Was reading a funny thread over at another gun related forum and bullets increasing in velocity after leaving the barrel was talked about. I thought it was pretty funny, but then tracers popped into my mind. As an amatur pyrotechnic chemist that I am, I have seen quite a few different tracer compositions and some burn quite violently. My question is could that violent burning action cause enough thrust to actually increase bullet velocity downrange?
Tracers increase velocity?
- Thread starter Maser
- Start date
Hmmm! Kinda an out of the bbl rocket effect from the tracer material?? My vote in no. I cannot believe it would make up for the immediately beginning velocity loss as soon as (or before) the bullet leaves the bbl. Ever thought about heavy loads causing an increase. Like a full up 308 load from my 18.5" carbine giving a boost upon bbl exit. Nah, me either. Chrony at 10' also says the answer is 'no', and , in fact, the short bbl is [just slightly] slower than my 24". Maybe someday I'll check it at 30'
I don't know if anyone has measured the specific impulse of a tracer, but if the bullet does have a SI, then yes, it might increase the velocity of the bullet during its trajectory.
One bit of evidence that says it doesn't affect the velocity is the fact that tracers are used specifically to see where the bullets, tracer and non-tracer types, are hitting. If the tracers had different velocities and therefore different trajectories, the usefulness of the tracers would be lost. Of course, if the difference in velocity is small, the change in trajectory over a nominal distance would also be small (a few inches) and wouldn't matter much.
One bit of evidence that says it doesn't affect the velocity is the fact that tracers are used specifically to see where the bullets, tracer and non-tracer types, are hitting. If the tracers had different velocities and therefore different trajectories, the usefulness of the tracers would be lost. Of course, if the difference in velocity is small, the change in trajectory over a nominal distance would also be small (a few inches) and wouldn't matter much.
I would imagine that the initial velocity would be slightly higher because the tracer round should be a little lighter than the regular - the chemical compound would be less dense than the normal lead core. Of course the constantly changing weight of the bullet as the compound is consumed and whatever thrust is imparted from the burn should really mess up any precision that may have existed in the first place.
I would put the possible thrust from the burning compound at the bottom of a list of several reasons that tracers are less accurate than their non-tracer counterparts.
As deadin noted, a tracer bullet has a constantly changing weight as it travels; a tracer may not have the same jacket composition as a regular bullet; a tracer may not have the same ballistic coefficient as a regular bullet (and as the compound burns the BC changes ever so slightly); a tracer may not have the same stability in flight as a regular bullet (due the preceding factors), etc., etc.
Fwiw......
Long ago in another life, I was among a group of grunt Marines tasked
with guarding a garbage dump. As bored young men will do, we found
ways to amuse ourselves. One way was prying the bullet out of an M-16
cartridge, dumping the powder, replacing the bullet, then inserting the
round into a fuse lighter, and voila, we had low velocity zip guns. We plinked
at rats, cans, and other garbage.
Somebody made the mistake of using a tracer round. There was a "LITTLE"
difference. When he pulled the firing ring, the round fired like a regular
"loaded" cartridge. And the end of the plastic fuse lighter was black and
splintered.
We discontinued "zip"gun practice for the day.
Walter
Long ago in another life, I was among a group of grunt Marines tasked
with guarding a garbage dump. As bored young men will do, we found
ways to amuse ourselves. One way was prying the bullet out of an M-16
cartridge, dumping the powder, replacing the bullet, then inserting the
round into a fuse lighter, and voila, we had low velocity zip guns. We plinked
at rats, cans, and other garbage.
Somebody made the mistake of using a tracer round. There was a "LITTLE"
difference. When he pulled the firing ring, the round fired like a regular
"loaded" cartridge. And the end of the plastic fuse lighter was black and
splintered.
We discontinued "zip"gun practice for the day.
Walter
Rangefinder
New member
My notions on tracers' lessened accuracy lean toward the fact that there is a small amount of burning substance traveling with the bullet. A single blade of grass is enough to adversely effect a bullet's flight stability--it doesn't take much. With a tracer, the heat may cause minor expansion and deformation within the metal of the jacket, and gases expended may effect the air flow around the base. Even in such minute amounts, they still may be enough to cause changes within the bullet's performance in flight.
As to causing an INCREASE in velocity? I seriously doubt it.
