Re: Throat erosion and double-based powders.
I have no idea about all this double base, ball, and other stuff eating barrels. My experience is the worst thing on a barrel is shooting it hot. I have seen guys litterally shoot guns to the point the barrel is smoking the gun oil. I believe not shooting a cool barrel is the worst thing a person can do on a barrels life.
I watched one guy ruin a .5" 308 in 200 rounds. He shot 5 shot groups one after the other continually as fast as he could. I have never seen a rifle barrel that hot ever. He was trying to prove that "modern" guns could be shot hot and it would not hurt them. Rifle would not group under 1" after he was done.
I shoot 120 Ballistic Tips out of my 7STW Sendero at 3600fps using RL22. I don't heat it and never shoot more then five rounds from a cool barrel. I have over 1600 documented rounds through it. Still shoots .5 or less for 5. This is my varmint gun and I use it for coyotes at 0 degrees and ground hogs at 90 degrees. I also do not clean until at least 100 rounds are shot through it. Same POI regardless.
Just a couple of my limited experieces.