If you use the same bullet, brass and primers , but use different powders and you have the same velocity through a chrony, how does it effect trajectory? Seatle an argument with my reloading buddy. Thanks

Assuming all shots leave the bbl at the same velocity, trajectories will/should be the same. However, a different powder, while producing exactly the same velocity may shoot to a different point of impact. Barrel harmonics, recoil and such all playing some role in the point of aim/point of impact equation.

The trajectory will be different, mainly because of the burning characteristics of the powder. Some burn faster, some burn slower. Because the bullet leaves the barrel at the same velocity, it does not mean that the bullet reached that velocity at the same time.

Then the barrel harmonics come into play. Some powders will reach 60,000 PSI in 1-1/2" of barrel travel, others will reach that 60,000 PSI in 2-1/2". This makes a difference.

Well tell me this. How much difference will there be??
I have loads using the same bullet but different powders and nearly identical velocities and they only vary 1 inch from each other at 600 yards the faster load being the highest POI.

The trajectory will be the same. A bullet does not accelerate once it leaves the barrel. It accelerates from position zero (chamber) out to the end of the barrel. Once it leaves the barrel, there are no forces acting upon the bullet that would sustain acceleration. Muzzle blast, maybe, to a small extent, but not enough to have any significant effect. BTW, a bullet leaving a 24" barrel at 2600ft/s experiences an acceleration equal to 52,484 "G's". WOW!!!!!!!!

quote:

The trajectory will be different, mainly because of the burning characteristics of the powder. Some burn faster, some burn slower. Because the bullet leaves the barrel at the same velocity, it does not mean that the bullet reached that velocity at the same time.

I'll have to call Bull on that. Physics formulas that Ballistic Calculators are programed w/ all work w/ the velocity, BC, and weight of the projectile.

The trajectory of the two identical projectiles will be the same.

Steve, if you know of some different equations for achieving this data, Please Share.

Reloader

dennis duke ----- If it happens once, okay what do you know. You know that it happened once. I would have to see it repeated several times to say that it is in fact true. ----- I would have to agree with Steve, each powder imparts it own conditions to that barrel and bullet, and no two burn rates are exactly the same. ----- Now how much difference it would make may be very small when figured into the overall equation, but in my opinion there would be a difference. Good shooting.

quote:

Originally posted by ricciardelli:
...Because the bullet leaves the barrel at the same velocity, it does not mean that the bullet reached that velocity at the same time. ...

Hard to believe some of you are not agreeing with Steve, simply because he is correct.

If you want to understand the principal of this so you can see what he is describing as it happens, simply visit any 1/8th or 1/4 mile Drag Race Track near you. The vehicle with the fastest speed does not always get to the end of the trap in the shortest time span. Disregard the "handicapping" time and just look at the pure Times and Speeds.

In the rifle situation, yes the harmonics are always different. They could be on a "similar" Harmonic, but not the "same" harmonic.

quote:

Originally posted by muffin:
Assuming all shots leave the bbl at the same velocity, trajectories will/should be the same. However, a different powder, while producing exactly the same velocity may shoot to a different point of impact. Barrel harmonics, recoil and such all playing some role in the point of aim/point of impact equation.

I'll take this side.....

Dennis, if I follow your question correctly I would say yes, changing powder can do this. Time of flight defines trajectory, or drop actually, and I think it has been clearly established that different powders can influence BC, all else being equal. The mechanics of this are something I don't know a lot about, but as an example it is known(engineered actually) that ball powders generally burn cooler than stick powders, and thus a bit dirtier. The bullet picks up this residue upon firing, and though minuscule in effect, it does alter BC due to parasitic drag and I think possible differences in drag, or resistance to passing down the barrel. Another point mentioned above, more of less, is that velocities may be equaled with different charges of different powders, and different pressures. With the exception of monolithic solids, all bullets obturate to some degree, even jacketed bullets propelled by smokeless powder. The extent of obturation also influences shape, and that influences BC, even if in small ways.

With all that said, it is unlikely you will be able to notice the difference while using a big game rifle inside of 300-400 yards.

