Estimating velocity

[SteveS]

I don't have access to a chronograph so I just kind of guess/estimate the velocity of my handloads. I've been good with that.

The thing is, I've been loading my 4" Ruger Security Six with 5.5 grains of Red Dot under a 158 grain boolit and figuring I'm getting about 1000 fps. The reason I've been thinking that is a guy who has a chronograph told me he was getting 1000 fps from his 6.5" Blackhawk with 5 grains of Red Dot.

Today I was shooting with I guy who insisted I was probably getting around 1200 fps with my load. This guy is a long time handloader and normally I would take his word for it but this seems like to big of a discrepancy to me.

So my question is, is there any way that is fairly accurate for estimating the velocity of a load or is a chronograph the only tool for this?

[Yodogsandman]

The only good way to guestimate is by going by a manual for your exact load and gun barrel length. Otherwise you need a chronograph.

[sdcitizen]

I suppose if you were shooting steel plates at a known distance (at least 50 yards) and had a shot timer that would pick up the impact on steel, you could calculate it...It is also easily possible to have 2 chronographs that would read that far apart, though one of them would be a bit out of calibration. I believe that the normal error rate is around 3%, so 2 chronos that both pass could theoretically read 60fps different at 1000fps. 1200 does sound high in my estimation though.

[runfiverun]

you could do it the old school way and hang a log on a rope and shoot into the end of it.
the amount the log swings will give you your energy you can do the math using your boolit weight to back track the velocity from that figure.
the numbers [and blue-prints] come as a supplement in the p.o. Ackley manuals.
of course for another 35 bucks you could buy a chronograph and know for sure.
but that would take all the fun out of it and you wouldn't have parkers books.

[DrCaveman]

When im working a load that hovers around the transsonic region (1130 fps) i often hear very different reports from shots within the same cylinder

It worried me until i realized i was dancing around that range. I think it is why most great loads fly below 1000 fps or go up around 1200+. Not generally good for things to pass the sonic threshold in flight.

I definitely hear a solid rifle-crack shooting my 1400 fps 44 mag loads while the same boolit in front of a modest charge of fast powder (estimated at about 1000 fps...10" barrel) makes probably a quarter the noise. It seems more noticable to bystanders than the one pulling the trigger, in my experience.

[Mr opinionated]

I do not do a lot of posting here but i do read a lot here so to answer your question estimating velocity this is what i use don't remember where i got it but it does work some what close for estimating loads velocity that your are working up but remember there is a still a lot of variables to deal with

Here the formula i use


grains used (estimated grains)
--------------------------------- X known velocity (a quality manual) = estimated velocity
know grains (a quality manual)

5.0 red dot (estimated)
--------------------------------- X 1215 FPS known =1104.55 FPS estimated
5.5 red dot (known grains)



those known grain amounts and velocity number came from lee #2 manual this will get you some what close 100 to 200 FPS + or -

I am sure somebody will say this formula does not work but i know better


MR.O

[SteveS]

Thanks guys. From the info I've been getting, I think the load is a little hotter than I thought and the 1200fps number probably isn't out of the question.

Well, what good is a hobby if it doesn't drain your checkbook, right? lol

I think there might be a chronograph in my future.

Is knowing actual velocity really worth the $100 or so that a chronograph costs? I'm going to have to give it a little thought.

[mongoose33]

Thanks guys. From the info I've been getting, I think the load is a little hotter than I thought and the 1200fps number probably isn't out of the question.

Well, what good is a hobby if it doesn't drain your checkbook, right? lol

I think there might be a chronograph in my future.

Is knowing actual velocity really worth the $100 or so that a chronograph costs? I'm going to have to give it a little thought.

In my occupation I do a lot of measurement and statistics. A scientist, don't ya know. :)

I cannot--but this is just me, my background pretty much guarantees it--imagine handloading without a chronograph to give me absolute verification of what I am producing w/ handloads. Oh, sure, the manuals should give me some idea where I am in velocity, but even then, to match the manuals you have to use the same equipment--and that you almost certainly do not have.

Further, I typically chrono 10-shot strings. If I'm using range brass, I'll end up with velocities that, depending on the circumstance, can vary as much as 100 fps within the same string. That isn't common, and one measure of a quality handload is much tighter grouping of velocities, but what it tells me is that I probably can't estimate velocities to within less than 100fps. And maybe not then.

Even a 1" difference in the length of the barrel can make a sizeable difference, depending on the powder.

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I have the Competition Electronics Prochrono Digital. Works great, I can hook up a remote control to it, it has been wonderful.

