Hello the campfire:
I have a question.
I do not have a chronograph. Velocity in and of itself has never made that much impression on me and my needs, as long as a published load was accurate. But I got to thinking last night and wanted to pose this question to the experts here. If I have a load of known velocity that pretty much follows the manual as far as point of inpact, is it possable to extrapulate increases or decreases in velocity from a change in that point of impact?
To illustrate:
I pick a load projected to give 2700 fps and zero on target at 200 yards. I am working up another load using the same powder and bullet, in the same rifle. I increase the powder by one grain each additional loading until I am at the book max load. I think that I will see the point of impact rise. Is this predictiable enough to questimate the velosity?
Judge Sharpe

quote:

Is this predictiable enough to questimate the velosity?

I seriously doubt it! Chronograph are as cheap as $65.......Get one and quit guessing.

Maybe if there was no vibration in the barrel. What happens is the barrel vibrates. Changing the velocity will change when in the cycle the bullet leave the barrel. Part of why you work up an accuracy load. Get the bullet consistantly leave at the end of the up or down cycle. I've had higher velocity loads impact both high and low to a 100 or 200 yd zero.

kinda what I figured. That is why, I assume. that various loads have smaller groups and differant rifles like differant laods. Correct me if I am wrong, but a heaver barrel shoots more loads well but a light may shoot specific loads better? What about harmonic dampners, ugly but effective of not?
Judt slow rainy day stuff you know.
Thanks
Judge sharpe

quote:

Correct me if I am wrong, but a heaver barrel shoots more loads well but a light may shoot specific loads better? What about harmonic dampners, ugly but effective of not?

It is possible to get a light barrel to shoot just as accurate as a heavy for a 3-5shot group. Just might take more work. The heavy barrel has less vibration and more forgiving. Bigger sweet spot. If you check the BR people they use a heavy barrel and they will all be about the same length. Around 20.5"(if the memory works). Because of harmonics.

Where the heavy barrel will really help is with heat. A light barrel will heat up quicker and can walk. A heavy barrel can do the same thing just takes longer.

The boss system and dampers will work. Yep they look ugly in my book. It that case you tune the barrel vibration to the load. Not the load to the vibration.

Pressure points at the front of the stock are to reduce total vibration. Trade off is a pressure point to bend around. I can't think of a case where I couldn't find a more accurate load with full freefloat vs pressure point.

Judge:

Are you asking whether the ballistic curve of a bullet, ie, how much does it drop at a given distance, can be used to estimate velocity by comparing it with published data for various loads? Yes. I'd "level" my barrel, put a target dot at 100 yds centered in the bore of my rifle, fire a round and see how far below the dot the bullet struck. (It would be better if you could do it at 200yds and 300yds too.) Some of the ballistic table will have bullet drop data. Compare your results with the bullet drop data for your bullet. The closest match will be your velocity. You may have to interpolate. Kudude

Barrel harmonics are awierd thing.
I have two loads for my 7x64
139gn Hornady internbond with 57.1 gn RL19
175gn Speer magtip with 53.9gn RL19
Guess what? They shoot to the same point of aim @ 110yds
This was a fluke observation not some cunning ballistic knowhow, however it is convenient.

Regards

Mark

Judge, I helped my future S-I-L make up some loads for his 257WBY and we hit the sweet spot at a pretty modest charge weight. We went ahead and fired some that carried more powder to see what they would do and the velocity became irratic and started declining rather than increasing and the accuracy went south as well. I guess what I am saying in a round-about way is that when it comes to ballistics there are more maybes than hard yes' or no's.

It is claimed by the Brits that the Lee-Enfield match rifles they use are somewhat compensating for variations in velocity. The lower velocity rounds in a string depart at a slightly higher angle than the higher velocity rounds. The supposed result of this is they shoot better scores at 900 yards than other teams due to less vertical shot dispersion. This is not an intentional design feature of the Lee-Enfields. Pretty strange.

quote:

The supposed result of this is they shoot better scores at 900 yards than other teams due to less vertical shot dispersion.

Doesn't make since to me but that wouldn't be the first nor last time. Would have to see bullet paths on that one.

