As I remember it, my friend was shooting Hornady Custom 195 gr spire points as well as some of his own handloads. We were shooting from covered benches at a 300 yd range. My friend was shooting from the bench immediately to my left. I was looking through my scope at my target, just about to squeeze the trigger, when I saw a bright, white flash off to my left. As it was a cloudy day, I actually thought that lightning had just struck very nearby and was kind of startled. Seeing spots, I unbolted my rifle and stood up just as my friend was unbolting his rifle. I and another shooting companion of ours watched him shoot the rest of the five rounds that he had loaded in the rifle's magazine. Each time he fired, a brilliant white fireball backlit the cover under which we were standing. The fireball actually extended back along the barrel, stopping just short of where my friend had placed his hand on the fore end of the stock. The muzzle blast was stout as well and both the flash and muzzle blast were uncomfortable for shooter and bystander alike. After that, my friend experimented with different powders, reduced charges, different bullet weights, etc. He was never able to get the muzzle blast to go away. That was with an M48 that my friend had cut back to about 18". On the other hand, I have built and shot a scout rifle on a '98 action in 7x57 with a 19 1/2" barrel. It has no muzzle blast problem, unless using light bullets with heavy charges of slow burning powder. Even then, the blast and flash are not nearly as obnoxious as my friend's cut down M48 was. As for why an 8x57 with short barrel produces a brilliant fireball and a 7x57 does not, I cannot say for sure. The only thing that I can think of is that it is somehow expansion ratio related. I say that because the 8x57 seems to work best with considerably faster powders than the 7x57. I don't know why, I only know that it is so from personal experience.