Thanks for your interest in my research on the muzzleflash produced by pistols. I believe this is significant, as high muzzleflash can interfere with night vision. Earlier research by the Phoenix Police Department can be found here… http://findarticles.com/p/articles/mi_m0BTT/is_190_31/ai_n27380935/All these loads were shot from my Glock model 20SF in 10mm Auto with 5.15" barrel or my Glock model 32 in 357SIG with 4.5" barrel. The fotografy was done with a Canon 5D and 24-105mm L-series lens. Lens was set at F4, length at 105mm, shutter speed 3 seconds, ISO rating 800, distance 10 feet. These were shot at night in the Arizona high desert; the moon was shining in some shots. Developing in Photoshop included only a Levels adjustment increasing the mid levels a bit (and the same for each shot). Reloads with Accurate #7 and 9 were shot in the 357 but are not included, since the results were the same as with the 10mm. I shot 3 samples of each load and selected the middling pic of the trio. Only the load using Universal and the Winchester factory 357 load showed significant variance among the three samples. Here are my preliminary thoughts that apply only to the powders and loads I tested. 800-X, Accurate #5, and Longshot are unsuitable for Personal-Defense cartridges; the muzzleflash (MF) from these cartridges is quite large and bright and reduces night vision for minutes. Accurate #7, SR4756, Super Field, and Universal seem to be tied for lowest MF, but Universal exhibited significant variation among the 3 samples I tested. Accurate #9 exhibited slightly greater MF than did #7 and Super Field.