Hodgdon HS-6 doesn't have a Winchester twin (different VoluMetric Density), but it is VERY close to the same burn rate as W-540.
HS-7 and W-571
are the same VMD according to Lee data and are adjacent on the burn rate scale, so probably interchangeable. I have not seen much info recently about HS-7, they may be taking it out of circulation.
I have not yet taken many trial loads of HS-6 to the range, so I'm not going to offer any advice. The Hodgdon Reloading site <
http://www.hodgdonreloading.com/data/pistol> should give you the same good information generously supplied by Swifty. HS-6 is fine-grained and measures well.
Kinda true since they killed off 540 that there is no longer a twin. But unfortunately Hodgdons disagrees with you.
https://hodgdon.com/hs-6/HS-6
HS-6 is a fine spherical propellant that has wide application in pistol and shotshell.
In pistol, 9mm, 38 Super, 40 S&W and 10mm Auto are some of the cartridges where HS-6 provides top performance.
In shotshell, HS-6 yields excellent heavy field loadings in 28-, 20-, 12- and 10-gauge.
HS-6 is truly an outstanding spherical propellant and identical to Winchester’s discontinued 540.
