I think that Federal load was using a temp-stabilized non-cannister version of 4064. Or was it flash-minimized? Or both? There was a LONG thread on that here maybe two years ago.
22-inch barrel and semiauto chamber, I *was* getting near-identical velocities AND really-identical POI out to 500 or so with 42.5 4064 and 41.5 of Varget, newer FC cases near-identical in water capacity to LC and Lapua brass.
But my latest post-shortage bottles of 4064 are now giving me 2640 fps instead of 2540-2580. No real trend temperature-wise in my earlier velocity range.
In general and in my experience, 4064 is way less temp/velocity sensitive than my original Service Rifle mainstay, W-W 748. That stuff was proven to be almost exactly 1 fps per 1 degree Fahrenheit temp change IIRC. 4064 is about half that, if not less. For my uses, I deemed it close enough and I wanted a US-made powder to avoid the potential problems of overseas shipping being interrupted. Based on current availability where I live, I made the right call, but for the different reason of Varget being just too *&(*&$^% popular and simply cannot be found. I even considered switching to H-4831 and heavily-compressed loads going for a modest 2580 FPS, but never experimented with it.
