is there a way to calculate velocity/muzzle energy on a reload other than using a chronograph?

I believe there is software which does this based on load data. I have done an 'estimation' using eskimo.com (JBS-calculations), based on scope hight, range (two points needed) and POI. I have not confirmed the results but further comparisons and deductions seem to be in the same ball park. I would say definately not reliable! I have done some experimenting and have been able to alter peak pressure and velocity quite dramatically without changing powder charge or bulle weight. In short - reducing pressure but bringing it back up with more powder, producing a markedly higher performance. All this means is thyat simply changing your loading technique will change muzzle velocity. but even so, one should be able to get some sort of estimate, base on what goes into the load. Measuring bullet drop requires knowing the ballistic coefficient of the bullet at the velocities expected. In my earlier days of reloading I was able to load to a certain target velocity then subsequently confirm that estimation with a chonogragh. The scary thing is I got it right! And that was before computers and the internet.

quote:

Originally posted by byf42:
is there a way to calculate velocity/muzzle energy on a reload other than using a chronograph?

byf42

You could capture the bullet in a weighted pendulum, measure the backswing and calculate energy, then calculate the velocity. Theoretically. But nobody would do it that way. The pendulum capture method is simply ridiculous. Chronograph is more direct, accurate, faster, easier and also lets you have a bullet flight path.

Yes, there are ways to calculate expected velocity, but there are variables not knowable by the calculator (computer program, most probably nowadays). Among those unknowables are barrel dimensions, smoothness, cleanliness, amount of lube on the bullets, variations in bullet dimensions. See what I mean?

This is why physicists have labs and shooters have chronographs. There is no substitute for empirical data.

Velocity and pressure prediction programs can come close, but the proof of the pudding is in the eating, so they say.

Parts of the preceeding are tongue-in-cheek and I am not responsible if you are offended. If you think I am stupid, it is becasue you did not get the joke. So whatever you liked, I meant. Whatever you didn't like, was my attempt at humor.

Lost Sheep (Larry)

By the way, are you wondering if there is an alternative to a chronograph for making measurements on fired bullets or are you wanting to know velocities before (or instead of) actually loading and firing rounds. The velocity prediction programs are intended for the latter. For the former I know of nothing more effective and practical than the chronograph.

I saw once that adding 1 fps per foot the screen is from the muzzle would put you real close. I don`t remember exactly where I saw it but, the figure has stayed with me.
In the long run it doesn`t matter much for any purpose I can think of that a hunter or target shooter would have. The chrony you have likely varies by close to the same amount or more from the true velocity.

The chronograph is the best way to go but...

If you know the bullet drop over a specified distance and know the bullet's ballistic coefficient, you can use ballistic software to estimate the muzzle velocity.

A couple of big pitfalls in this approach:

1. Published ballistic coefficients are only valid for the atmospheric conditions under which they were calculated.

2. The bigger the groups, the less accurately will one be able to accurately measure bullet drop which can add a lot of error to the velocity calculation.

So yes, one can get an idea of velocity but with significant potential error.

One of the simplest ways is to interpolate your Load in comparison to a few Manuals. Lets say you are using 50gr of StumpBlaster and you look to see what 3 Manuals average for that amount of Powder with the same Bullet weight. And let's say the "Average" Velocity is 2950fps.

Now subtract 150-200fps from that Average and you will normally be real close - 2750-2800fps.

If you muzzle length is different, change your Guesstimated Velocity by 1% for each inch difference. If the Manual firearms had 24" barrels and your rifle has a 26" barrel, increase your Guesstimate by 2%.

Plenty close enough to use the Ballistic Tables to get you on the Paper at distance and you will never have to totally waste your time messing with a chronograph.

Once you get on the Paper, you can create your own Drop Chart, which a person needs to do whether they have wasted time chronographing the Loads or not.

Best of luck to you.

There is no way to ACCURATELY estimate the MV of a given load in a specific rifle other than through the use of a chronograph or a ballistic pendulum. You have to have a KNOWN, valid starting point from which to procedd. As a matter of fact, I often find that my chronograph gives much different velocity readings that I was expecting based on data in SOME reloading manuals.....

My results are generally more comparable to the data published by Lyman and Hornady than many of the others.

No, not really. Yes you can use BC & drop, but it still going to be guess. You can't use published data either. At best, you may be within 100fps. IF that's close enough, then that's close enough. It's one reason I have had chrono of some kind since I started reloading. I want to know, not guess. Pay attentionat the range & if someon is using one, ask if you can run some loads across. I have never turned down anyone, but if they break it , they buy it.

thanks everyone for the replies!

the reason i asked is that i live in illinois, and there are virtually no shooting ranges where i live, so my range time with a rifle has been cut down considerably. oh well, once again, thanks for the replies

In that case.... I built myself a firing tube into which I can place various mediums. The one I like best is furnature padding wool soaked in water. Anyway, this device is made from carbon-steel pipe and is lined with rolled up carpet scraps. It faces straight down and has a thick 4140 disc at the bottom then a layer of sand. THEN there is a 4140 container also filled with sand, over which is a pile of dry wool furnature packing. (Bullets don't usually make it to the sand bucket). I fire through a rubber mouthed neck in the lid. I am working on building a chrono into it. the 'screens' will iether be 'break screen' or audio 'screens' (using microphones). I use this device in my garden shed in the middle of a suburb and no-one can hear a thing!

I have the answer to your question, byf42. Go to www.handloads.com/calc/ and see there a calculator for drop of any round at just about any range, and on another page, the muzzle energy, momentum and Taylor KO Power of just about any load you can figure up. Compare a .204 Ruger (40 gr bullet at 3950 fps) to a .223 Rem (55 gr bullet at 3250 fps). They are quite closely matched, yet worlds apart. It's a fun thing to play with on a Saturday night. The homepage has five or six calculators on it. See it on the right side of the page at www.handloads.com.

quote:

It's a fun thing to play with on a Saturday night.

homebrewer- i can think of a few other things that are more fun to play with on a saturday night, mainly the blonde/brunette/redhead variety...

anyway.. thanks for the link... awesome website and ballistic calculator. that's cool it gives the taylor ko values... always neat to see what they hypothetically will do. i'm going to crack open a hamm's and run some numbers. until next time, have one for me thanks again

simply NO.
my pet 308 load shoots 2420 average out of my buddies remington 7. My sbs mountain averages 2550.

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Hodgon data shows 165 GR. HDY SP Hodgdon H4895 .308" 2.750" 41.0 2525 MV.
I get that out of a 20" barreled steyr. the same load out of a 25.6" HB steyr gave me 2700. conversly out of a PSS the load barely broke 2500.

quote:

Originally posted by ALF:
KSTEPHENS:

I respectfully disagree, Yes you can to within 95% of the actual velocity and closer. The accuracy of the calculation dependent on the quality of the data you use in the calculation.

The problem with calculations is that generally the smaller the bore the greater the effects of small variables that are unaccounted for in simple calculations...... thus in smaller bores more complex or complete calculations are necessary.

In large bore guns and cannons relatively simple calculations where variables are often derived down to pre chosen variability factors or even simply negated, suffice.

Calculation by regression with known or forced valid variables. Otherwise no. Have a formula - I'd like to see that one please....

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There is even more juicy info on Steve's Reloading Pages. Go to http://stevespages.com/page8a.htm and allocate several hours of time. He's got gigazoodles of information on this site. Bookmark it. Visit often. Enjoy, folks!!