M&P 300 Barrel thread size?

[Fayeilding]

So 5.56 is always 1/2x28. 300 blackouts are usually 5/8x24, but can sometimes be 1/2x28.

I am changing stock flash hider and wanted to see if anyone knows the thread on the M&P 15 300 blackout/whisper?

Thank you

 

[vipermd]

5/8 X 24. I have never seen a 1/2 X 28 on 30 cal barrel. Be Safe,

 

[Fayeilding]

5/8 X 24. I have never seen a 1/2 X 28 on 30 cal barrel. Be Safe,

Rare, but some are. Suppressor shopping is how I discovered that, just wanted to make sure, though I figured it 5/8x24.

Thank you, for your help!

 

[vipermd]

I checked all my 30 cal barrels, all are 5/8 X 24. I also checked S&W site and it stated that SW MP 15 300 AAC was 5/8 X 24. I did receive a 30 cal suppressor, that I went to test. I was using a 220 sub sonic 300 BO, I fired one shot, and there was nothing on the target, the rifle shoots one big hole at 100 yds, this was at 50 yds. I opened the bolt, case appeared fine, I took off the can, and end cap, the bullet was spread throughout the can. I checked can, SN, end caps, all were 30 cal, but it was built with 223 inards?? All it did was slight indentation in first iconel baffle. The company replaced it free of charge. I am glad that is was not a 300 win mag. Be Safe,