Hodgdon had 3 "HS" powders, HS-5, HS-6 and HS-7. Of the 3 only HS-6 is still in production. HS-7 was the slowest of the 3 and much more suited for Magnum rounds rather than lower pressure rounds. HS-7 is closer in burn rate to H110 than HS-6 so like said above, not a really good powder for a .38 Special or for that matter the .45 Auto. You will probably like it when used in your .357 Magnum rounds especially with heavier bullets. HS-7 is VERY close to the burn rate of Blue Dot so use Blue Dot as a gauge of what calibers HS-7 will be good for. (not the charge, just the application)
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I have a 1995 Hodgdon load manual with multiple listings for HS-7. If you have a question on a specific caliber just let me know and I'll give you the data. Just remember, just because that powder is listed for a caliber doesn't make it a good choice. It's listed for most of the .38 Special +P loads but then again so is H4227. (which I wouldn't use in a .38 Special either) I currently use HS-6 for my hot .38 Special +P loads but also did so when HS-7 was available.
