7.5" AR ballistics

[DocGKR]

Check the comments in post #18 of this thread...

[Josh-L]

Thanks Doc I missed that post. Would the Black Hills load with the Barnes bullet be considered barrier blind?

[DocGKR]

Check the second paragraph: http://m4carbine.net/showthread.php?t=19881

[Molon]

i know at extended ranges (past 200yds.) that the projo velocity is marginally slower than the same one from a longer barrel.

False. At 210 yards, Hornady 5.56 TAP fired from a 7.5" barrel is going to have a retained velocity that is more than 600 fps less than the same load fired from a 20" barrel.







...

[NightFighter]

does it drastically change the usefulness and performance if a 7.5" sbr uses 7.62 x 39 ammo? from the little i have been able to read and understand it seems that 7.62 x 39 ammo is a better performer than 5.56 ammo at short distances < 200yds. now i may be completely wrong, but i figured if anyone could set me straight it would be the people on this forum. thanks for reading and replying to this post.

[Molon]

from the little i have been able to read and understand it seems that 7.62 x 39 ammo is a better performer than 5.56 ammo at short distances < 200yds. now i may be completely wrong, but i figured if anyone could set me straight it would be the people on this forum

You are wrong.


courtesy of DocGKR

[tpd223]

correct! the DoD issued 5.56 has to high velocity on close range, it was never designed for CQD!
Using a std issued military round on close range is ineffective! It has a too high velocity to deliver any punch into target!
A hunting round on the other hand has a lower velocity, and is designed to be used on shorter range!

Respectfully sir, your grasp of this subject matter is incorrect.

The military 5.56 ball ammo, generally speaking, works better the faster it goes.

Hunting bullets do not work better because they are going slower, it is because of the design of the bullet.

[NightFighter]

You are wrong.

ok, from my interpertation of the image. the 77 gr 5.56 and 6.8 round do the most damage? if my understanding is correct. thanks for the clarification.

[variablebinary]

Let's not forget the SCAR PDW, and HK416 PDW.

There is a market among military and LEO for super short 5.56 weapons. I don't think there is anything to gain by going so short, personally.

Logistically, it does make sense to use a common weapon platform and ammo for PDW's, instead of an PS90, KAC PDW and HK MP7. These guns and the associated ammo are very expensive, and don't have a support pipeline in place, in the same way an HK416 PDW would.

Then again, does a 5.56 PDW make more sense than an MK18, Colt Commando, HK416 D10RS or CQC SCAR? I say no.

[BAC]

Badly wishing KAC would release their PWD on a lower with XCR/ACR/Bushmaster ambi features... that could be a game-changer in police work, if it works as advertised.


-B