But here's an interesting alternative:

http://www.midwayusa.com/product/626107/caldwell-ballistic-precision-chronograph?cm_vc=ProductFinding

or the kit here:

http://www.midwayusa.com/product/628006/caldwell-ballistic-precision-chronograph-premium-kit?cm_vc=ProductFinding

The Chrono alone is currently on sale for $74.99. It has an error rate of .25 percent. The reviews are great. There's an app so it can be hooked up to your phone as a remote. My Prochono has a remote but it cost $50 at the time and now is a ridiculous $89.99.

If I had to replace my Prochono, I'd get this. You need a tripod as well but they even can be set on a table and supported that way.

************************************************** ***********************************


I have a Ruger GP100, 4" barrel in .38 special/.357 mag. I've been working up loads for it. My bullet mold drops about 125gr in linotype, so I was looking for a load in a manual that would get me there. I wanted to use Bullseye. As an example, in my One Book/One Caliber little spiral bound manual (the one that copies the load data from many bullet manufacturers/powder sources), the Lyman offering is for a 121gr bullet out of Linotype. Close enough, said me.

But note this and note well: the "firearm" used in Lyman's tests was a Universal Receiver and Special Vented Barrel. I don't have one of those. So I'm not sure how it will differ from what I do have. Sometimes manufacturers will use actual firearms; sometimes not. If you don't have the same exact firearm with the same exact dimensions....well, how different will you be? I don't know either. :)

Anyway, the book shows Lyman's max load of 4.6 grains of Bullseye for the bullet they list, which is not mine but is close. I used 4.0. The book shows a velocity of 1001fps for 4.6 grains; I produced an average of 834fps based on my own chronograph readings.

Those rounds had excellent accuracy. I did two separate strings of 5 shots, here's what I produced:



Hi
855
844


Lo
811
818


Av
838
829


ES
44
26


SD
17
10


#shots
5
5




(Hi=highest velocity, Lo=lowest velocity, Av=Average, ES=extreme spread, or hi minus lo, SD is standard deviation)

That's pretty good, btw. Same headstamp brass, same lot.

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Whenever I can get rifle rounds to where the standard deviation is 1 percent or less of velocity, I consider that extremely consistent. For handgun rounds, where the standard deviation is less than 2 percent, I consider that extremely consistent. The above shows excellent and acceptable consistency--according to my own standard.

But i have no idea how I'd be able to produce that information except from a chronograph. Part of the problem w/ cast boolits is the number of sources of data in manuals is limited--mostly to Lyman. There are the odd bullets made by other manufacturers (Hornady makes some, for instance), but if they're not the same as your bullet, you're left with estimating an estimate when it comes to guessing velocity.

BTW, I usually shoot some commercial ammo as a comparison baseline for my own workups. Here's some Winchester .38 spl 130gr FMJ data, same format as above.

First column is the Win ammo in my Ruger pistol; second column is the Win ammo in my Rossi 92 lever action; third column is my own handloads using the bullet that produced the above. Note the difference in consistency:





Win/Ruger
Win/Rossi
Me/Rossi


Hi
852
1036
1132


Lo
761
900
1088


Av
802
978
1107


Es
91
136
44


Sd
33
51
14


# shots
5
5
12



Compare my own handloads (the ones above and these) with the commercial ammo. Mine is much, much more consistent. This doesn't make me special--most people here can produce this kind of thing--it's why they handload, it's why they cast.

But part of that ability to produce consistency, for me, is having real data from which to evaluate the loads I produce.

Now, I'll admit--I'm a bit of a data junkie. More is usually better, from which I can draw better conclusions. But I cannot, just cannot imagine trying to do handloads--especially working up loads that may not exist in the manuals for bullets that don't exist in the manuals--without a Chronograph.

Just get one.

[mart]

There"s no substitute for shooting your load over a chronograph but I did run your load through Quickloads and came up with 1006 fps. Quickloads is pretty accurate on most rounds but it still pays to run it over a chronograph if you really need to know. If the load is doing what you want, you can just shoot it and not worry about the velocity.

[SteveS]

Thanks mart. Quickloads! I wasn't aware of that program. I looked over the website and it seems to calculate pressure also. Am I correct with that?

To complicate things a little more, it's not really velocity I'm concerned about, it's pressure. I just figured moderate velocity = moderate pressure but depending on the powder I guess that might not be a reliable assumption.

I'm looking for moderate pressure loads for my old Security Six. I want to do plenty of shooting with it without worrying about wearing it out.

[runfiverun]

pressure and velocity are not tied together except with the powder you are using.
you are producing gas from the powder, the more gas the more pressure, the faster you make that gas the more pressure.

you have the same volume of area to put that gas in.
except the part where the boolit is moving.
if you make it faster than the boolit is moving your pressure is going to be higher.

where a chrono is super handy is when you compare a new or unknown powder, you can get pretty close to the same on target results [on game the bullet will act the same regardless of how it got there] by duplicating the velocity, or by finding the grain for grain match.

