SW Precision is renamed Lovex SO62, a Czech manufactured powder which has been widely available across Europe for many years. If you have QuickLOAD, simply use it with SO62, the entire Lovex range being in the program and the default values pretty accurate IME. In small cartridges like the BR and Grendel, QuickLOAD gives it near identical (Pressure / MV) results to VarGet and suggests in turn that they're a tad faster burning than original IMR-4064.
Until Western Powders bought the Accurate Arms Company some 15 or so years ago, SO62 was sold in the US as Accurate Arms 4064, an accurate (pun unintended) description as AAC-4064 and IMR-4064 are close in their characteristics and behaviours. (Today's Accurate-4064 from Western is made by General Dynamics Valleyfield in Canada the maker of most IMR powders, and although similar is not the same thing as the Lovex / SW version.)
one possible issue with 'Precision' / SO62 in the BRs and BR based numbers is kernel sizes / density. Like original 4064, it is a 'log powder' and moreover often has some very long kernels in its make-up. Another live thread on this forum about SW powders complains of this feature - both in lack of uniformity and problems with powder measures and dispensers. Irrespective of burning speed or other characteristics, kernel sizes may see charges take up more room than same weights from the very short-cut (and regular) VarGet.
I've used this powder in many applications where IMR-4064 and VarGet are staples and had excellent results, but never any member of the BR family to date.