I bought a lyman mold in .270 (150 Grain bullet) and want to load the bullets in my Remington 760 pump. I would like to know if I need to crimp this bullet?

Thanks

As long as the recoil doesn't cause them to move forward in the cases, you're OK without the crimp. Your rifle has a detachable magazine, not tube fed, so no need to worry about bullets getting pushed back into the case with recoil in an tube.

Usually, cast bullets are loaded on the mild or moderate side and a slight crimp is beneficial in offering some initial resistance to allow best propellent combustion.