Th efiner, FFFg powder has more surface area per grain of weight, so burns faster and produces higher pressures, quicker. It also produces a sharper felt recoil force that some shooters don't like. The argument in favor of using FFFg loads is that with the faster rate of burn, the ball upsets and fills the grooves to seal the ball better, giving better velocity and accuracy. I don't see that those loads give more consistent velocity readings on the chronograph, at least with my testing, so I am still undecided on that claim. Some guns do seem to shoot FFFg loads better than FFg loads, even making up for the difference in velocity by decreasing the amount of FFFg powder used compared to FFg, or vice versa. It is important to find the " Sweet spot " in the range of velocity that your particular barrel likes the best. The nice thing about having and using a chronograph is that you can find the sweet spot much faster, and when changing powders or other components, simply adjust you powder charge to give the same velocity to get that " Sweet spot" again. The Sweet Spot " is the velocity that gives the lowset SDV reading, and which seems to shoot the smallest groups, off-hand, or off the bench, or cross sticks.
Changing brands of balls, or patches, or patch thickness, or even lubes, and brands of powder, or even the lot of powder can change the velocity enough to miss the " sweet spot ". The reason the bench rest shooters, and the Chunk Gun shooters spend so much time measuring everything is that they know, even with the massive barrels they shoot, that everything "MATTERS" when you are trying to get the most accuracy at the longest ranges. The same concerns affect shorter ranged hunting guns, even when the shooter does not need nor demand a high level of accuracy to kill a deer. Most hunters don't want to needlessly wound an animal, and virtually all hunters don't want to MISS an animal when hunting with a one shot gun like MLers. That is why we practice shooting until the gun feels like its attached to your body, and is an extension of your brain. And that is why we try to find that sweet spot. Once found, we want to stay there.
If you find a load using FFg powder that seems to work for you, stick with it. But, if you have it, also try a FFFg powder load that gives you the same velocity to see if the barrel does not like it even better. I had a friend who tried every load he could think of, changing components, and actually bruising his shoulder after firing hundreds of round out of his new .62 cal. rifle. Then, on someone's suggestion, he tried FFFg powder in the gun. He found his " sweet spot " rather quickly, and was in shock. He had been the guy in the club that preached using FFg for everything larger than .50 caliber. He would get in big arguments with anyone who dared use FFFg in a .50, .54, or .58. Many of the guys had been using FFFg load in their rifles for years, so he was quite a sight to see arguing with them. He admitted he felt really silly after his experience with his .62, and asked me if He should find all those guys and apologize to them. I told him I would write him up in the club newsletter and mention his apology to everyone. That seemed to work well for everyone. I got a couple of phone calls about that one from some of the guys who were apparently angry at my friend over this. When they read my story about his journey to discovery, they laughed, and called to tell me so.
