Is there a way to calculate Muzzle Velocity?

[repiv]

I do not have a crono yet and would like to know approximately what my velocity is if there is a software that can measure it.

Lapua Brass
CCI BR2 Primer
44.8 gr Varget
178 Amax bullet
Ballistic Coefficient 0.495
Sectional Density 0.268
Remington 5R with 24 inch barrel
2.838 COAL

I suspect its somewhere between 2650 and 2700 fps

Is it possible to calculate approximate velocity with this info?

Thanks

 

[Rob01]

Re: Is there a way to calculate Muzzle Velocity?

You approximation range is about right. I'd guess it's around 2675-2700fps from that factory tube. Run the chart at those speeds and you will be on paper and can adjust.

Log your actual come ups and assuming your scope tracks perfectly you can reverse engineer the speed.

 

[jakermeister]

Re: Is there a way to calculate Muzzle Velocity?

I've been doing mine with targets at a distance. I'll shoot a target at 500yards and enter a velocity in my ballistic calculator (bullet flight IPOD TOUCH) until it matches and then verify at another distance.

 

[vman]

Re: Is there a way to calculate Muzzle Velocity?

repiv keep in that most chronys made for shooters have a margin of error as well, some actually really crappy.

There are a few models that stand out, Oehler being the big one, that are highly accurate and consistent.

If you do have the range, you can always guestimate. Punch in a thereabouts muzzle velocity into a ballistics calc and then assuming that its correct, shoot as best you can over longer distances to verify.

If say... you entered 2650 FPS, and were shooting targets at 200, 300, 400 and 500 yards and you noticed consistently higher points of impact across the board it would be safe to assume your velocity is slightly faster. The opposite would be lower hits and slower MV.

If your hitting low, try using 2700 MV on your ballistics calc. Still hitting low? Then you might be above 2700 FPS

If you do this, and after each you mark each hit so you know which one is which, you just keep altering your MV until you reach your figure.

To be honest I have had a Master Beta Chrony give me unreliable results and have often used a similar method to the above mentioned, to achieve a more reliable MV.

If you have a friend with an Oehler, use it. Just dont shoot it.

 

[Fred_C_Dobbs]

Re: Is there a way to calculate Muzzle Velocity?

If you know BC, you can calculate MV by measuring bullet drop at two known ranges. If you're zeroed @100 yards, you already have one. Use the same POA at a second target at a different distance (the more different, the better) and measure the difference between POA and POI. From that you can calculate MV. I know the manufacturers tend to fudge BCs but that bullet is seeing enough use from professional shooters that someone should have a good real-world number on it.

 

[desertHK]

Re: Is there a way to calculate Muzzle Velocity?

You need known distance, POI and its difference from the calculated POI, most ballistic software will be able to calculate the velocity from that.

 

[repiv]

Re: Is there a way to calculate Muzzle Velocity?

I shot out to 500 yards today and 2650 seems to be about right. Thanks for the input guys.