Using bullet drop as an estimate of velocity makes logical sense, but in practice there are too many uncontrolled variables. I can recall reading articles from the 50’s when a lot of wildcats were being developed without chronograph data. The developers tried estimating velocities based on bullet drop, typically out to 300 yards. All their results were bogus.

As an example of how things just do not work out based on bullet drop, I recently compared data on my 308 after shooting in a couple of 600 yard matches.

I shot one load of 190 grain Hornaday, 44.0 grs Varget. Chronograph velocity is about 2575 fps.

The other load was with 168 Hornady was 40.5 grains surplus (and deteriorating!) 4895. My velocity was about 2625 fps.


At five hundred yards the 168 grain bullets required 1.5 MOA less elevation than the 190’s. According to predicted data, the 190’s should have required less elevation than the 168’s. Velocities were close, the averages are just averages, the highs and the lows on the velocities often overlapped. The Sierra loading manual tables on bullet drop and velocities do not agree with my real life experience. The book says that if a rifle firing 168's and 190's, both at 2600 fps is sighted in at 200 yards (with the respective loads), the 190's will be 86.65 inches low a 600 yards, while the 168's will be 94.73 inches low at 600 yards. Sounds like the 190's should be ballistically better and flatter shooting. And I believe the 190 is ballistically better, and probably is flatter shooting, but the readings on my rear sight do not lie. It took more elevation to put the 190’s in the center of the target.

My conclusion, you cannot rely on bullet drop or elevation settings as a measure of velocity.

Go buy a chronograph and find out what you are doing in your load development.

quote:

Originally posted by SlamFire:
Go buy a chronograph and find out what you are doing in your load development.

But with all of the above info, the chrono won't be any use at all. EG it may show a higher velosity, but where is the bullet going to go?
Any time I've borrowed a chrono the velosity was as advertised, or more often much lower, and I wouldn't care to try to gain some pie in the sky fps figure that was due to my short barrels.

Heck, you buy all these reloading manuals you are paying for them to have done most of the development work. Chrono's are for gunwriters to keep the bastards honest.

I would think if you had a bullet of known bc ,you could easily get a ROUGH estimate of its velocity by its trajectory curve.
Remember ballistics is a science,ask anyone who was in the artillery in the army,A projectile of known bc fired at a certain velocity with the barrel on a certain angle will strike in a predictible place,time after time.

Yeah, well try to tell that to my old man.
Marching along in Syria when one of our own 25pounders dropped short and took his arm off.
Just the one mind. Shot I mean. Most went over OK.

Ignoring harmonics (for a moment), the slower bullet will hit higher, due to muzzle rise during recoil (increased barrel time).
Ignoring the barrel time issue, but assuming both are zeroed at the same distance, the faster bullet will be lower out to the Max Ord, and higher beyond that.

quote:

Originally posted by JudgeSharpe:
[1] I do not have a chronograph.

[2]is it possable to extrapulate increases or decreases in velocity from a change in that point of impact?

To illustrate:
I pick a load projected to give 2700 fps and zero on target at 200 yards. I am working up another load using the same powder and bullet, in the same rifle. I increase the powder by one grain each additional loading until I am at the book max load.

[3] I think that I will see the point of impact rise.

[4] Is this predictiable enough to questimate the velosity?
Judge Sharpe

1: get a chrony... www.shootingchrony.com has then for FORTY FIVE bucks.. the price of some primers and 2 cans of pounder.

2: only "directionally", that is, up or down

3: NO! a faster load, in that circumstance, will print LOWER... i repeat, zeroed for 200 yards (without changing the scope) and taking the same bullet and making it go faster will result in it printing LOWER... remember that bullets do NOT travel in a straight line, they are launched (usually) slightly upwards. dwell time in the barrel UNDER RECOIL changes with a faster load... since everyone knows a rifle pitches UP when you pull the trigger, the bullet is not in the barrel as long, and the arc is not as pointed as "UP" as the previous slower load. try it.


