I've been working up my new 10mm loads with Accurate #5...previously I had been using WW231. I've been using 170 SWC, 180 LRN, and 200 SWC all RCBS molds.
But today with the the RCBS 200 grainer, that I loaded on my Dillon 650....all I can say is wowww!!!! In my TWO 610 revolvers(they are indentical) I fired 30 rounds(3 in one gun 2 in the other). My extreme spread was only 40 fps.....for me any ES lower than 50 fps is great for a pistol round loaded from a progressive press. Check the standard deviation 9.51..thats incredible. This loads chrono's better and specs better than my control round which is Federal 180g Hydra-Shoks.
Unfortunately the 170 and 180 grainers...exhibited more normal behaviour with 7.3g of #5 their ES was 51 adn 40 respectively with SD of 14.4 and 13.0 still very good for a pistol round.
My conclusion is the with the 200g being a very long 10mm round, case was almost completely used with the bullet and powder...making for very very consistent ignition. The 170 and 180 being nearly 1/8 inch shorter left more air space so ignition was not nearly as presice and repeatable.
Just had to post the my data on the 205grainer
Usual disclaimer....you blow yourself up...thats on you.