HotCore - There are two very distinct areas when firing a bullet, acceleration and deceleration. The first (acceleration) being when the bullet is in the barrel. The second (deceleration), when the bullet is out of the barrel. Let's take a look at the first area. Take for instance two different rifles firing a 180gr bullet at 2700fps. The first rifle only has a 22" barrel, but the second rifle has a 26" barrel. The first bullet is accelerating at 1,991,803 ft/s^2. The second bullet is accelerating at 1,687,500 ft/s^2. BUT they BOTH leave the barrel at 2700fps. And the instant they leave the barrel, they have gone into the second part of firing a bullet - deceleration. Given the exact same bullet profile, these two bullets will decelerate at the same rate. If anyone can demonstrate how a bullet continues to accelerate once there are no more acceleration forces acting upon it, they me be up for the next Nobel Peace Prize in Modern Physics... (not to mention jobs at modern ammunition companies)

quote:

Originally posted by Hot Core:
[QUOTE]Originally posted by ricciardelli:
...QUOTE]Hard to believe some of you are not agreeing with Steve, simply because he is correct.

That Hurricane must have caused you more stress than I thought.

If the points of impact at ,let's say 100 yds., are close than the drop per increment of distance for each will be the same.

If you are saying,however, that the actual paths of the bullets will differ because because of different point of impact from the point of aim; that is correct.

If we have two different groups of cartridges with exactly the same bullets but different powder. Each leaves the end of the barrel with the same velociy. The cartridges from one group hit the target 2" lower at 100 yards.We meticulously adjust the scope so that group hits the target at the same place as the other group. Do they fallow the same trajectory? Why ,yes ,roger, of course they do.

You never get a crescent eyebrow from a scout rifle.

quote:

Originally posted by ManCannon:
...BUT they BOTH leave the barrel at 2700fps. And the instant they leave the barrel, they have gone into the second part of firing a bullet - deceleration. Given the exact same bullet profile, these two bullets will decelerate at the same rate. If anyone can demonstrate how a bullet continues to accelerate once there are no more acceleration forces acting upon it, they me be up for the next Nobel Peace Prize in Modern Physics...

Hey MC, No one is disagreeing with with any of that. If you believe we are in disagreement, then you have misread my post.

Best of luck to you.

quote:

Originally posted by Hot Core:

quote:

Originally posted by ManCannon:
...BUT they BOTH leave the barrel at 2700fps. And the instant they leave the barrel, they have gone into the second part of firing a bullet - deceleration. Given the exact same bullet profile, these two bullets will decelerate at the same rate. If anyone can demonstrate how a bullet continues to accelerate once there are no more acceleration forces acting upon it, they me be up for the next Nobel Peace Prize in Modern Physics...

Hey MC, No one is disagreeing with with any of that. If you believe we are in disagreement, then you have misread my post.

Best of luck to you.

Sometimes we see things differently from a different perspective

quote:

Originally posted by bartsche:
That Hurricane must have caused you more stress than I thought.

Yes indeed, lots of stress when they are "planning" to put people back in that mess before it is cleaned up, without adequate water, etc. and now "Rita" is planning a surprise visit for everyone over there in that mess. Maybe they can just spread the $200 Billion out on the ground with dozers and soak it all up.

quote:

If the points of impact at ,let's say 100 yds., are close than the drop per increment of distance for each will be the same.

If you are saying,however, that the actual paths of the bullets will differ because because of different point of impact from the point of aim; that is correct.

If we have two different groups of cartridges with exactly the same bullets but different powder. Each leaves the end of the barrel with the same velociy. The cartridges from one group hit the target 2" lower at 100 yards.We meticulously adjust the scope so that group hits the target at the same place as the other group. Do they fallow the same trajectory? Why ,yes ,roger, of course they do.

You know those clicking Beer Mugs , there they are. I find it interesting that as pitiful as I wham this stuff in, I do believe you had been "clicking the mugs" a bit before you posted.

I'd try to respond, but need you to clarify what you were/are toasting-to or talking about. What language are you speaking? (Just put 12-PBRs in the cooler. Had them for 2-weeks and it just dawned on me they were in the garage.)

quote:

You never get a crescent eyebrow from a scout rifle.

Profound indeed!

