This is what I was getting with 2nd curtain. They are mostly out of focus, as I was still dialing in the correct power when I realized it just wasn't going to work. That said, I was able to capture the flash every single time with single shot weapons (.357 magnum and 12 gauge shot gun). you may also notice their finger is off the trigger, as their exposure was taken up to a second after they pulled the it.
Here is another shot in truck headlights, but that doesn't work for these rifles either. You have to fire them so fast to capture the muzzle flash that the shooter is in a violent seizure when you get it. I captured the muzzle flash on 1 out of 30 rounds in this clip. Three shells are visible leaving the chamber, so you can get a sense of how fast he was firing. My camera was on full continuous at 1/13 and I got 1 out of 30. The idea is, with a slower shutter speed there is a better chance for the bullet to leave while the shutter is open. Bolt action (single shot) rifles just weren't going to happen at all. I was able to get so many 9mm pistol muzzle flashes (and I have many more) because we practically had infinite ammo, 600 of the rounds were even free. With an AK-47 we were basically shooting quarters, so I would prefer to improve the quality and predictability of those.
I think I can get some really great photographs. I just need to plan ahead with a proper method. The direct flash is pretty harsh, and I don't have a way to move my flash off camera yet. I'll work on fine tuning the artistic side once I get the practical part down. The suggestion of making the gun's trigger fire the flash was interesting. I don't think a sound trigger would work, as the muzzle flash lasts a very short amount of time, and the bullet is traveling double or even tripple the speed of sound in some cases. I would think the delay and shutter lag would be long enough to miss it altogether, but could be wrong.