Vented bullets?

[robear]

Saw this on gizmodo.com.    Apparently they're saying that in the time it takes for the vents in the bullet to clear the muzzle to the time the base of the bullet clears the muzzle, the vents will have a 'compensating' effect, reducing recoil. 

This one really has my BS meter pegged.
The manufacturer's website has more words, but less explanation.   It was obviously cut and pasted from a google translatation.

http://gizmodo.com/5865769/the-compbullet-reduces-recoil-with-rocket-vents
http://www.compbullet.com/prodottieng.html

Thought I'd see what the hive mind has to say about this one.

[French G.]

I say horsecrap. They probably feel light because all those bullets are offered are light for caliber standard weights. Equal and opposite reaction, the momentum has already been imparted to the bullet, so absent directional gas porting from a real muzzle brake or comp there will be no change in gun handling if shot against an identical load with a standard bullet. However, good luck finding a 100gr 9mm bullet that's not some crap made for a .380. furthermore, they should be shot just for that website.

[Doggy Daddy]

Nigeria is selling ammo now?

DD

[makattak]

Nigeria is selling ammo now?

DD

Dear Sir/M,
I am Mr.David Mark. an Auditor of a ARMORY OF THE NORTH
INTERNATIONAL,ABUJA
(FCT). I have the courage to Crave indulgence for
this important business
believing that you will never let me down
either now or in the future. Some
years ago, an American Ammunition
consultant/ contractor with the Nigeria National
Ammunition Corporation,
made a contract for VENTED ammunition for twelve calendar
months, valued
$12M.USD (TWELVE MILLION US DOLLARS). On completion,
The
armory sent a routine notification to his forwarding address but got no
reply.
After a month, The armory sent another reminder and finally his
contract
employers, the Nigerian National Ammunition Corporation wrote
to inform the armory
that he died without MAKING A WILL, and all attempts
by the American Embassy to
trace his next of kin was fruitless. I
therefore, made further investigation and
discovered that the
beneficiary was an immigrant from Jamaica and only recently
obtained
American citizenship. He did not decla re any kin or relations in all
his official documents, including his Bank deposit paper work. This
ammuntion total value
amount$12M.USD ( TWELVE MILLION US DOLLARS)is still sitting
in my warehouse as
contracted merchandise. No one will ever come forward to claim
it, and according to
Nigerian Ammunition policy, after some years, the
ammunition will revert to the
ownership of the igerian Government if the
account owner is certified dead. This
is the situation, and my proposal
is that I am looking for a foreigner who will
stand in as the next of
kin to beneficiary, and OPEN a contract abroad to
facilitate the
transfer of this ammunition . This is simple, all you have to do is to
purchase a storage unit anywhere in the world and send me its detail for me to
arrange
the proper ammunition transfer paperwork, and facilitate the
transfer.The ammunition will
then be transfered into this storage unit for us to share
in the ratio of 60% for me, 35 %
for you and 5% for expenses that might
come up during transfer process. There is
no risk at all, and all the
paper work for this transaction will be done by me
using my position
and connections in the banks in Nigeria. This business
transaction is
guaranteed.And the first phase of the transfer will be ($4M.USD)
FOUR
MILLION DOLLARS worth of ammunition as advised by our insider in the armory.If you are
interested, please reply immediately through my personal email sending
the
following details: (1) Your Full Name/Address (2) Your Private
Telephone/fax
Number. Please observe the utmost confidentiality, and be
rest assured that this
transaction would be most profitable for both of
us because I shall require your
assistance to invest some of my share
in your country. I look forward to your
earliest reply.
Yours,
Mr.David
Mark.

[CNYCacher]

http://www.youtube.com/watch?v=2GbS3jNHFf4

[Tallpine]

Newton 

[AJ Dual]

Newton 

How does it work?

[Brad Johnson]

For it to have a braking effect the gasses would have to be discharged at an angle, directed to the rear.  Looks to me like the holes are straight-drilled.  Unless they've figured out a way to change the laws of physics, the claims are BS.

