I do not agree!
20/28 powder has the burn rate as stated. Then one can use W 296/h38 minimum charge and the maximum col that will feed in your magazine safely. It wasn't that long ago when most of the 'pistol' powders were shotgun only.. Make a few and try it to see if it will
work your action well. Adjust col and charge carefully until you have a good reliable recipe for your use.
I was fortunate to see information on line that stated he used Unique recipe and the results show a 0.2 reduction would be
perfect. I was able to buy 8 lbs of 20/28 and as soon as I finish my VV N320 I will be working up a load for my purpose.
have to use the powders available. I use 4.0ge N320 with a bayou 225gr tcfp with a col 1.230 (max for my sig with this
bullet profile} crimp .4570, It works very well in my sig 220, sw625.8 and baretta cx4 carbine,
Use care, feel the recoil, see the accuracy, if something is not right, STOP, Pull the bullets, check the powder charge, col,
crimp adjust the powder charge, Enjoy the challenge.
jpl