i've always been intreagued by the idea of the 300 whisper/kkf rounds.  i've been looking at the ballistic figures and have noticed that the .223 and 300 whisper produce virtually the same amount of energy at the muzzle (approx. 12-1300 ft-lbs of energy).

my question, if one was NOT planning to use the 300 whisper as a subsonic load (with a supressor) is there any advantage with that round versus the .223 in either the 55 grain or green tipped 62 grain rounds?

i understand the heavier bullets retain more energy further down range then the .22, but how about performance on varmints or small game animals?  

i'm just trying to decide if its worth getting a 300 whisper/kkf firearm or just stay with the old .223?  any thoughts, suggestion?  thanks, sloth

I can't think of a good reason to go with the wisper. If you want heavy go .308. Even for supressed work, subsonic .223 for CQB gets the job done quite well and is now the prefered rifle cartridge for this purpose.

The various short .30s are more efficient that the parent bottlenecked cases in terms of powder.  If money was that much of an issue to you, though, you would have to shoot an awful lot to recoup the cost of a new upper.

It is my understanding that the short 30s need a pretty fragile bullet to expand at such low velocities, but don't forget the bullet drop.

There are 2 reasons to get a short .30 as far as I am concerned:

1) You are going to suppress it;

2) Just to have one.

Neither is worth it to me, but YMMV.