Just happened to be looking through a bunch of old articles I've saved. Here's a quote concerning pressure from Les Greevy's column, Shooting Sportsman, Jan/Feb 01: "According to Dick Quesenberry, product engineer for Alliant Powder, modern intermediate and slow-burning powders generate their peak pressures from 8 to 12 inches up the barrel--not far from where you hold your leading hand."
I don't know anything about Oval or MX, but I know that black and bulk smokeless both supposedly generated their peak pressures very quickly, as do modern fast-burning smokeless powders. But I was surprised to see someone (who should be in a position to know) suggesting that slower-burning powders take that much longer to reach peak pressure.
Going back and looking at Bell's "Finding Out For Myself, Part VI: Smokeless vs Black", it would appear that the above graphs actually date back to a test run by DuPont in 1933. But from Bell's article, his test results also indicated--as shown in the graphs above--that all the powders he tried (FFFG, 7625, Universal Clays, Blue Dot, and Clays) produced their peak pressures quite close to the breech. All, in fact, within the first inch or a bit more. Makes me wonder about the 8-12" quote from the Alliant engineer.
