Calculating bullet speed
- Thread starter Jvoelcker
- Start date
The speeds quoted in most reloading manuals usually relate to a specific bullet, specific brand of brass, specific primer and a specific barrel length.
If you use different bullet, brass or primer, and a different barrel length, then all bets are off., with barrel length being the biggest variable
Cheers
Bruce
If you use different bullet, brass or primer, and a different barrel length, then all bets are off., with barrel length being the biggest variable
Cheers
Bruce
In strelok you have the 'truing' feature. If you zero your rifle at 100m then fire a group at 200m or 300m then measure the drop and input that into strelok truing it will give you your speed. Perhaps not as accurate at measuring speed as a chrony but the bullet won't lie and you'll gather true data rather than mathematical formula.
I don't have access to a chrony and have used this method and although I only shoot out to 300m it works. Admittedly if your going to be going out further then shoot out to the further ranges and you'll gain better data.
Todd Hodnett uses this method to get DOPE for quick referencing rifles and ammunition. He will zero at 100m then shoot out to a long range eg 700m or so enter the data into the pda and then confirm at a closer range like 400m. Works a treat
I don't have access to a chrony and have used this method and although I only shoot out to 300m it works. Admittedly if your going to be going out further then shoot out to the further ranges and you'll gain better data.
Todd Hodnett uses this method to get DOPE for quick referencing rifles and ammunition. He will zero at 100m then shoot out to a long range eg 700m or so enter the data into the pda and then confirm at a closer range like 400m. Works a treat
Maybe some can, haven't tried them all and haven't tried to do that with any of them...but with any of the basic ones like BulletDrop and etc. you could just keep upping the velocity until the calculated arc matches your real world results.
Alan
palmer_mike
Well-Known Member
Chronys aren’t that expensive, get one or borrow one and then you won’t have to guess........
You'd be better served to spend your money on a chronograph and use free ballistic apps. You're going at at it bass ackwards.~Muir
I am sure there would be someone in your locality who could let you put a shot or two over their chronograph. If not, and when this lockdown is over, I would happily drop in with my Magnetospeed next time I am passing. Would take about 10 minutes to give you some proper information.
I don't see finding out the velocity as being a difficult process...but it would be by trial and error rather than calculation.
Fill in the known parameters in any ballistic app. like scope height, zero distance, bullet weight and BC and a just pop in a guess for velocity and see how it compares with your field results...increase or decrease the velocity until it is somewhere handy.
It might take half a dozen trials but hardly onerous.
Out of interest why do you want to find out the velocity?
I realise that once you have found a trajectory that matches your field results you can use it to extrapolate to other distances...knowing the actual velocity would just be an incidental almost.
If you post your field measured drops and the above details and I am sure some idle person will pop them in to their favourite ballistic app....allegedly.
Alan
Fill in the known parameters in any ballistic app. like scope height, zero distance, bullet weight and BC and a just pop in a guess for velocity and see how it compares with your field results...increase or decrease the velocity until it is somewhere handy.
It might take half a dozen trials but hardly onerous.
Out of interest why do you want to find out the velocity?
I realise that once you have found a trajectory that matches your field results you can use it to extrapolate to other distances...knowing the actual velocity would just be an incidental almost.
If you post your field measured drops and the above details and I am sure some idle person will pop them in to their favourite ballistic app....allegedly.
Alan
Last edited:
I don't have a chronograph but I find I can get decent velocity estimates by noting the amount of bullet drop I have to dial for a particular bullet at a series of distances (e.g., 300yds, 600yds and 900yds). I then fiddle with the muzzle velocity setting for the same bullet on this website Ballistic Calculator GunData.org until the trajectory matches my real life bullet drop values at those distances. That gives me a nice estimate of the real life muzzle velocity. I have verified my velocity estimates in my .308 by shooting standard NATO 7.62x51 ammo which is of known velocity and matching the bullet drop values to those shown on the website. That shows my velocity estimates are within about 20fps of the real velocity.
palmer_mike
Well-Known Member
Where are you based? Can’t get cheaper than borrowing one!
Jvoelcker
Well-Known Member
My 243 rounds are reloaded but checking against tables has proved not that accurate.
I'll invest in a chrono to see what I'm actually getting
Similar threads
