saving private ryan

[motto]

Beware the tumbling bullet.

Continuing with the theme of bullet behaviour, one of the reasons given in the program for water providing protection from small arms fire is that the water caused the bullet to tumble thus dissipating energy more quickly. A tumbling bullet also makes for far more serious wounds if it strikes a human body so being immersed or partly submerged in water may very well work against you.

The .303 British rifle cartridge went through many changes in its development including hollow point versions often referred to as dum dum bullets. These were later outlawed by the Geneva Convention. The bullet designers went back to the drawing board and ultimately came up with the Mark 7 projectile which incorporates a cunning feature that even most of the users were unaware of. The core of the 174 grain fully copper jacketed bullet was not entirely lead filled, the first 5/16" or so was in fact aluminium or composite material much lighter than lead.

The effect of the plug of lighter material at the front of the bullet was to shift the centre of gravity slightly aft making the bullet less stable if it encountered resistance, ie it was demonstrably more prone to tumble when it struck something instead of continuing straight through leaving a neat round hole.

The Mk 7 Ball cartridge as it is correctly titled was the standard rifle round used by British and Commonwealth forces before during and after WW2. It was produced in the billions and had a nasty little secret.

David

[Mike Cecil]

Interesting Dave, but according to BA Temple (1986) 'Identification Manual on the .303 British Service Cartridge No.1 Ball Ammunition' page 5:

'Contrary to popular belief that this compound core was intended to make the nose light so that on impact the base would try to overtake it and so cause the bullet to tumble, and thus make a more severe wound, it was actually designed to allow the weight of the bullet to be reduced without a corresponding reduction in length. Ballistically, the longer the bullet in relation to its diameter the better, but if the Mk.VII bullet had a solid core its weight would be about 196 grains, or not much less than the previous service bullet, so much of the benefit of the pointed shape would have been lost.'

The only time I ever experienced/observed bullet tumble firing .303 was Mk8Z rounds through a 'semi smooth bore' P14 (Rifle, No.3 MK.1) - much tooooo much velocity for the poor old, worn smooth barrel. By the time they were 50 yards away, they were off course and going sideways through a paper target, leaving a perfect boat-tailed bullet shaped profile. I kept the Mk8Z for my No.4 and No.4T rifles after that!

Mike C

[motto]

What you state is perfectly correct Mike except for two salient points.

One is that for whatever reason the lighter material was placed at the front of the core it does move the CofG back and thus reduce stability. Surely if you wanted to lighten a given projectile by adding a less dense material to the core it would make more sense to place it at the other end and so INCREASE stability.

Second. As far as I am aware. Nobody before or since has felt the need to incorporate a similar feature FOR PURELY BALLISTIC REASONS.

Contrary to your experience Mike, I have on several occasions had Mark 7 bullets strike sideways. Some have even done so after free flight which still puzzles me. The most impressive example was when operating a snap target at Williamstown Rifle Range. The fellow shooting at my target was aiming low and the bullets were striking the parapet first. Four consecutive shots went through the 3x1 inch stick to which the target was attached. All four were clearly travelling sideways and by then the stick was so wonky that I couldn't put it up for the next shot.

Being on the receiving end sure gives you a different perspective.

Cheers, Dave

[Mike Cecil]

Well, Dave, from what you contend in your first point, any round structured with a light weight nose would be less stable and prone to tumble. Yet Observation rounds (like the Brit L11A1 and L11A2, among others) were designed for great accuracy at long range ie very stable in flight, in order to maintain a pseudo-ballistic match to larger calibre projectiles for sighting purposes. These were typically structured with a light weight flash mixture contained within the nose, and a lead slug behind. Same goes for several US 'flash-spotting' rounds and training rounds, and numerous other specialist rounds with various mixtures housed within the tip of the bullet.

Sure, I don't know of another Ball round structured the way the Mk.VII .303 either, but there are plenty of examples of very stable specialist rounds structured that way.

Mike C

[motto]

Terminal ballistics is the bone of contention here, what happens on and after impact. The spotter rounds you mention simply explode and their job is done. The ball rounds job on the other hand has just begun and all it has going for it is its kinetic energy. What it does with that energy determines its effectiveness. If it bores through the target leaving a neat hole then some of the energy is wasted. This is why soft points and hollow points were developed, to impart maximum energy and thus create maximum damage.

