Long-ish range chambering?

[SksA1]

Ok so my 11.5" AR is awesome so i want to build another but for more long range precision 600+yards paper and gongs

I want to use a 16"-18" 1:7 or 1:10 twist barrel.

What chambering would be my best bet?

1. .308
2. 300 whisper
3. .223?
4. 6.8?

 

[nemesisincanada]

Your mixing cartridges that require different action sizes!

Look at 6.5 Grendel in short action.
Look at 6.5 Creedmoor in long.

 

[mrsmitty]

Yes the 6.5 calibers are good long range cartridges

 

[pbr streetgang]

must be awesome to have a range that gets out that far.

i would go with a 308 AR, I have been out to 500 with my LMT MWS 308 and it was a thing of beauty.

 

[TRG-42]

If you are punching holes in paper, then 6.5 Grendel . I use the Sierra 123 HPBT and Lapua Scenar version

I find I never bother to take my 6.8 SPC out . If I'm goofing around and pounding rounds downrange, then 5.56 . Played around with the 75Gr A-Max ( singe shot only ) , Sierra 69 Gr etc for punching paper . Obviously since I built the Grendel, the novelty of the 5.56 long range has worn off

I don't see the advantage of of 308 in AR platform since we can't hunt / go in the bush with it

 

[fireball]

.308

 

[rivetc78]

I am the only one that said .223???

If you can;t shoot 600 with your AR...stay home.

 

[vondnik]

ar-15 platform would be 6.5 grendel
ar-10 platform would be 260 rem

6.8 spc and 300 wisper are more suitable for "close in" work
308 in the ar-10 is a no brainer
and you can get excellent result with a .223 using a 1/7 twist with 74 gr bthp bullets out of a 20 inch stainless steel match barrel