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HotCore - There are two very distinct areas when firing a bullet, acceleration and deceleration. The first (acceleration) being when the bullet is in the barrel. The second (deceleration), when the bullet is out of the barrel. Let's take a look at the first area. Take for instance two different rifles firing a 180gr bullet at 2700fps. The first rifle only has a 22" barrel, but the second rifle has a 26" barrel. The first bullet is accelerating at 1,991,803 ft/s^2. The second bullet is accelerating at 1,687,500 ft/s^2. BUT they BOTH leave the barrel at 2700fps. And the instant they leave the barrel, they have gone into the second part of firing a bullet - deceleration. Given the exact same bullet profile, these two bullets will decelerate at the same rate. If anyone can demonstrate how a bullet continues to accelerate once there are no more acceleration forces acting upon it, they me be up for the next Nobel Peace Prize in Modern Physics... (not to mention jobs at modern ammunition companies)

Correct, They have the same trajectory. Acceleration has no effect once the projectile has exited the BBL.

Now, when you fellas take into consideration that these bullets are probably being chronoed at 12-15 feet it only applifies the conclusion that they will follow the same path.

I just can't figure out why anyone would think that a bullet accelerates after it leaves the bbl .

Reloader

quote:

Originally posted by Reloader:
...I just can't figure out why anyone would think that a bullet accelerates after it leaves the bbl ...

Back many years ago there was a company (maybe Daisy) that created a firearm called a Gyro-Jet (I think) which had a solid propellant base attached to a Bullet. I believe I remember it only being available in a "Pistol Size" handgun with a barrel that was vented most of it's length. Been too long ago for me to remember all this stuff. Someone interested in wierd firearms (Roger? ) might remember it better than me.

It did accelerate inside and outside the barrel, or Alignment Tube. Not very accurate as I recall. Accuracy even worse than a Scout Rifle.
---

But, that really has nothing to do with this thread and current cartridges.

2 identical bullets traveling at the same velocity will drop at the same rate, as acted upon by gravity. (basic physics).
The point of impact with different powders can change due to bbl harmonics.
Mike

quote:

Back many years ago there was a company (maybe Daisy) that created a firearm called a Gyro-Jet (I think) which had a solid propellant base attached to a Bullet. I believe I remember it only being available in a "Pistol Size" handgun with a barrel that was vented most of it's length. Been too long ago for me to remember all this stuff. Someone interested in wierd firearms (Roger? ) might remember it better than me.

That reminds me of when we were kids we used to get a bushle of bottle rockets and find some pipes of some sort and some of dads tape to tape up one end. One fort on one side of the street and one on the other. Good Times.

I guess now I can see why they are illegal around here now .

Reloader

quote:

Originally posted by Hot Core:
Someone interested in wierd firearms (Roger? ) might remember it better than me.

I remember. Kind of a spin off of the recoiless rifle Korean police action era. roger

Thanks guys. I guess I opened a can of worms. One other thing is these loads are used in the same rifle.

If you look at the various programs for reloading you will see something called "barrel time" and this is probably more important to accuracy than it is to trajectory. Barrel time can be affected by almost everything -- the bullet used (how it interacts with the barrel), the primer (how quickly it ignites the powder) and the powder itself. The accuracy is related to barrel harmonics.

A couple of questions; How can he know that the point of impact is off 1" at 600 yds?, If the BC
varies with powder types, how do identical bullets
with the same velocity know which powdwr was used.
A change of powder may effect a chronograph reading due to muzzle blast, but the bullet once it
leves the muzzle is on it's own.
Good luck!

Reloader,

As teenagers, we used to do the same thing only from jon boats in a lake in Florida. Sometimes we used roman candles. We also made a cannon that mounted in the oar lock and was made from a grease gun body with the guts removed. We put a fuse of a cherry bomb out the hole where the pump handle used to be and shot cone shaped wooden furniture legs at each other. They would go several hundred yards and hit with a lot of power. The furnature legs worked great and they floated too. Only one trip to the hospital as I recall...I think it was a broke finger or something minor.

Good thing we survived that so we could go to SEA a few years later and do it for real.

quote:

Reloader,

As teenagers, we used to do the same thing only from jon boats in a lake in Florida. Sometimes we used roman candles. We also made a cannon that mounted in the oar lock and was made from a grease gun body with the guts removed. We put a fuse of a cherry bomb out the hole where the pump handle used to be and shot cone shaped wooden furniture legs at each other. They would go several hundred yards and hit with a lot of power. The furnature legs worked great and they floated too. Only one trip to the hospital as I recall...I think it was a broke finger or something minor.

