Velocity

truenorth777

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anyone know the formula for figuring bullet velocity between two different ranges?
i think i read it's in the Apllied Ballistics software. not sure.
 
Do you mean the bullet drop at 2 different distances?

i read that if you shoot at two different [known] distances, and measure the drop between the two, there's a formula for calculating muzzle velocity, that according to bryan litz is quite accurate..
 
It's called "truing" the ballistic calculator. I believe the Horus Atrag software can do this. I'm sure other calculators can too.
 
It's called "truing" the ballistic calculator. I believe the Horus Atrag software can do this. I'm sure other calculators can too.

yes, that is what i've come across too, but i thought it was the Applied Ballistics app.
but i've read there is a formula you can use to do that, independant of software/PDA's/smartphones.
just wondering if anyone has come across it anywhere, or has experience comparing it to the software or a chronograph for verification.
 
i read that if you shoot at two different [known] distances, and measure the drop between the two, there's a formula for calculating muzzle velocity, that according to bryan litz is quite accurate..

Actually this method is very sensitive to small errors made in measuring either the bullet drops or the distances.

If you want to know your velocity, you are much better off to measure it directly.
 
Yeah it's too complicated to do long hand. You'd need to fill in a lot of variables that you probably don't have. With out that you could be hundreds of FPS off

Something I've done when forgetting my chrony, put all of my weather info into my iPhone app, correct the scope to bore measurement, and play with the velocities until the trajectory works out.

Edit: Not sure if it helps but this is a site I had saved from when a friend and I were monkeying around with cannons.

ht tp://hyperphysics.phy-astr.gsu.edu/hbase/traj.html
 
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thanks guys. i'm pretty sure it was something as simple as:
take a shot at two known distances, like 100 yrds. and 200 yrds., measure the drop in POI.
the formula supposedly figures out muzzle velocity from there.
not sure what other variables are required, like B.C., bullet weight, etc.
wish i'd been paying more attention and could remember where i heard it or read it.
 
thanks guys. i'm pretty sure it was something as simple as:
take a shot at two known distances, like 100 yrds. and 200 yrds., measure the drop in POI.
the formula supposedly figures out muzzle velocity from there.
not sure what other variables are required, like B.C., bullet weight, etc.
wish i'd been paying more attention and could remember where i heard it or read it.

D*(G/2*H)^1/2?
D= distance from muzzle to target
G = gravity 32.15 ft/s/s or 9.8 m/s/s
H = measured drop

So 100yds and 1" drop from a zero degree angled barrel= 300 ft, so 300*(32.15/2*.0833)^1/2
300*(13.91).....300*13.91=4173

Will that help you get started?
 
D*(G/2*H)^1/2?
D= distance from muzzle to target
G = gravity 32.15 ft/s/s or 9.8 m/s/s
H = measured drop

So 100yds and 1" drop from a zero degree angled barrel= 300 ft, so 300*(32.15/2*.0833)^1/2
300*(13.91).....300*13.91=4173

Will that help you get started?


thanks, but dang, my head's spining.
i'll have to chew on that awhile...
 
Just about any Ballistic software can do it if you are patient. Put in all the KNOWN data (Bullet parameters, atmospheric conditions etc). Run the software with what you think the muzzle velocity is. Compare the calculated drops to the actual values and adjust the muzzle velocity in the software and run it again. Keep adjusting/fine tuning the value that you put in for your MV untill the calculated drops match (as close as practical) the actual drops.
 
These formulas can and do work but you need to make sure you have the correct BC of the bullet and your not going to get an accurate measurement with a difference of 100 yards as the accuracy of the rifle and your loads will have too much of a influence on the measurements compared to the small drop distance you are using to calculate it. I have had success using it between 300 and 1000 yards.
 
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