I have heard of some companies using 1/2 24 on 300 it is pretty unusual. You can always pop the one you have off and measure. If it does turn out to be 1/2 just make sure you get one compatible with .30 caliber. Don't want to blow the end off your muzzle device.
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MCX Legacy 300BLK 9" Barrel Thread Pitch Question
So I called Sig Sauer to ask what thread pitch was on the MCX Legacy 300BLK I recently acquired with a 9" barrel. I was told it was 1/2x28. Is that typical? Most of the literature I could find shows the 300BLK versions having the typical 5/8x24 pitch. I am ordering an ASR muzzle device and want to make sure I got the right pitch. I called Sig and gave them my serial number and all that. It just seems odd. But then again, it's Sig!
Thanks for any info you might have.
Thanks for any info you might have.
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I have the 9” MCX Virtus and just put a muzzle device on it. 300 blk barrels are 5/8” x 24. I would imagine the legacy MCX is the same. The 5.56 barrels are 1/2” x 28.
5/8x24 on the 300
A 2016 legacy MCX manual agrees with TacoJoe. The 300BLK has 5/8x24 threads.
Bill
Bill
I saw all of that info too. The owner of the LGS where I bought it mentioned it looking like a 1/2x28 which is why I called Sig. Who then verified it being 1/2x28. So is it two bad opinions? Just seems weird. I guess I'll just try and slap an ASR mount on it and find out the hard way haha.A 2016 legacy MCX manual agrees with TacoJoe. The 300BLK has 5/8x24 threads.
Bill
Let us know what it ends up being. I’d be really surprised if it’s 1/2 x 28. I am curious now. I could be wrong. You could go to Home Depot or a hardware store and buy a nut with 1/2 x 28 threads and see if it fits. It may save you some time and money. Or try using a thread gauge and micrometer.I saw all of that info too. The owner of the LGS where I bought it mentioned it looking like a 1/2x28 which is why I called Sig. Who then verified it being 1/2x28. So is it two bad opinions? Just seems weird. I guess I'll just try and slap an ASR mount on it and find out the hard way haha.
Yea I'm definitely curious too. Seems like this should've been an easy answer 😕Let us know what it ends up being. I’d be really surprised if it’s 1/2 x 28. I am curious now. I could be wrong. You could go to Home Depot or a hardware store and buy a nut with 1/2 x 28 threads and see if it fits. It may save you some time and money. Or try using a thread gauge and micrometer.
The 1/2x28 thread pitch is for 5.56 NATO, not 300BLK. As a practical matter, some 5.56 MCX models are not also made in 300BLK. So the manual can sometimes be confusing as only 1/2x28 is listed since 300BLK doesn't exist in the CQB and Tactical Patrol (not to be confused with the Patrol) apparently.
Bill
PS: SIG does NOT want you to be able to direct thread a 5.56 can on a 300BLK barrel as the kaboom would cause SIG to be liable. B
Bill
PS: SIG does NOT want you to be able to direct thread a 5.56 can on a 300BLK barrel as the kaboom would cause SIG to be liable. B
Don't forget to use the correct taper cap if you aren't using a muzzle device with a Sig taper.
Sent from my iPhone using Tapatalk Pro
Sent from my iPhone using Tapatalk Pro
Just bought one! The 5/8x24 Sig ones are sold out everywhere bur KAK makes them and MidwayUSA just listed them for sale!Don't forget to use the correct taper cap if you aren't using a muzzle device with a Sig taper.
Sent from my iPhone using Tapatalk Pro
Ok update: it is indeed the 5/8x24 thread pitch. I gave Sig my serial number and everything when the CS agent told me it was in fact 1/2x28. Not sure how they screwed that up knowing it was a 300BLK buy hey, you guys were right and I appreciate it!The 1/2x28 thread pitch is for 5.56 NATO, not 300BLK. As a practical matter, some 5.56 MCX models are not also made in 300BLK. So the manual can sometimes be confusing as only 1/2x28 is listed since 300BLK doesn't exist in the CQB and Tactical Patrol (not to be confused with the Patrol) apparently.
Bill
PS: SIG does NOT want you to be able to direct thread a 5.56 can on a 300BLK barrel as the kaboom would cause SIG to be liable. B
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