Hi Steve and welcome to the forum.
I have a Target myself, and I have been able to get the speer bullet to stabilize by using a very firm crimp. I don't have the number for it hereat work it's the one for the 375 winchester.
I shoot lasercast 240 grain cast bullets now. They can be pushed to jacketed velocities without significant leading, according to the product info. I've shot them at 1800 fps without a leading problem.
Good luck.