Another approach to achieve a similar result is to make the projectile somewhat unstable so as it is quite likely to tumble when encountering more resistance to its path. Why is it so surprising that this course was adopted when not many years before the British military was officially issuing Mk3 and Mk4 hollow point .303 along with the impressive .455 Webley Man Stopper. With its cavernous front end the Man Stopper cartridge was touted as being for use on Kaffirs and Zulus along with the observation that it took 3,000 rounds (of conventional ammunition) to disable a Kaffir.

I refute B A Temples statement as being just his opinion unless documentation or reference material is to hand. The facts seem to speak for themselves.

Dave

[Mike Cecil]

True, B A Temple doesn't provide a reference or an attribution/source for his statement, which forms but a very small part of his well-researched and well received three part guide to .303 cartridges.


Mike C

[motto]

I must admit Mike that research is not my strong point, I merely have an accumulation of information that is not always accurate. The fact is that we may never know the true philosophy behind the adoption of the .303 Mark 7 projectile and its unique construction. Maybe it was simply a wrong headed solution to a perceived ballistic problem, maybe something more sinister. If it was even slightly sinister then without doubt there are people with a keen interest in keeping that knowledge out of the public realm.

We can't believe all we read Mike. You should know that better than any one.

Dave

[Tony Smith]

Originally Posted by motto

Second. As far as I am aware. Nobody before or since has felt the need to incorporate a similar feature FOR PURELY BALLISTIC REASONS.
Cheers, Dave

Unless of course, if you include the line of Ballistic Tip Bullets made by various companies such as Nosler, Hornady, Sierra, RWS, Geco, etc, etc. for the past 50 odd years!

The tumbling of a bullet on impact is not induced by the CoG being towards the rear of the bullet mass, it is induced by a Gyroscopic Effect, where a rotating mass which suddenly decellerates will twist on it's axis. This was also famously apparent in the US M16 rifle, which was described as an "insidious characteristic" of 5.56mm ammunition when introduced. After an outcry over it's "inhumanity" due to the severe wounds it caused (it's a war, go figure!), it was modified by reducing the rate of twist of the rifling in the barrel to reduce the rpm of the bullet in flight, which in turn reduced the tendency to tumble on decelleration of impact. It is certainly not a unique characteristic on the .303 Mk7 Ball Cartridge.

[motto]

Hi Tony

The reason I emphasised the statement FOR PURELY BALLISTIC REASONS was because of the tipped bullets you mention. They are intended for sporting use and the tip is part of the controlled expansion desired on impact. (Animals not being signatories to the Hague or Geneva conventions, this is allowable) As such the tip is NOT there for purely ballistic reasons. These tips are also exposed which is where the ballistic part comes in, they complete the bullets shaping in contrast to that of an exposed hollow point.

I clearly recall the controversy over the 5.56 ammunition .Stability in flight is controllable by twist rate which means that a bullet can be spun too fast with consequences at the end of flight which some believe to be the case with the 5.56 and its relatively short bullet. The development of the SS109 projectile was an attempt to answer deficiencies in performance of the standard bullet.

Basically, as I understand it, the heavy .303 projectile was too good at penetration, the lighter 5.56 not good enough. Different problems, different solutions. You may be able to help me out here Mike. I believe you are familiar with the SS109 story. I also understand that the 5.56 is not performing well against the opposition in Afghanistan despite the improved projectile.

David

[Mike Cecil]

I can add a little: as I understand it, the 5.56 was not performing well at the distances of typical engagements in Iraq and Afgh. US Forces started reaching for the M14 (7.62mm) because of its greater reach and knock-down power. The Aust Army purchased a series of sniper rifles in heavier calibres to cover the intermediate range of engagements incl .338 Lapua. I have a DVD somewhere of a brief given by DMO about the acquisitions.

This was not a new 'problem': the same difficulty of not enough knock-down power was also experienced in SVN in the late 60s.It came up several times in interviews I conducted with veterans of SVN.

It may lead to the adoption a new improved calibre once the F88 fleet reaches LOT (life of type) in 2020 or 2025. Remember that the 5.56 was simply a light game hunting round in its earliest form, not developed from scratch as a military round.

Mike C

[easo]

I did rear somewhere that the US was implementing environmentally friendly "steel core" ammo. It also gives it more penetration at longer ranges.

Easo