4:nope

Hey Judge, Thanks for the question to the Board. It is a good one which is getting a lot of varied responses. You can tell a lot about a persons Hunting style by looking at the above answers.

quote:

Originally posted by JudgeSharpe:
Hello the campfire:
I have a question.
I do not have a chronograph. Velocity in and of itself has never made that much impression on me and my needs, as long as a published load was accurate. But I got to thinking last night and wanted to pose this question to the experts here. If I have a load of known velocity that pretty much follows the manual as far as point of inpact, is it possable to extrapulate increases or decreases in velocity from a change in that point of impact?

Huuummm, If you have a Surveyor take his equipment and survey an absolutely "Straight Line" from the shooting bench all the way down the Range and then determine the exact "Height" to hang a Target at each Surveyed distance you want the Bullet to make an Impact, you can do this. You will need to fire a "Single Bullet" through Two(or more) Targets placed in direct alignment with each other. Then measure the Drop and plug the results into any Ballistics Program to determine a "software guesstimate". It is still a Guess because of variations in the Ballistic Coefficient, exact Bullet weight, etc.

quote:

I pick a load projected to give 2700 fps and zero on target at 200 yards. I am working up another load using the same powder and bullet, in the same rifle. I increase the powder by one grain each additional loading until I am at the book max load. I think that I will see the point of impact rise.

Any of the above responders who said it depends on the "Harmonics" are correct. It might go up slightly, stay about the same or go down slightly.

quote:

Is this predictiable enough to guestimate the velocity?

Here is where a lot of folks and I disagree. Doesn't harm a thing for them being WRONG!

Sure you can guess the Velocity and it is just as "useful" as shooting a chronograph. And you never have to fire a cartridge to do it. You just guess based on what the Manuals average out, adjust for the difference in barrel length and subtract 150fps.
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So Judge, What do you want to do with the Velocity once you "think" you know what it is - guessed or chronographed? Either way you get it, it really doesn't matter, because the ONLY THING it tells someone is how fast a particular Bullet went - nothing else.

You can use the (guesstimated or measured) Velocity to "guess at" the Trajectory by use of a Ballistics Table. Either way, you get the same results - more guestimates.

And you can use it to "guess at" the Retained Energy at a specific distance. This should be done before ever buying the firearm to see if it provides the performance needed for the intended Game and your specific style of Hunting.
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I'll offer that you are best served to totally avoid wasting your time shooting chronographs and focus on Developing an accurate, SAFE MAX Load while watching for all the Pressure Indicators. Then "guess" the velocity and use the Ballistic Tables to get a "guessed at" Trajectory. And finally, go shoot the rifle with the actual Load and create your own Drop Chart at any distances you think you will be shooting.

Without doing the actual shooting to create the Drop Chart, it is all just "guessing" anyway.

quote:

I'll offer that you are best served to totally avoid wasting your time shooting chronographs and focus on Developing an accurate, SAFE MAX Load while watching for all the Pressure Indicators. Then "guess" the velocity and use the Ballistic Tables to get a "guessed at" Trajectory. And finally, go shoot the rifle with the actual Load and create your own Drop Chart at any distances you think you will be shooting.

I agree almost 100%. Problem I have is more of my rifles are my own wildcats. Thus no loading manuals. So velocity, velocity changes between charges, head expansion, visual inspection all help me set my upper limit all the time looking for a load with acceptable accuracy. Then I run it through a drop calculator to set an initial guess as to Max Pointblank. Then go and test my results out to 300-600yds depending on the cartridge. Then adjust zero as needed.

[QUOTE]Originally posted by Hot Core:

I'll offer that you are best served to totally avoid wasting your time shooting chronographs and focus on Developing an accurate, SAFE MAX Load while watching for all the Pressure Indicators. Then "guess" the velocity and use the Ballistic Tables to get a "guessed at" Trajectory. And finally, go shoot the rifle with the actual Load and create your own Drop Chart at any distances you think you will be shooting. QUOT]

Golllleee Wow! First you relagate my scout rifles as tire irons and now you want me to shit can my Oehler. roger