Just my random thoughts, shot from the hip.
It would seem to me that the burning tracer compound, without burning in a nozzle of some sort, wouldn't enact any more velocity toward the bullet than away from it in any of the 359 other degrees of possible direction, therefore would not increase velocity. Now, burn that compound inside a container with a nozzle and I would bet you get at least a little velocity. You just need to contain in order to harness that energy. An old criminalist instructor of mine always used to say compression= explosion. Without compression, it is just a burn.
Capt. Charlie
Moderator Emeritus
We occasionally used RAP (Rocket Assisted Projectiles) rounds in our 5" naval guns, and they significantly increased both range and velocity (sustained). A tracer could be similar, but it would depend mainly on how the burning gasses are vectored. If they're simply sprayed out aft with no focus, I doubt you'd see much difference. But if all of the gasses were concentrated in a single, aft direction through a small nozzle or port, I don't think there's any doubt that you would see a difference. How much of a difference though, I have no idea.
Perhaps, but not a signifcant amount
The "cup" in the base of the bullet holding the tracer compound would act like a very broad nozzle, but only to a very small extent. I doubt it there would be a measurable difference in velocity outside of the normal shot to shot variation.
Often tracer bullets are not lighter than ball, they are longer for the same weight. That way they obtain velocity consistant with ball ammo. The very slight change in weight as the tracer compound burns would not have a significant effect on trajectory. It could have an effect on group size, but again, I would think only a slight effect.
The "cup" in the base of the bullet holding the tracer compound would act like a very broad nozzle, but only to a very small extent. I doubt it there would be a measurable difference in velocity outside of the normal shot to shot variation.
Often tracer bullets are not lighter than ball, they are longer for the same weight. That way they obtain velocity consistant with ball ammo. The very slight change in weight as the tracer compound burns would not have a significant effect on trajectory. It could have an effect on group size, but again, I would think only a slight effect.
Mike Irwin
Staff
In my younger and stupider days, a friend and I pulled the bullets from some tracer rounds and ignited them with a blow torch.
There was absolutely no "rocket effect" of any kind, just a very bright glow that lasted maybe a second.
Most tracer compounds use phosphorus, magnesium, and heavy metal salts that add color to the trace.
There's nothing in the trace compound that can produce the volumn of gas that would be required to give a bullet a boost.
There was absolutely no "rocket effect" of any kind, just a very bright glow that lasted maybe a second.
Most tracer compounds use phosphorus, magnesium, and heavy metal salts that add color to the trace.
There's nothing in the trace compound that can produce the volumn of gas that would be required to give a bullet a boost.
couldn't you pull a tracer round..... rig up some very low friction rail to guide it and ignite the tracer compound??? If the projectile moves, it surely adds velocity, if it does not; well... I guess it wouldn't then. Seems like that'd work to show any real gains in velocity. You could even hang the projectile from a string with the centerline of the bullet parallel to the ground, ignite with an open flame and see if it moves.... at all?
Tom
oops... didn't read. Guess Mike has already done it
Tom
oops... didn't read. Guess Mike has already done it
Double Naught Spy
New member
My guess is that the heat produced by the burn of the tracer does result in unchanneled and hence uncontrolled expanding gasses flying off the back as it spins at some 248,000 rpm (3100 fps with 1:9 twist) which then results in the reduced accuracy as the slipstream is disturbed in a non-uniform manner, but not an increase in velocity.
I understand the whole "nozzle" thing because when I was younger and into model rockets, I used to pack my own engines. The thing of it was that the large engines did require a clay nozzle for added thrust, but the smaller ones didn't because the ID of the small engine was small enough to provide enough thrust to make the rocket fly even without a nozzle. I was just thinking a tracer bullet might have the same effect and I just thought of something too. There is a starting fire composition that burns pretty violently and WILL make added thrust. Like I said, there's lots of different tracer compositions out there and all have different burn rates.
Anyways, thanks for the responses guys. Maybe someday we will have rocket propelled finned 12 gauge slugs. Now that would seriously rock.
Anyways, thanks for the responses guys. Maybe someday we will have rocket propelled finned 12 gauge slugs. Now that would seriously rock.
Rangefinder
New member
Too late... There already are fin-stabilized 12 ga. grenades (not self-propelled though--doesn't need it).