[30calflash]

For velocity you can use the ballistics tables that are in the Lyman manual. Most have a 50 yard zero for handgun. You can measure your POI at 25, 75 and or 100 yards for bullet path above/below the line of sight with the same hold. Probably best to use point of aim, POI.

If the bullet being used is somewhat different try to choose a weight and style that is close.

Should give a good idea w/o the purchase of more equipment, if that's what you are looking for.

[mart]

Thanks mart. Quickloads! I wasn't aware of that program. I looked over the website and it seems to calculate pressure also. Am I correct with that?

To complicate things a little more, it's not really velocity I'm concerned about, it's pressure. I just figured moderate velocity = moderate pressure but depending on the powder I guess that might not be a reliable assumption.

I'm looking for moderate pressure loads for my old Security Six. I want to do plenty of shooting with it without worrying about wearing it out.

You didn't specify what cartridge your Ruger is chambered for, but I assumed a 357 Magnum although they made the Security Six in both 38 special and 357. Very good gun and very strong. I also had to guess at the bullet so went with a Lyman 155 grain SWC as it is a popular cast bullet. One has to remember Quickloads is an estimation based on the information we put into it. I also did not find much for Red Dot loads in my manuals. I did find one load for a lead 158 grain in an older Alliant manual the listed 6.5 grains at 36,000 psi. Quickloads estimates your load at 31,500 psi. Once again only an estimation. Your results may vary.

Quickloads is a valuable and useful tool for reloaders, especially when no or little data exists. I have three wildcats, a 6mmx222, a 375 Whelen and a 400 Whelen. Quickloads had been especially helpful with the 6x222 as almost no data exists for it and many powders are available today that were not when the little data there is was developed.

The 357 Magnum has a max pressure of 35,000 psi. It would appear your load is less than that.

[Blammer]

if it takes more than a second or so to hear the 100yd gong get hit, it's slow, if it's almost instantaneous, it's fast enough. :D

[MBTcustom]

Estimates of velocity, pressure, group size, or anything else are useless without having at least one rock solid piece of information based on an accurate measurement.
The speed is the most obvious choice in your case, and a chronograph only costs $80 brand spanking new.
There are just too many variables that could effect what you are looking to estimate, (such as barrel condition, twist rate, barrel length, powder burn rate within a particular lot, bullet hardness, lubricity of your lube, primer strength, cylinder gap, etc etc etc.).
The only way to call it anything more than I wild flying guess is to measure something about how your particular gun handles your particular load.

If you truly are after pressure, then using a chronograph to measure velocity, and transposing that to pressure is still a bit of a finger in the air kind of a guess, but at least you're basing it on something that has to do with your particular gun.

[SteveS]

Alright, you guys have convinced me. A chronograph will be my next purchase.

I now have six different powders to work with this summer and a chronograph really does seem to be the best starting point for me. Who knows, I might even get that Quickloads program before the summers over.

If I want to tailor my loads I guess some tools to get the job done is common sense.

Like I said, what goods a hobby if it don't drain the checking account. ;)

[Harter66]

I would like to over state the gun to gun variations. I have a 45 ACP that border lines on the impossible with mid range loads. It is over 100 fps faster than a sister/cousin pistol with the same loads. I also have had several "fast" rifles come and go, meaning that they were a lot faster with published data than the data said they should be from a shorter bbl no less. The Speer manual has an article called "why balistians get grey" .

[DrCaveman]

Excellent choice! Chronys are the same or less cost than a nice new mould, hard to justify not having one. Im sure youll pick a good one.

As harter says, it is mportant to recognize and appreciate the gun to gun differences. Ive had guns that showed major pressure signs below the stated velocity and within the charge weights. Others have shot way faster (or even other powders with the same gun) than manuals suggested they would. Interesting to see how inexact the science of reloading recipes really is

[olafhardt]

When you shoot your chronograph, there is a post here some where for that. I have claimed the closest accidental crony hit at 3 feet. It still works, sorta.

[Larry Gibson]

Having had Oehler chronographs (3 of them, still have them) since '75 and having chronographed thousands of load in many different cartridges and firearms I have learned one thing; attempting to estimate velocity by any of the afore mentioned means is a fools errand. Sometimes you can be fairly close but you can just as easily be way off. The only way to know the velocity of any load from any firearm is to measure it with a chronograph using a sufficient sample (test) size.

Otherwise if you want to guess give yourself a large +/- such as "800 - 1000 fps maybe". Even then it is all too easy to be wrong.

Larry Gibson

[SteveS]

Interesting to see how inexact the science of reloading recipes really is

I can certainly agree with that. I've seen some loads in the manuals that, compared to other loads in the same manual, just don't make sense to me.

It will be best to see what my loads are actually doing in my guns. It's too bad that accurate pressure wasn't easier to get but as goodsteel said, at least I'll have one accurate measurement to start with.

