hey rufous,
have a 22250 ack. with 7 twist,shoots berger and jlk 80 gr. extremely well,also does well with jlk 90 gr.. really don't need 7 twist for 80s. rpm's get to be a problem when over 3500 fps. still when you slow down a bit they work extremely well. for some reason seem to be able to push jlk faster than berger, before rpm gets them. if i was going to do it again probably go with 22br, or 22ppc.
My rifle is a 1-8 twist, which is what Berger recommends for that bullet at 22-250 velocities. If I were shooting it in a 223 I would definitely go to a 1-7 twist barrel.
Like Bruce, I like Berger VLDs. I shoot them in my AR-15 service rifle from 200-600 yards. 70 gr VLDs for 2-300 rapid fire & 80s for 5-600. The 70s do tolerate jump well seated at magazine length. Both have provided me with some very high scores (when I do my part, which is rare enough
).
The rifle is a Colt receiver with a 1:7.8" Obermeyer 20" service rifle barrel & iron sights, built by Bill Wylde. JLK does make a 90 gr VLD that has a good reputation, but I've not shot any.
Powell River Laboratory makes a dense alloy VLD the same size & basic shape as a Sierra 80, but the super dense core brings its weight up to 107 gr! They don't normally sell to the general public (I asked).