Re: What is the fastest cartridge?
I have read that they have played with necking down BMG's to 30 and 338. The only problem they were having was keeping the bullets together when loaded with max loads. Bullets were coming out in pieces from the muzzle. This was more noticeable with the heavier bullets and the assumption was the twist had to be so tight it was spinning them apart. I think I found that data when I was researching the .338 Lapua.
"Enter through the narrow gate. For wide is the gate and broad is the road that leads to destruction, and many enter through it.  But small is the gate and narrow the road that leads to life, and only a few find it.
If you find your self in a fair fight, your tactics suck!- Marine 1st Sergeant Jim Ryfinger
Friends don't let friends develop canonitis!
arguing over the internet is like the special Olympics....even if you win, you are still...special!