re: A rule of thumb on changing point of impact on fixed sighted guns

quote:

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Slower rounds shoot higher.

Faster rounds shoot lower.


ETA: For identical projectiles.

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This statement is true. Like weagle99, I've always heard it said that this occurs because recoil of the slower moving load has caused the barrel to move slightly upwards in recoil before the slower velocity round has exited the barrel. That may not be the exact reason, but I've yet to hear of a better alternative explanation. I'm not surprised if there's not a video out there to demonstrate this. The movement of the barrel need be very minuscule to affect the point of impact. I'd think it would take very special equipment to demonstrate this.

I hate to muddy the water, especially since I've defended the original post, but under some circumstances, the round's muzzle velocity can nullify the original statement. For example, I shoot a lot of high velocity, rifle type cartridges (i.e. 223 Remington, 7-08 and 308 Win to name a few) in long barreled specialty pistols like the Thompson/Center Contender and Remington XP-100. In these situations, the higher velocity round has a higher point of impact than does the lower velocity round.

Nevertheless, weagle99 points out an interesting fact that's not known to many.