Beside, if you want to reduce recoil by decreasing projectile velocity, wouldn't it be easier (not to mention cheaper and less complex) just to put a little less propellant in the case?

Brad

[Tallpine]

How does it work?

For every action there is an equal and opposite criticism 

[birdman]

For it to have a braking effect the gasses would have to be discharged at an angle, directed to the rear.  Looks to me like the holes are straight-drilled.  Unless they've figured out a way to change the laws of physics, the claims are BS.

No (on the rear-direction), recoil can be reduced by directing the gases at ANY angle away from the direction the barrel is pointing, as due to vector addition, the average gas velocity forward is reduced.  True, angles beyond 90deg allow for the gases to partially compensate for the projectile momentum (hence, recoilless rifles), but if you look at the gas direction on most muzzle brakes (look at pictures of everything from rifles to large braked artillery, in the vast majority of cases, the direction is sideways, even for pepper-pot brakes where it would be trivial to give it backward velocity.

This bullet is still bogus stupid crap and so is the article--rifled barrels do NOT allow gas to escape ahead of the bullet (unless there is something horribly wrong)--that's why bullets are bigger in diameter than the distance between the lands.  Take the 5.56mm NATO, the distance from land to land is 5.56mm, but the bullet is 0.224", or 5.7mm (that why the 5.7x28 and 5.56x45 can use the same bullets, FN measured across the grooves to differentiate the caliber as a marketing ploy...though other countries/manufacturers have done similarly for other reasons.  Since the bullet is as big as the grooves, no gas leaks past it.  The extreme example of bullet sealing is the 50BMG, which has a 0.510 diameter bullet, which is even bigger than the distance across the grooves, as it was designed to achieve perfect sealing by swaging the bullet into the rifling.

Secondly, it takes the gasses (assuming a gas velocity equal to uzzle velocity, and a barrel filled uniformly, which isn't true, as at the instant the bullet reaches the crown, the gas distribution in the barrel is heavily biased toward the breach due to the maxwellian distribution of gas velocity) about a millisecond to leave the barrel in this case (assuming a 20-24" barrel and a 1700-2000fps muzzle velocity.  The effect this bullet is supposed to accomplish (divert gases) can not take place when the lateral ports are exposed, but the base hasn't left the muzzle...which looks to be about 2-3 times the diameter...so an inch (for a 30cal).  Which means the maximum amount of gases that could possibly be expelled (ignoring my next point) is 1/24th...or only a 4% reduction in the recoil due to the gas, which is usually 1/4 to 1/3rd the total recoil, so less than 1% recoil reduction.

Also, for the gas to escape, it has to go through those ports, which are smaller than the barrel, since the flow is going to be sonically choked, the actual amount of gas that can be diverted is less than 1/4-1/10 of the theoretical max in my previous statement, so we are down to 1/10 of 1% of recoil reduction.

However, since it is an all copper bullet of similar shape and L/D to a conventional BTHP, it will weigh less than a conventional lead core bullet (60-80% of original, which is why monometal bullets are either much longer for the same grain weight, or much lighter than conventional for the same size--e.g. 235gr solids vs 300gr conventionals for my 338lapua).  Drilling out the bullet would further reduce the mass, so these are likely 50-60% of a conventional bullet's weight.  THIS is where the apparent recoil reduction is coming from.  Even if the kinetic energy transferred to the bullet remained constant (which it doesn't, as the lighter bullet leaves the barrel sooner, resulting in less energy transfer from the gasses, and bumping into sound speed limits on the gasses for even higher velocities) a 50% lighter bullet would exit 1.414x faster, but have a momentum of 0.707x the original bullet, with a corresponding reduction in recoil (if one assumes the bullet is 75% of the recoil, this would yield a 22% recoil reduction).  In reality, the bullet would not be going 1.414x the speed, but likely 1.2-1.3x meaning the recoil reduction is even more pronounced--but only due to a lighter bullet!