Good thing we survived that so we could go to SEA a few years later and do it for real.

You know when you look back on your childhood memories sometimes it just amazes you how you got by w/ all those crazy stunts.

Have a Good One.

Relaoder

what MikeN posted as near as i can tell skimming thru is the one that addressed the crux of the matter. bullet drop is a function of GRAVITY acting on the bullet. is makes absolutely no difference whatsoever if it takes one bullet .003 seconds and another 2.5 hours to exit the muzzle. if the both exit the muzzle at exactly the same velocity gravity acts upon them in exactly the same way. the ONLY way barrel time comes into play is the aforementioned changes in harmonics causing a different point of impact.

but if both barrels were levelled out perfectly and each fired an identical bullet to an identical velocity they'd drop the same RELATIVE TO THE RIFLE's BORE over a given amount of time.

however, you change the powder barring unlikely coincidence, you'll change the POI which would give the impression it was dropping more, or less, depending on bbl vibrations which could allow a misinterpretation of the phenomenon you're seeing.

You can have two bullets leave the barrels with the same velocity with two different powders and have a big difference in place of impact. I have seen this demostrated when the crony showed 3000 FPS on two different rounds using same bullets, cases, primers and seating. The barrel harmonics were different for the two and caused one to hit 1.5 inches lower that the other. It is the same thing when two different rifles shooting the same rounds with the same velocity will impact differently. I have seen a 3 inch difference because of different powders. The path of the bullets may be simular because of weight and velocity, considering each rifle is zeroed in at the same distance. Also I have seen a good bit of diferance between short and long bbls using the same velocity load.

Thanks everyone, now I'm smarter than I was, AGAIN>

quote:

Originally posted by willmckee:

but if both barrels were levelled out perfectly and each fired an identical bullet to an identical velocity they'd drop the same RELATIVE TO THE RIFLE's BORE over a given amount of time.

Only in a vacumn, right? Shooting into a strong headwind wind will print higher than shooting with an identical tailwind.

quote:

Originally posted by tiggertate:
Shooting into a strong headwind wind will print higher than shooting with an identical tailwind.

Now are you sure of that? I was under the impression bullet drop was a factor of time of flight, and over longer distances a headwind will slow a bullet and a tail wind increase its speed. Generally speaking.
John L.

There is no answer to your question as both are correct, it can go either way...

Some rifles shoot damn near any load to the same POI, and these are the ones to keepa as they are far and few between...

Some rifles will change with any minor change in any component....

With any of these changes trajectory and accuracy can be effected to one degree or another..

quote:

Originally posted by dennis duke:
If you use the same bullet, brass and primers , but use different powders and you have the same velocity through a chrony, how does it effect trajectory? Seatle an argument with my reloading buddy. Thanks

IF specific bullets leaves the miuzzle at a given velocity, they will all have the same identical trajectory regardless of what propellant is used to launch them, AS LONG AS THE BULLETS ALL DEPART THE MUZZLE AT THE SAME POINT IN IN THE BARREL'S ARC OF VIBRATION! How many nanoseconds it takes a bullet to reach its muzzle velocity is only significant as barrel time relates to the point of departure in that vibration arc. Nothing else makes any difference at all.

quote:

Originally posted by Hot Core:

quote:

Originally posted by ricciardelli:
...Because the bullet leaves the barrel at the same velocity, it does not mean that the bullet reached that velocity at the same time. ...

Hard to believe some of you are not agreeing with Steve, simply because he is correct.

If you want to understand the principal of this so you can see what he is describing as it happens, simply visit any 1/8th or 1/4 mile Drag Race Track near you. The vehicle with the fastest speed does not always get to the end of the trap in the shortest time span. Disregard the "handicapping" time and just look at the pure Times and Speeds.

In the rifle situation, yes the harmonics are always different. They could be on a "similar" Harmonic, but not the "same" harmonic.

Agreed. But if all the bullets departed at the same point in the arc of barrel vibration, their paths will be essentailly identical, regrdless of what kind of powder was used to produce the identical MV.