Knowing that Armalite and now DPMS makes the AR in .243 Win, I pose this:

There is much discussion and debate regarding a so called replacement cartridge for the .223.  I know the biggies are currently 6.5 Grendel and 6.8 SPC.  Frankly I think the .243 Win is far superior to all the above for an infantry type cartridge.  

Everybody makes it, ballistics are fantastic.  What say you?

i agree all the way with you!

Quoted: Frankly I think the .243 Win is far superior to all the above for an infantry type cartridge.

That is highly debatable.  Let's start with the fact that the 243 Winchester does not fit in an M16's footprint, and needs an AR10 platform to work.  That right there turns an assault rifle into a 10+ lbs battle rifle.  Then let's add the heavier, longer ammo, which reduces ammo load-out.  Then let's not forget that the 243 Winchester is a major barrel throat burner unless it is loaded with powders far too slow for a gas operated rifle.

The 6.5-08, now the 260 Rem, is my all-time favorite cartridge.  Good ballistics, lethality, wide range of bullet weights, good bbl life, and quite tolerable kick.  I had a custom Rem 700 in this caliber.  (Why, oh why do we sell our guns?!?!?)  It's right on par with the 257 Roberts and 6.5 Swiss, both which have been around awhile.  Just goes to show that we have really plateaued with rifle cartidge performance.  

I'm seriously considering an RRA in 260 this summer.  Magpul PRS Stock, Lilja bbl, Mark 4 scope.  Sytlin'!!!  

Quoted: The 6.5-08, now the 260 Rem, is my all-time favorite cartridge.

+1  

I have a custom NRA Highpower match rifle built on a pre-64 Model 70 action in 260 Rem.  The thing is a hammer and Lapua Scenar 139s (BC = .615) at 2600 buck the wind like nobody's business.

Looks like this:


But 308-based cartridges are simply too large to fit in an M16, and take the rifle from assault rifle to battle rifle.

The 6.8 SPC is the closest to the original proposal for a NATO standard cartridge: the 7X43 British.

Now DO NOT start another 6.8/6.5 firefight.

Swwwwwweeeeeeeeeet rifle!

I looked at building a 243 or 25WSSM in a gas gun but decided against it because of a couple factors. My application is varmint hunting and the 243 has quite a reputation in that arena especially in fur loss.  The other consideration is being held to 6 or 7 rounds in the magazine especially in a pack of wolves. To me that would be offsett somewhat by the use of the much lighter AR15 platform. I was originally concerned about the WSSM pressures in a AR15 but I'm sure there would of been a body bag deal by now it it was a problem. I went with both the 6.8 and Grendel because my hope was the reduced velocity would be more fur friendly than the higher velocity 6mm's. They both have proven high capacity magazines available. My needs are specialized and may not apply to your environment. Don't know how much the magazine capacity/reliablity is a factor if you go with a standard 243 instead of a WSSM but feel the fur issue is the same with comparable velocitys.  If I choose a WWSM gas gun it would be a 6.5 and would have one today if Oly would get off the mark and make a barrel.

UgashikBob i dont know what your talking about the 243 causing fur loss. i hav shot countless deer,pigs, mountain lions, and other animals never EVER EVER had fur loss. 2 of my deer enterted and exited without even bleeding just a .243 hole on each side. and they both dropped on the spot(chest shots).

Quoted: Then let's not forget that the 243 Winchester is a major barrel throat burner unless it is loaded with powders far too slow for a gas operated rifle.

+1 reason it shouldn't be used in Uncle Sam's Arsenal, barrel errosion would be great increased, and cost him losts of $$$ in replacement barrels.   The ideal switch is one that requires exchanging a minimum of components without sacrificing service life of the weapon.