Hello the campfire:
Thanks, I think for all of the resposes to my mindless museings. To tell the truth, all I am interested in is a good safe load, and reasonable accurate. I enjoy gadgets as much as the next guy, but when I can safely put a 139 grain .280 in the proper place on a white tail at 100-150 yards I am satisfied (min. of Whitetail??) The speed at which I reach out and touch hin (or her these days) dosn't matter as long as it is fast enough for the the bullet to mushroom as it was designed.
The factor that kills my idea is not so much the ballistics of the rifle or amunition, but the ability of my 56 year old used and abused body to hold on a target steady enough to have reproducable shots. Even off a rest, I am not as good as I like to think I once was. Nowdays I know when I need to practice when the crickets in my ears get quiet, and my right arm is not blue any more. My open heart surgery has caused my pulse to be much better, guess what that does to a group!
This is a fun activity for me, not a profession. I am still practicing law. You would think I would have it doen after 25 years.
Judge Sharpe

quote:

Originally posted by Hot Core:
I'll offer that you are best served to totally avoid wasting your time shooting chronographs and focus on Developing an accurate, SAFE MAX Load while watching for all the Pressure Indicators.

Sorry,

The best way to develope safe loads IS to shoot over a chrono, watch for rpessure signs, and look for either a spike or flat spot in velocity.. and STOP WHEN IT HAPPENS

I was wrong when i said 45, it's 49 bucks, or 2.2 cans of powder...

an excellent investment

jeffe

quote:

Originally posted by bartsche:
...Golllleee Wow! First you relagate my scout rifles as tire irons and now you want me to ... can my Oehler.

I saw where you were poor-mouthing the 308Win as a Scout and telling the guy where the 30-06 would be a HUGE improvement. Did you think he would have trouble "hearing" the 308Win Report?

And since Roger is one of the very best folks to frequent these Boards, I'll make this one(and only one) exception and say he should continue shooting his Oehler(By the way, I saw that thread too. ) If you had been using a 308Win, one shot would be all it takes to put it in the can.
---

Hey Judge, If you are only Blasting Bambis at 100-150yds, then the velocity is not nearly as important. Even the Minimum Manual Loads would do well for you.

If you happen to be wise enough to own one of the truly outstanding cartridges of the entire world - the 308Win - you can use Minimum Loads for the 150gr or 165gr bullets and Kill every Deer you shoot at. Of course you don't want it hampered by having the Scope mounted in a goofy position.... like way out yonder on the Barrel.

quote:

Originally posted by Hot Core:
[QUOTE]Originally posted by bartsche:

If you happen to be wise enough to own one of the truly outstanding cartridges of the entire world - the 308Win - you can use Minimum Loads for the 150gr or 165gr bullets and Kill every Deer you shoot at. Of course you don't want it hampered by having the Scope mounted in a goofy position.... like way out yonder on the Barrel.

I stand Humbled roger

quote:

pick a load projected to give 2700 fps and zero on target at 200 yards. I am working up another load using the same powder and bullet, in the same rifle. I increase the powder by one grain each additional loading until I am at the book max load. I think that I will see the point of impact rise. Is this predictiable enough to questimate the velosity?

Although your approach is similar to what a lot of people used to do to "determine MV", it really is not reliable. For example, it is just as possible that your bullet will strike lower on the target rather than higher. For one thing, the point where the barrel is in its vibration pattern when the bullet emerges may be lower than when a slower bullet clears the muzzle. Then there's the "barrel time" effect. (Just two factors of several influencing point of impact)....

quote:

Heck, you buy all these reloading manuals you are paying for them to have done most of the development work. Chrono's are for gunwriters to keep the bastards honest.

Chronos are for people who REALLY WANT TO KNOW how a given load performs in THEIR INDIVIDUAL rifle, ("ALL RIFLES ARE INDIVIDUALS") and are not satisfied with what a gunwriter hack, some factory, or some reloading manual claims - I am one of these people......

El Deguello, while your there?
You've made me feel a bit um... inadequate.

So you determine exactly your velosity. Now what do you do with that figure?

Now take me for example, with a .223 rem 27" barrel full load then down a whisker, Powder and load tested by a few different companies.

Sighted in from 100 to 900 yards, very simular to the performance of a 150gr .308 each range.

Gets to 900 y still over the sound barrier.

I havent the slightest idea of the velosity, and what would I do if I did know??