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Shootin4fun · June 19, 2010, 12:15 PM

Agreed...You can determine the accuracy of your load by simply shooting it, and as we all know, many factors affect accuracy aside from velocity. But the only way to really know what's happening and perhaps why, is to clock your rounds and inspect your discharged brass. Deeper bullet seating, bullet weight, bullet shape, powder charge, powder type, powder batch, primer type/mfg, all have effects on speed and accuracy. Those are a LOT of variables! The more variables you know, the less you wonder about the reasons for bullet behavior.

Also agreed; that trajectory must be empirically discovered by shooting the same rounds under the same conditions at different distances. I have seen significant variations from published specs using balistic calculators and charts.

However, knowing the velocity can give you a lot of information about the stopping power, expected trajectory, reasons behind your accuracy findings, and a whole lot more when you record and analyze the data.

Its interesting to know your knock down power too! Comparing different cartridges and loads is also enlightening. Gee, I found that some factory .357 Mag (Fiocci 155g XTP) delivered only the same power (energy) as some .40 S&W. Penetration/expansion tests told a different story about potential damage. Guess I could have gone out and shot some living things to do those tests, but that's not very scientific, and not nice to random animals or people that would be the test subjects...and I'd likely go to prison before I ever compiled my results! ;-)

Knowing the stats on any factory ammo can be helpful in choosing the right ones as well. The extreme spread, mean speed, and standard deviation will tell you a lot about an ammo's potential accuracy. Clock a half dozen different .22 LR ammo and you'll see what I mean.

For bows, it is even more important, because the speed variation is much more critical in terms of knock down and penetration power than a rifle. A 300fps difference in a 150gr bullet expected to go 2800fps is much less significant in that regard than a 30 fps difference in a bow that supposed to go 300 fps. At 2500 fps, the 150 is still going all the way through the deer broadside.

Can anyone imagine NASA launching a rocket, and not clocking its speed??

Ever since I got a chrony, I clock rounds every time I make any change, and have found it to be enlightening, thereby reducing head scratching, stress, and wasted $, and just as important, its FUN!

So if you like to reload, and approach it as the science that it is, I think a chrony is mandatory. I waited years to get one, and it was one of the best hundred bucks I spent.

June 19, 2010, 12:15 PM	#18
Shootin4fun Junior Member Join Date: June 19, 2010 Location: Tahoe Posts: 13	Agreed...You can determine the accuracy of your load by simply shooting it, and as we all know, many factors affect accuracy aside from velocity. But the only way to really know what's happening and perhaps why, is to clock your rounds and inspect your discharged brass. Deeper bullet seating, bullet weight, bullet shape, powder charge, powder type, powder batch, primer type/mfg, all have effects on speed and accuracy. Those are a LOT of variables! The more variables you know, the less you wonder about the reasons for bullet behavior. Also agreed; that trajectory must be empirically discovered by shooting the same rounds under the same conditions at different distances. I have seen significant variations from published specs using balistic calculators and charts. However, knowing the velocity can give you a lot of information about the stopping power, expected trajectory, reasons behind your accuracy findings, and a whole lot more when you record and analyze the data. Its interesting to know your knock down power too! Comparing different cartridges and loads is also enlightening. Gee, I found that some factory .357 Mag (Fiocci 155g XTP) delivered only the same power (energy) as some .40 S&W. Penetration/expansion tests told a different story about potential damage. Guess I could have gone out and shot some living things to do those tests, but that's not very scientific, and not nice to random animals or people that would be the test subjects...and I'd likely go to prison before I ever compiled my results! ;-) Knowing the stats on any factory ammo can be helpful in choosing the right ones as well. The extreme spread, mean speed, and standard deviation will tell you a lot about an ammo's potential accuracy. Clock a half dozen different .22 LR ammo and you'll see what I mean. For bows, it is even more important, because the speed variation is much more critical in terms of knock down and penetration power than a rifle. A 300fps difference in a 150gr bullet expected to go 2800fps is much less significant in that regard than a 30 fps difference in a bow that supposed to go 300 fps. At 2500 fps, the 150 is still going all the way through the deer broadside. Can anyone imagine NASA launching a rocket, and not clocking its speed?? Ever since I got a chrony, I clock rounds every time I make any change, and have found it to be enlightening, thereby reducing head scratching, stress, and wasted $, and just as important, its FUN! So if you like to reload, and approach it as the science that it is, I think a chrony is mandatory. I waited years to get one, and it was one of the best hundred bucks I spent.