimpressed and frustrated when trying to suppress the M14.They become over-gassed when a suppressor is attached, which makes for a loud gun with lots of gas in your face.

The single best thing you can do if you want to run the M14 suppressed is to find a BPT gas piston with the .062” gas port. There weren’t many made, but limiting the gas going into the system is the best way to alleviate all the issues with simply screwing on a suppressor.
Yes, I had a similar conversation with Ron Allen re the gas piston topic a couple of years ago. Too bad such pistons are not available. Another needed option is probably a vented gas plug that allows excess gas to escape. Lee Emerson's book has some interesting info re the early 1990s XM25/M25 rifles used by US Army Special Forces, and noted the following:

"For sound suppressed M25 rifles, the U.S. Army welded and drilled the gas piston inlet to a smaller diameter and also drilled an approximate 0.030" diameter hole in the center of the gas cylinder plug in order to keep the chamber pressure and the force acting on the operating rod to acceptable values."

I'm tempted to have some extra gas piston's welded-up and re-drilled with the small hole as noted above, but I don't know if the weld will hold given the extreme temperature and pressures involved.

Digressing somewhat, but a respected forum member has reported that the OSS suppressor's work well on M1As given that excess combustion gases are vented out the front of that unique suppressor:
...so it's not historically 'correct' for a replica DMR rifle, but it seems very well-suited to the M1A's gas-port actuated system. This might be the option I choose when I go down that road.
 

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JD, can you elaborate re welding rod used, and if you polish the interior afterwards to remove material so it’s flush with interior?

Fwiw, I recently acquired some spare USGI pistons…all but the bottom one are in spec. Maybe I could have some welded up, just to see…
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I've cross drilled a number of spindle valves with a .052 bit and those who have them have indicated they work fine, eliminate blow back and still allow the rifle to function with standard loads.
 
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