finding fps without chrono

[tmckay2]

is there a good, reliable way to do this? can someone explain in detail? i want to figure out some trajectories. thanks

[Irving]

Do you have a stop watch?

[Hoser]

One way is to zero your rifle at 100. Then shoot a few rounds as far away as you can.

Plug the data into a program until your muzzle velocity starts matching up with your drop.

Not a good way to do it, but it give you a rough idea.

[BigBear]

Between this and the USPDA state championship thread...


What is the purpose of chrono'ing and why is there a limit? Wouldn't a faster fps result in more damage to target and thus less chance of survival?... unless the bullet travels so quickly that it punctures and carterizes... but I doubt that would happen at even super speed!

Can someone explain it all to me?

[SA Friday]

Between this and the USPDA state championship thread...


What is the purpose of chrono'ing and why is there a limit? Wouldn't a faster fps result in more damage to target and thus less chance of survival?... unless the bullet travels so quickly that it punctures and carterizes... but I doubt that would happen at even super speed!

Can someone explain it all to me?

Chronographing the round gives you the bullet's velocity. Multiply the velocity and the bullet weight then divide by 1000 and this gives you a comparible measurement of momentum (power factor). For every action, there is an equal and opposite action; so that measurement of momentum is quantifiable to the pistol's recoil. The hotter the load, the more the recoil. This levels the playing field as USPSA regulates a momentum "floor" for minor and major power factors. You shoot less recoil, you get less points for off-center hits. Minor is 125pf minimum and major is 165pf minimum. There is no ceiling in MOST pistol competitions (just don't show up shooting 50 AE). The hottest I've seen was 209pf from a Glock 45 GAP. It was on the fringe of scary to watch the guy shoot it.

Some matches set a ceiling on pf and ammo types to stop the steel targets from getting all chewed up. For example, a 160gr 7mm Nosler Partition wil cut through 3/8" AR500 plate like butter at 600 yds. It leaves an impressive quarter sized hole clean through the plate. This sucks, BTW, if you own the plate.

[BigBear]

Ah... that all makes sense... but I'm going to have to ask (I think I know the answer, just want to clarify/make sure): What should I NOT show up shooting a .50AE? Disregarding the ceiling limits, wouldn't the power factor give that shooter an edge? Or is that why there are time limits to equal out teh power levels?....