I've loaded the MagTech bullets using several powders. I only have a KelTec P3AT. For reference, Winchester White Box averages 818fps, and Remington averaged about 840, both with 95g bullets. The supposedly HotHotHot CorBon only averaged 903fps with a 90g bullet, while Speer 90g Gold Dots averaged 875. This is to give you an idea what my microscopic barrel does with various rounds.
With MagTech bullets I've tried Accurate #5, but only got 757fps at the maximum recommended charge of 4.8g, and got some bulged cases to boot. (The KT chamber does NOT fully supportive of the case head.) Universal Clays was even worse in the velocity department - 3.5g gave only 614fps. Note that Universal has about the same burning rate as W231, while #5 is slower and #7 is slower still.
Best velocity was with Accurate #7 - 6.5g gave 826fps average velocity, about equal to the commercial Winchester and Remington loads. (Using #7, I can also approximate the Speer Gold Dot commercial load using their bullets and 6.7g of powder.)