Not really sure why you'd need "more power". I think we talked about this previously, but I have a brand new GAP .223 Rem bolt gun I had specifically designed to shoot the 90 VLDs in 1000 yd F-TR competitions. I've only done very preliminary load development, but I believe I will end up very close to 2850-2860 fps from a 30" barrel shooting the 90s with H4895. Other than the barrel length, the only thing that would really be considered unusual about this rifle would be the freebore, which is quite long. COAL for the 90 load is in the neighborhood of 2.65", so it's single feed only. Also, because of the extremely long freebore, it's really not an option to load anything else. So a rifle really optimized for the 90s is pretty much limited to those. However, I fully expect this rifle with the 90 VLDs to keep pace with my 30" barreled .308 and 185 Juggernaut load at 2770 fps out to 1000 yd.
How much more is really necessary? I guess a lot depends on exactly what you want to do with it. Shooting the 90s out to 1000 yd is really pushing the limit of the .223, even with the improved chamber versions. Most of the people I've talked with have indicated that at 1000 yd, the 80-somethings are simply not going to be optimal, even if you get them going 3000+ fps. Yes they will get there, but they're not going to keep pace with a decent .308 load using a high BC bullet like the Juggernaut, not by a long shot. I know that many have and will continue to shoot 80 gr .223 bullets to 1000 yd, or even slightly farther, but you will likely be giving up in the neighborhood of 1.0 to 1.5 MOA of windage to a 90 VLD going 2850 fps, which is considerable. The improved .223 chamber might buy you a little bit extra, but it's not going to be day and night better. The BC of the bullet you choose will likely far outweigh slight gains from increased charge weight. Unfortunately, the difference in length between the 80s and 90s is large enough that a chamber that allows you to shoot both will not be optimal for the 90s. It may work ok, but you'll be giving away some of the gain that came from the improved case volume.
My thought would be that if the specs of the 90s are insufficient, you'd probably be better off in the long run going with a different caliber that had better ballistics. There are certainly others that would give better performance while still having minimal recoil. I went this route because I wanted to shoot it in F-TR, which stipulates an unmodified .223 Rem chamber. I knew in advance that I would need to go the extra mile with regard to brass prep and reloading, and have to chase the lands fairly often as the 90s are best seated at touching + ~.010". But if you don't need to do that for a specific reason, a 6BR (or similar) ought to do everything a modified .223 will do and more. Alternatively, if you don't want the extra trouble associated with loading the 90s and a rifle optimized for just that bullet, maybe an "improved" chamber set up specifically for the 80s will allow you to do what you want with a little less than a 30" barrel. Anyhow, just a thought.