And other problems, those ports are going to cause side-forces and those forces AREN'T (by definition, since the part of the bullet behind them is partially hollow) through the CG, or the center of gyration, they are going to cause increased nutation if there is even the smallest asymmetry of gas floor shape, which would render the accuracy crap.

Overall, on a scale of 1-10 for implied firearm or ballistics knowledge I give this bullet AND the original article a negative 2, which is below the "ring" or "central channel" bullet idea.
However, I do give this concept a 20 on the same scale if their target market is mall-ninjas who reload...which thanks to Darwin is a small market (btw, what happens when powder gets up in there when the loaded cartridge is turned on its side...like you know, normally..and then fired...and the burn front gets to it half-way down the barrel?), and anyone I know that reloads would look at these and have the same thoughts I did...so how do they expect to make money?

[AJ Dual]

These will be the precursor to ram-rocket bullets, that have a hollow cavity all the way through, with a constriction filled with solid propellant, and they'll ignite upon firing and actually accelerate in flight... 

[Tallpine]

The way to eliminate recoil is to build a double barreled gun that fires a bullet in opposite directions with each pull of the trigger.   

[41magsnub]

The way to eliminate recoil is to build a double barreled gun that fires a bullet in opposite directions with each pull of the trigger.   

If you did it right it might even have a fun spinning effect!

[Azrael256]

Did anybody else see Birdman write a dissertation on this, or am I the only one who sees it?

Decaf...

[CNYCacher]

Such is birdman

[AZRedhawk44]

I lurvs our birdman.

He takes something that I mostly kinda sorta grok, most of the time, with an intuitive yet vague understanding...

And quantifies it to the joule, out to 8 units of precision.   With seemingly effortless grace.

[Azrael256]

Yeah, not complaining, just observing.

The thought occurs to me that it might be unwise to ridicule the man who is the most likely of all of us to actually build a giant moon laser.

But seriously: Decaf.

[seeker_two]

Definitely looks like a great way to lower the weight of a novice shooter's wallet.....other than that, I don't see anything useful....

[CNYCacher]

The thing I love about birdman is that he takes exactly what I'm thinking and saves me 5 minutes of typing by posting it for me.

[birdman]

You know, I have been having a crappy week, and reading this thread has really made me feel much better.  Thanks APS, it makes me happy to know my random "I have a few minutes between jobs" treatises/rants are appreciated :)

As for decaf...no, they will find me dead, on top of my giant moon laser, hand clasped around a 20oz (or as my friends call it, the "Marc" size redbull) before I give up my stimulants!  Besides, adderal and massive caffeine is the only way I've found to deal with the fatigue associated with certain medical issues :(

On the other hand...a resting heart rate of 176 is normal right?

[brimic]

I wonder if they whistle?

[coppertales]

It is from Nigera....................aka.................scam........................chris3

[AmbulanceDriver]

You know, I was having a bad afternoon.  Then I read this thread. And then I got to these last two posts....  And started laughing hysterically.  Why???

Because I took this:

As for decaf...no, they will find me dead, on top of my giant moon laser, hand clasped around a 20oz (or as my friends call it, the "Marc" size redbull) before I give up my stimulants!  Besides, adderal and massive caffeine is the only way I've found to deal with the fatigue associated with certain medical issues :(

On the other hand...a resting heart rate of 176 is normal right?

And this:

I wonder if they whistle?

And my brain said, "What, his heart valves?"


'scuse me, i'll be in the corner giggling and laughing uncontrollably for a little while...


ETA:  Now that I'm done laughing, I do have to add that I definitely enjoy Birdman's posts.   Like AZ, he take something that I kinda sorta get on an intuitive level and explains why it would or wouldn't work to the nth degree.  And I always learn something new...

[Brad Johnson]

I wonder if they whistle

And my brain said, "What, his heart valves?"

Given his stated resting heart rate of 176 it would be more of a buzz, I think.

Brad