So I purchased this item and it took a few weeks to come, no problem. So I unbox, add some more oil, function check. Took it out to the range. It jammed or no fire 9 times. Ones the jamming stopped, it fired 1 round at a time. So I change the firing pin. Like I have read about in forums, Boom, Boom it goes. After 50rd the barrel/Handguard is screwing off. I will take it to a gunsmith to get it fixed. Not going to send it back cause it will take to long. This is my second and last purchase from this company. Took way to long to receive the first order. Second order is broken.

I would like to pin a different muzzle brake to this barrel, what is the thread size?
also may add a different muzzle brake or is the one that comes with permanently afixed?

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5/8x24

Ordered this with BCG and Charging handle less than 3 weeks ago. Everything works like it should.

Looking to purchase. Just need to know if MD is functional & not just for show.

It says upper assembly is it a build kit or preassembled

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Upper is assembled