Larry, thanks for the recommendation of the Oehler chronographs. I'm going to have to do some studying on the subject before I make a decision on which to buy. Recommendations and experiences are always welcome.

[Shiloh]

Estimating velocity without a chronograph?? I have no idea how you would do that.

Shiloh

[mongoose33]

When you shoot your chronograph, there is a post here some where for that. I have claimed the closest accidental crony hit at 3 feet. It still works, sorta.

THE single best tip I've ever read was this: replace the metal struts that hold the sun shields with wooden dowels. If you or someone should happen to shoot one, all it will do is snap it. Shoot a metal strut and you quite possibly will take out the chronograph.

At least with my prochrono, there are standard dowels that fit it. Little sandpaper on the ends and they fit just fine.

[fredj338]

Without a chrono, you are only guessing. I don't care how long you have been reloading or what one gun tells you, they are all diff, especially revolvers. I have 5 diff 4" 357mags. They all give diff vel with identical loads. From slowest to fastest can be 100fps diff. So me telling you what one gun does & comparing it to your gun, almost pointless. It will be a guess, just like you are doing now.
Unless you need a specific vel, what your gun actually is doing isn't always important. Having said that, I have been using a chrono for 40yrs. I like knowing, not guessing. Most of the time it's just gather data, but if you gun game & need to know the PF or shoot past 100yds & need to figure drop & wind, invaluable. A chrono can also help you when reloading where no data is present. By comparing vel with known data, you can at least get an idea where you are going. Important in our current state of suing powders we may not be familiar with.

[mongoose33]

I'm afraid you're just going to have to break the bank and spend $50 on a chrono.



But he said he's good at it. I bet there's a checklist..

1) Does it come out of the barrel?
2) Does it go faster than the speed of light?


Last night, scholastic pistol program competition. Steel targets.

I had NEVER seen this before, but apparently the angle of the sun was just right--you could actually see the bullets in flight from gun to target, viewed from a sideways angle. Since I could actually see them, I'm guessing they were slower than the speed of light. :)

How fast were they going? I don't know, we weren't chronographing them. Knowing the components, probably in the area of 1100fps, plus or minus 200 fps. :)

[Litl Red 3991]

............
Is knowing actual velocity really worth the $100 or so that a chronograph costs? I'm going to have to give it a little thought.

You actually get more than just velocity from chronograph info. A lot more.

Look at the Average Velocity from your string and go from there.

You'll get velocity deviation, and that'll tell you how wide a range of velocities you're getting from that load. I just tested two different powders and one gave over 80fps deviation while the other showed about 20fps. Guess which one will give better accuracy (especially in elevation) at longer range. Just seeing the 80fps is a warning that powder isn't happy in that load. When you're trying for a lighter load, wide velocity deviation can be a warning the charge is too light. Think $100 is too much to pay for a chronograph? It isn't.

They also give you a couple of other numbers. There is a Standard Deviation and an Average Deviation. Don't worry about them, just notice the numbers. Consider them against the Average Velocity you got. You'll get used to what numbers you usually see, and what you were getting for on-target accuracy with those numbers.

For example, two loads were tested yesterday.
One gave average velocities of around 655fps. The max spread on those groups were over 60fps. The Standard Deviations were over 25fps.

The other gave AVs of around 671fps. Those max spreads were around 26fps. The SDs were around 12fps.

Two different powders. I won't be wasting any more of one of them. I also know to stop where I am with the other trying for a light load and maybe test with a touch more powder, as 670fps is more than low enough for what I want to do with that load. There is a lot more than just velocity you can get out of chronograph readings.

[Litl Red 3991]

I've used a Pact chronograph since the 90s when I paid about $100 for it. I noticed the other day they're selling for... about $100.

Yesterday I found out one pistol load was wasting powder and there was a good reason my 223 varmint rifle was pumping out groups just a touch under 1" at 200yds and 100fps faster than the loading manual said it would. Three things I wouldn't have known without that sorta ratty looking Pact feeding out the numbers.

[Wolfer]

I suspect there aren't many serious handloaders who don't have a chronograph. When I got my first one I found one of my rifles was 300 fps slow from the Sierra manual while another is very close.
With my 7x57 starting loads will get me near max velocity and mid loads will lock up the bolt.

Once I had a chrony I don't know how I made it without one.

I have the competition electronics pro chrono. I highly recommend it.

[DrCaveman]

Shot my chrony right where the diffuser connects to the rod a few weeks ago. That piece of plastic went a-flyin, i havent found it despite looking around on several occasions.

I was getting sick of muzzle blast causing chrono errors, so i went back to about 40 yds and shot a little too quick. Yeah bad shot, about 8" high and right of my POA.

The chrono registered "error 2" for that shot but my estimation is about 10 cps (chronographs destroyed per second, if they are all lined up 40 yds apart out to 400 yds).