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how far can you keep a 300 Blkout supersonic?

Blasst

Sergeant
Full Member
Minuteman
I bought a shorty 10" when they first came out and I have been curious now that I am seeing 16 & 18" barrels if anyone has worked up a load & high bc bullet and chrono'd it out at 800 or 1000. I'm guessing maybe out to 800 yds they may stay supersonic. Anybody been playing with it?
 
Considering that the .308, at some altitudes is tough to keep supersonic to 900, I don’t think there’s any way you’re going to keep a .300 BO supersonic to 800. First and foremost, that’s NOT what the round is built for. Secondly, as stated above....WHY ??

The short answer is: No, I seriously doubt one could do it.
 
well with Frank recently taking a 308 out past 1400 using Warner tool flat line bullets it kinda changed the playground we have been accustomed to.....essentially giving a 308, 6.5 ballistics. And then he took the 6.5 out to 1700 if I remember correctly. But these are expensive solids made on a lathe, meant for competition not plinking. But still nice to see the envelope pushed when we thought we had milked the good old 308 as much as possible, suddenly monolithic solids break new ground. I doubt Warner Tool is messing with the 300blkt. I'll have to check.
 
As you say 'competition not plinking'...I am not aware of any 300 blk long range competitions, if there is no market, doubt there will be product. But anything is possible if you have the money. Good luck...I love the 300 but it is a novelty caliber and fun to shoot.
 
300 BLK = American 7.62x39. Ballistics are nearly identical. If you want something for 800 to 1000 yards, stick with the .308/ x51 or .300 Win Mag. If the intent is to have a round with that performance out of an AR15 platform, look at a 6.5 Grendel.
 
Maybe try some Lapua based BO brass loaded to the gills on the verge of popping primers, with some of those 160gr Flatlines?? I bet most would be surprised what it would do..??
 
If 2050fps would be possible, the 155gr Flat line would be supersonic to just under 800yds at sea level fwiw
 
6.5 Grendel would be a much better choice for the AR-15 platform at those distances.
 
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.223 would be a much better choice for the AR-15 platform at those distances.

Fixed that for you. Though Grendel, 6AR, HAGAR, etc. are indeed much better LR options than Blackout as well.
 
my 10.5" 300 blk is super accurate with 125TMK and 18.6g H110. I have zero issues banging steel 5 for 5 at 500M. Chrono at 2100. I only shoot supers suppressed

 
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While that is obviously a very accurate rifle, at 500 yards your within 50-100 yards of going transonic. The OP was talking about 800-1000 yard shot. Is it possible? Sure. Is it the best tool for the job? Not even close.

Assuming a 100 yard zero, your holdover at 1000 yards would be over 70 FEET! Nevermind the fact that a 10mph crosswind just moved your bullet over roughly 16 FEET!

Out of all the cartridges available for the AR-15 platform there's few that would be worse choice than the 300blk. I have two 300blk rifles, but they will likely never be shot past 200 yards.