Greatest 100 yd energy from AR15 action

v35

What cartridge / bullet combination based on 223 brass and the AR15 action and standard magazine will give the greatest 100 yard energy?

dcs shooters

Out of what length barrel [?]

rufe-snow

Supposedly the Coast Guard was all set to put out a contract, for the .50 Beowulf. But it got cancelled.

tsr1965

If it must be a 223 Remington/5.56mm NATO derived case, it would have to be one of the TCU's, either the 6.5mm, or 7mm TCU.

Mobuck

"it would have to be one of the TCU's, either the 6.5mm, or 7mm TCU"

It would require deeper seating of the bullets to fit a standard mag if I read my manuals correctly. With several bullets, I'm having to cut cases back to 43mm to get work-able OAL with my new 6x45mm.
Actual "energy" at only 100 yards I'd expect to come from big bores.

babun

+1 on the big bores.

The 50 Beowulf with a 325 grain bullet at 1950 fps gets about
2,745 ft.lbs.

Hard to imagine a 140 grainer 7mm at about 2400 fps matching it.

Differently not as flat shooting, and after 200 yards or so,
the 6.5/7mm 's will look better.

tsr1965

quote:Originally posted by babun
+1 on the big bores.

The 50 Beowulf with a 325 grain bullet at 1950 fps gets about
2,745 ft.lbs.

Hard to imagine a 140 grainer 7mm at about 2400 fps matching it.

Differently not as flat shooting, and after 200 yards or so,
the 6.5/7mm 's will look better.


Well, if you read the OP's question, he specifically says based on the 223 case. The only thing in common with the 223, the 50 Beowolf has with the 223, is the rim of the head diameter.

On the other hand, cartridges like the 300 Whisper/300 Blackout have a good chance in this arena too. One can actually run a 220 grain SMK along at about 1200 FPS...and it looses very little at 100 yards. It will feed from a standard, no modification AR-15 magazine too.

EDIT 1

quote:For that matter, the .243 wssm has excellent ballistics and it fits in an un modified AR, but again, it is not based on the .223 cartridge.



This is an incorrect statement. In fact tha AR BCG, gas system, and the magazine, all have to be modified. Even the upper receiver itself has to be modified.

Babun, I am in total agreement. There is so much more out there to be had.

Mr. Perfect

For that matter, the .243 wssm has excellent ballistics and it fits in an un modified AR, but again, it is not based on the .223 cartridge.

ETA: what I meant by "unmodified" is that there is no requirement for the lower receiver to be milled or drilled or modified in any way to accommodate the round. I thought it quite obvious that things like bcg and magazine would have to be different.

babun

You are absolutely correct about the .50 being a different case.

Perhaps more info from the OP will give us more choices??

Such as is he just concerned about the bolt head size, oal limits,
availability of factory ammo????

rsnyder55

With the exception of the parent case, I would have said the 458 Socom. Same mags, buffers, etc. Just not the same case as the 5.56.

1KYDSTR

I am going to venture the guess that you already want the 300 BO and are looking for alternatives to it? In that case, you are largely SOL. Unless you wanna throw in the 300 Whisper or .310 Balckoutski, there isn't much to offer up alternative wise. The Blckout runs everything from 110 gr to 150 gr with a carbine gas tube, and everything from there to 240 SMK's with a pistol length tube and / or suppressor. I really think it's what you need to look at if parent case has to be 5.56?
i should have added that the 130 gr Barnes TTSX has given me the best terminal results at 100 years of anything I have loaded/tested...mean little number and a deer slayer of the highest order!