Optimal barrel time mind warp cross eyed help?

[johnmventers398]

so. i do not have access to quickload. however i like the idea of trying to predict af far as is reasonable a zone to hone in on for my 270. i have read the OBT paper and think i understand the theory. however tring to do my own math i cannot make the nodes corrolate to reasonable muzel velocities. i want to try and work out a target muzel velocity by using V=D/T. so my barrel is 27" long and trying to do the math i seem to be getting low velocities at the smallest frequencies. so here is my calculation so you can help me find out what i am doing wrong and why i am getting the results that i am.. whith me? good because im confusing myself. . .

so D=27
T= 0.000915
V= 29,508.1967 i think this is inches per second?
devide by 15 to give feet = 1967.21311 feet.

and that is me lost.

i think i have my sum wrong but trolling the internet (as you do) i cannot find the equasion i am looking for so i kinda tryd to make it up.

what am i doing wrong? is this the propper equasion?

i am time and component poor so i would like to zone in before i set bank notes on fire.

help would be realy apreciated.

thanks

john

ps i am finding this so hard i can actuly feel it in my gut and its like i know whare i want to get to but as soon as i think im getting there ,the answer dissapeers into smoke. it is super frustrating but i do not want you to just tell me the answer. help on what i am getting wrong so i can work it out my self.

 

[Crow]

Fifteen inches to a foot?

 

[savagedasher]

so. i do not have access to quickload. however i like the idea of trying to predict af far as is reasonable a zone to hone in on for my 270. i have read the OBT paper and think i understand the theory. however tring to do my own math i cannot make the nodes corrolate to reasonable muzel velocities. i want to try and work out a target muzel velocity by using V=D/T. so my barrel is 27" long and trying to do the math i seem to be getting low velocities at the smallest frequencies. so here is my calculation so you can help me find out what i am doing wrong and why i am getting the results that i am.. whith me? good because im confusing myself. . .

so D=27
T= 0.000915
V= 29,508.1967 i think this is inches per second?
devide by 15 to give feet = 1967.21311 feet.

and that is me lost.

i think i have my sum wrong but trolling the internet (as you do) i cannot find the equasion i am looking for so i kinda tryd to make it up.

what am i doing wrong? is this the propper equasion?

i am time and component poor so i would like to zone in before i set bank notes on fire.

help would be realy apreciated.

thanks

john

ps i am finding this so hard i can actuly feel it in my gut and its like i know whare i want to get to but as soon as i think im getting there ,the answer dissapeers into smoke. it is super frustrating but i do not want you to just tell me the answer. help on what i am getting wrong so i can work it out my self.

Till you know all the above it is just a guess .
I stopped using it for that reason. It doesn't translate to other guns .
The only thing that matters is what you get on paper .
Then you add a tuner and most load work . Not being a smart ass spend more time at the range and not so much on the computer.
lol Larry

 

[johnmventers398]

Till you know all the above it is just a guess .
I stopped using it for that reason. It doesn't translate to other guns .
The only thing that matters is what you get on paper .
Then you add a tuner and most load work . Not being a smart ass spend more time at the range and not so much on the computer.
lol Larry

i would love to spend more time on the range but work and family comitments usualy mean it ends up dark before i get free time.

also at this point it is more than simply seeing results on paper it is about furthering my mathematic understanding and problemsolving.

 

[Twoboxer]

Using V=D/T you would be calculating something close to the average velocity during barrel travel, not the velocity at muzzle exit. So it's no surprise you'd get a low number even if you used 12 inches to the foot.

Since the acceleration and average velocity of bullets/powders that yield the same MV can differ, it's tough to do what you want without the aid of a calibrated QL.

My feeling is anything you could calculate absent using a calibrated QL is more likely to lead you astray than lead to success. Besides, the calculated nodes may not work for you, and there are other accuracy nodes than the ones predicted by the formula. Better to just run the OCW (at least close to) the way Newberry outlined. Results on paper will tell you what you need to know.

 

[brantfredrickson]

This is what a bullet acceleration curve looks like. Acceleration is not constant.

 

[ebb]

Savage Dasher lives a few miles from the best and only 1000 yd range in Florida. He thinks everyone can just run to the range and shoot anytime they want. Larry it just ain't like that for the rest of us. The range here in West Palm Beach is open 2 days per month, 4 days per month during and before hunting season.

 

[savagedasher]

Savage Dasher lives a few miles from the best and only 1000 yd range in Florida. He thinks everyone can just run to the range and shoot anytime they want. Larry it just ain't like that for the rest of us. The range here in West Palm Beach is open 2 days per month, 4 days per month during and before hunting season.

You use to don't tell your too old.
I have a private range I test at . And I don't use OBT. But I do use a tuner .
9 guns with the same powder drop 4 different barrel companies 28 to 31 barrels 3 are junk savages And all shoot . Larry

 

[ebb]

I said you shot at Manatee , you spilled the beans about a private range.

