Home Forums Hunting & Shooting Long Range Hunting How to get velocity without Chrony????

numbchuck, that says more about your very limited mental capacity than anything...what happens at the target trumps all if you've a clue

but you don't

Most published BC figures are approximate. Bryan Litz's book Applied Ballistics (www.appliedballisticsllc.com) has the most accurate figures, from actual firing at various velocities.

The cheaper chronographs may or may not give accurate results. Actual firing at various ranges is the only way to find out where bullets land at different ranges.

JB, I think you just gave an idea for an article on chronographs. On the reliablity of velocity numbers and the amount of deviation a chrono may have.

Oh Froggy you weak minded little twit, still trying to act like Big Stick but cant pull it off

ooh, that stings, runt.

or not. laffin'

I just returned from a long-range precision class put on by Frank Proctor of wayofthegun.us in Lincoln AL. Prior to going, I had loaded several hundred .308's using Federal GMM brass, 168-grain Nosler BTHP's, and 46.0 grains of Varget. I fired five over my RCBS chronograph and they averaged 2740 fps. The Nosler's book BC is .462.

Within the first 30 minutes of range time, Frank had us establish a perfect zero at 100 yards. We then gave him our book BC values (or he assigned a number from memory if we didn't know) and we guessed at a muzzle velocity (I already knew mine, but the rest made educated guesses as 4 of the 5 of us were shooting handloads). He ran the numbers in his ballistics app on his cell phone and gave us the predicted elevation for 685 yards. He had a target berm at that distance and had spread out an array of clay pigeons on the berm. We then went one at a time and held on the upper left clay while Frank watched the shot through his Leupold spotting scope with mill dots. (At that range you can easily see the vapor trail as the bullet is "lobbed" onto the berm and can clearly spot the point of impact in the dirt). Frank would measure the exact drop through the scope and walk us on target as we fine-tuned our elevation setting. Once we either broke the clay or hit on either side of it (we had a slight variable side wind), we recorded our exact elevation setting. Frank then re-ran the numbers through his app (I believe it was Shoot, but I'm not 100% certain on that) and gave us our calculated muzzle velocity. In my case, I had chronographed my ammo in Ohio in about the same temperature and at the same elevation as we were shooting in Alabama, and had a measured velocity of 2740. His calculated velocity was 2725. We then filled out our range cards using data from his app, and then shot at steel plates at 215, 330, 420, 550, 685, and 710. Occasionally we had to hold into the wind on one side or the other, but the elevation dope was spot on.

According to Frank (who is/was a sniper instructor in Army Special Forces), calculating velocity with this method is only accurate at very long range when the bullet has really slowed down and is sharply dropping. In fact, my particular scope did not have enough elevation to get out to 685, so we initially tried his method with my rifle at 420. I fiddled with the elevation setting until I was ringing the 6" gong like the bells of St. Mary's. When Frank put my elevation in, he calculated a velocity of 2950 or so. I have a 26" barrel, but my load of Varget is a compressed load (making an overcharge virtually impossible), and while it is a book maximum, I had safely worked up from below and I knew there was no way they were going that fast, as the Nosler manual gives a velocity of 2700 something and I had clocked them at 2740. We then repeated it at 685 and I used the lower duplex in my scope as an aiming point (which took my maximum elevation from 13.5 MOA to 18.5) and I broke the clay with my first shot. Using that elevation then gave us the calculated velocity of 2725. So, his method appeared to be very accurate at 685, but not so much at 420, just as he had said.

Greg Perry

Where have we heard this before? Hmmmmm...

LO F'ing L !

Yep, rcamuglia, you are right on.

I am no long range expert, but I can testify that the approach you described in your posts definitely works. Frank's ballistic app captured the atmospheric data from the closest weather station, so we didn't have to worry about that too much. There is no evidence quite as convincing as real-world hits, and it was satisfying to know that my book-estimated BC value and my $150 chronograph pretty much agreed with what I could actually see and hear.

As you said, the proof is in the shooting.

The OP wanted to know how to get the velocity of his load without using a chronograph. If atmospheric data is correct (from a local weather station or from a Kestrel at your location) and BC and estimated velocity of the bullet is input into a reputable ballistic program then shot for real world confirmation, the velocity input to the program can be adjusted so that real world drop data will match the output drop data of the ballistic program

The ballistic program velocity number that works matching real world drop data is more reliable than a 50$ chronograph says.

I do this with every load I develop for myself or for someone else.

In the big picture velocity is meaningless (unless it is outside acceptable parameters for the cartridge/bullet combo). What matters is having reliable drop data that gives you first round hits

This will work.

Yep. I actually prefer to tweak my BC and velocity to match actual drop date than use a manufacturers BC and even a good chronos readings. The only real problem with this method is you are at the mercy of your scope manufacturer. If your clicks do not truly reflect 1/4 MOA or whatever is given you can be a mite off when your environment changes.

I have a chronograph, but it still takes real trigger time to compare hits to computer generated drop data.

Much like folks that put SO damn much emphasis on low SD/ES... doesn't matter if it won't group.

You have to shoot it at the ranges you'll use it. I would NOT EVER trust blind data from calcs....

I'm going to be perfectly honest and state that for the last 3-4 loads that I've shot past 500 yards, I didn't use a chrony to determine the velocity on them.

WOW this post (thread etc.)went in the wrong direction from the start.......HOW TO CHEAT AND MAKE THING'S EASY !!!!!!!!!!!!! (Obama factor).

To get an accurate velocity and SD/ES.... you need a real chronograph (not a chrony!!!!!)and do true load developement

Lets see what reason would I have for accurate velocity? To plug it into a ballistics program is about the only need I have. I do not need to know SD/ES if I have no vertical dispersion at long range. IMO what I can learn and implement from actually shooting and collecting data trumps what I can learn from a chronograph any day.

Shoot a target at 100 yards..count the seconds it takes for the bullet to hit the target...ie 0.125 seconds....divide 300 feet by .125 seconds...velocity = 2400 fps.

......or just buy a good one and trust it.

No offense meant. I'm just bored today.

It works! I just tried it and my SD and ES went way down!

for most, the object is not to see how hard we can make this schitt, but i suppose some people may think obcessing over minutiae will give the same results as actually shooting at long range...

i guess it is also 'cheating' to work up a load in ten rounds or less instead of doin' multiple ladders looking for nodes and schitt.

Uh, ..yes?

I guess....



But I could be wrong IME