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KMO 05-15-2011 06:50 PM

Factory Barrel Thread Size?
I have a 580-series tactical Mini-14 with the factory flash hider on it. I removed the flash hider for some R & D, and the factory barrel thread size is 9/16" x 24 RH. Has anyone found their threaded factory barrels to have any other thread size than this? I can't imagine so, but I don't want to commit on a new project if Ruger made any changes after the 580-series...Please confirm if you've checked your newer versions with factory-cut threads...;)

mrm14 05-15-2011 07:49 PM

My 580 has 9/16X24 RH threads. I bought it new in December of 2008.

KMO 05-16-2011 12:09 PM

This seems odd to me...I have not confirmed it yet, but apparently 2009 & later Mini's are threaded 1/2-28 (.223) and 5/8-24 (6.8 and Mini-30). :confused:

Where is Gundoc on this? Is he not monitoring this forum?

GunDoc 05-17-2011 01:12 PM

I've heard rumors and maybe even a magazine piece that said Ruger was using 1/2x28 on some Minis, but everything through my shop has been 9/16x24 in the 14Tacticals.

9/16x24 has been used since the GB models. I've found the barrels didn't require turning to major diameter (at factory length), just a truing cut if anything.

While I want to believe that Ruger would use a standard AR thread for the .223 I'll only believe it when I see it. Using 9/16 allows for using the existing molds/parts and in keeping with Ruger philosophy doesn't allow the average Joe to install parts that may not have sufficient exit diameters or require exact alignment to be safely used.

I've tried to reach my source at Ruger to confirm thread specs but I've been unsuccessful thus far.

KMO 05-18-2011 03:41 AM

Whoa! That profile photo is ominous...Thanks for that info on the thread sizes. I'm starting to think that the 1/2" x 28 is a rumor. Frankly, since they're using the same newer flanged barrel, what would the logic be in cutting down the thread size from 9/16" x 24? I don't mind calling the east coast Ruger shop, but they're never as friendly on the phone as the Prescott folks are, especially when I ask questions about specs & dimensions. On second thought, I'll have my wife call instead...:cool:

KMO 05-20-2011 11:25 AM

Well, we confirmed that Ruger did, in fact, change the thread size on their threaded barrels to 1/2" - 28. We were checking into this because of the demand for a Mo-Reaper that would fit the Mini's with the factory threaded barrel. While momentarily boggled by the obstacle of two thread sizes, we settled on a concept yesterday that should work for either barrel. So, for the factory tactical Mini-14 with a factory flash hider, the flash hider can be removed, and our Reaper unit put in its place. The finished install will have the total barrel length nearly identical. And, since flash hiders are illegal in CA, but muzzle brakes are not, we can actually offer a solution to CA Mini-14 fans who could not previously consider a purchase of the factory tactical version. I should have a photo up for this new prototype in a few days...;)

KMO 05-24-2011 03:50 AM

We broke out of our mind cramps and came up with a solution...This prototype Mo-Reaper for the factory tactical Mini-14 will fit either of the two thread sizes, and it doesn't add any length to the barrel...

plumbernater 08-09-2011 12:45 AM

Now that looks nice. You have some nice stuff lots of luck with the new Mo Reaper

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