 

[dcali]

As was mentioned before, you need to integrate - nothing is constant. There are some decent books out there that get into the details of internal ballistics, but in the end you will need to know the powder characteristics, and ultimately the practical way to do that is to buy QuickLOAD. If you are simply looking at the math, try "Ballistics" by Carlucci and Jacobson. It's pricey, but it's a good college level overview of internal, external and terminal ballistics.

https://www.barnesandnoble.com/w/ba...sid=Google_&sourceId=PLGoP199&k_clickid=3x199

Also, in my opinion, OBT is flawed to the point where it doesn't work reliably, if at all. In reality what matters is seating depth and charge weight - in that order. And those variables are not completely independent. I can theorize about why that is (my guess is that charge weight helps to time with barrel vibrations, and seating depth helps to start the bullet into the bore straight), but we don't really know exactly what's going on. Because of that you have to test. All the math can do is get you to a starting point - once you're close, blind testing is the only way to hone in on the optimal load. that said, QuickLOAD is a very good way to get to a starting point. But so is asking other shooters, and so is a reloading manual.

It's my strong belief that using some proxy for group size is a fool's errand. That means ladder tests, OBT, or any scheme other than shooting groups. A clue that something is amiss is when you have to ask someone to help interpret your results.

 

[johnmventers398]

Fifteen inches to a foot?

well spotted!

 

[johnmventers398]

hmm ok it would seem that my brain is still fried. thank you for all of the input.

 

[SheepDog]

The math behind internal ballistics is best left to advanced calculus students and programs written by them. Even if you do the math and do it correctly you are only estimating the barrel time because you have no idea what the pressure curve is.
I've only been loading my own ammo for 48 years or so but I have tried just about every trick and gimmick that has come along. NONE of it beats shooting targets and adjusting powder charges. You have to plan your range time in advance and incorporate it into family time, When you go to the range have three to five rounds of five different powder charges separated by no more than 1% of the maximum charge.
Fire in round robin style on five different targets. From those groups and fired cases you can decide where to take the powder charge from there. If you find a load that shoots small groups then load more cartridges with =/- .3 grains on either side and shoot it again the next time out.

For this to work you have to have a gun that will shoot small groups and a shooter that can do the same thing with that gun.

When you find the smallest group with that powder, bullet, primer and brass then load up 60 rounds and at three different trips to the rang shoot 20 in four 5 shot groups each time. That will tell you if the load is consistently good or not.

If you don't find an accurate load then change one thing - powder or bullet or primer or case, but only one thing and start over.

When you get a consistently good group then you can adjust the seating depth to see if it gets better.

There is no shortcut to finding accurate loads.

 

[johnmventers398]

The math behind internal ballistics is best left to advanced calculus students and programs written by them. Even if you do the math and do it correctly you are only estimating the barrel time because you have no idea what the pressure curve is.
I've only been loading my own ammo for 48 years or so but I have tried just about every trick and gimmick that has come along. NONE of it beats shooting targets and adjusting powder charges. You have to plan your range time in advance and incorporate it into family time, When you go to the range have three to five rounds of five different powder charges separated by no more than 1% of the maximum charge.
Fire in round robin style on five different targets. From those groups and fired cases you can decide where to take the powder charge from there. If you find a load that shoots small groups then load more cartridges with =/- .3 grains on either side and shoot it again the next time out.

For this to work you have to have a gun that will shoot small groups and a shooter that can do the same thing with that gun.

When you find the smallest group with that powder, bullet, primer and brass then load up 60 rounds and at three different trips to the rang shoot 20 in four 5 shot groups each time. That will tell you if the load is consistently good or not.

If you don't find an accurate load then change one thing - powder or bullet or primer or case, but only one thing and start over.

When you get a consistently good group then you can adjust the seating depth to see if it gets better.

There is no shortcut to finding accurate loads.

so, i think that i have learned that i am asking to much of my self to work out the math.
i will do it the good old fashoined way.

 

[kvd]

johnmventers398,

You may have missed the point in post #2. There are only 12 inches in one foot. Your arithmetic is fine, your conversion factor is incorrect. If you divide your number above by 12 instead of 15 - you'll get 2459 ft/sec. Is that more like what you were expecting?

Ken

 

[savagedasher]

Optional barrel time is when the bullet leave barrel in the exact moment in time.
Then all the vibration need to have the barrel in the correct location to shoot small .
Any change in bullet speed Can change the results . That would be a moment in time
Have we ever got it perfect No
Some have got close but not perfect .
I don't know of any that have done it with math . Everyone has done it by shooting .
Lots of luck . lol Larry

 

[johnmventers398]

johnmventers398,

You may have missed the point in post #2. There are only 12 inches in one foot. Your arithmetic is fine, your conversion factor is incorrect. If you divide your number above by 12 instead of 15 - you'll get 2459 ft/sec. Is that more like what you were expecting?

Ken

i think i responded to the catch? but yeah that is more to what i would expect. although id be hoping more in the 3200 range.