The Future of Small Arms

[Uncle Bob]

Fire control again.

Traditionally, the US Army has considered 500 yd (460 m) to be the effective range of a rifle. This is the same for all weapons from the M1903 Springfield to the M16A2. A lot of people have guessed how this might have been determined from terminal effect or circular error probability, but none really match up.

Looking at a few old texts like Hatcher's Notebook and a turn-of-the-century musketry manual convinces me that the old-timers were smarter than that. A study of the trajectories of all three rounds (30-06, 7.62x51, and 5.56x45 shows some similarities.

At 500 yds a 5 mph error in wind estimation leads to a 12-14" error (ok, 18" for a 5.56mm), or about the half the width of a sillouhette target. Likeways if you set the sights 100 yd off at 500 yds or closer (ie, 400 or 600 yd when the real range is 500 yd) you still barely stay on the torso (18-22" drop) of a sillouhette target.

So for a target at 500 yd or less a skilled marksman who judges the wind to within 5 mph or less and the range to 100 yds or less still ought to get a solid hit. Even a telescopic sight won't change that much.

So the limit is the limit of the mk 1 eyeball, not the hardware.

 

[TheBrain]

"You'd think that, but that turns out to not always be the case. One can design rounds that penetrate hard armor, but become unstable and tumble in tisue. The two media are distinctly different (solid vs. liquid-like). The current US military M855 round is designed to defeat light armor, and yet it still tumbles in tissue."


When was the M855 introduced? I remember reading an article awhile back with an US Army Ranger citing alot of instances in Somalia where the hits from the 5.56 didn't produce rapid incapacitation.

 

[Uncle Bob]

It is a bit of a mystery. The M855 "greentip" was introduced about 1980 and test conducted in the 1980s indicated that the bullet yawed and fragmented like the M193.

Reports of failure to stop from Somalia were largely discounted, but new reports from A-stan and Iraq have cause the M855 to be retested, New production M855 often do not yaw and start to break up until after 8" (20 cm) of penetration. It is believed that a trivial change in manufacture is responsible.

 

[jfwking]

Originally posted by Corejob:
</font><blockquote>quote:</font><hr />Originally posted by Captain Jonah:
Re Flechettes. Reducing size and increasing speed of projectile to penetrate armour. Ok so you have a round that will penetrate Class IV body armour and the odd passing brick wall. The human body (bones aside) is considerably less solid that a wall. If the round is stable on impact you have a round that will make a small and very painfull but not debilitating flesh wound.

You'd think that, but that turns out to not always be the case. One can design rounds that penetrate hard armor, but become unstable and tumble in tisue. The two media are distinctly different (solid vs. liquid-like). The current US military M855 round is designed to defeat light armor, and yet it still tumbles in tissue. The problem is that lethality is effected because energy is lost defeating the armor

</font>[/QUOTE]However I'm not talking about bullets but the flechette rounds which as reports say cause minimal tissue damage as they pass through a body.
Flechettes are stable on impact and keep penetrating which means against soft targets they will go straight through. Modern bullet design can make rounds that fragment and tumble in a body with or without penetrating armour. The problem with these bullets is they are unable to penetrate above a certain armour level which leads back to the bullets bouncing off problem.

There is still a lot of debate about how big smart HE projectiles need to be. Many consider 20mm too small, but it's really only too small if you are expecting 400mm performance. If you get within a couiple of meters, and airburst, 20mm may prove to be just fine.
[/QUOTE]

If you can get the accuracy with 20mm then its fine for the job, 40mm is really for close hit kills. As soon as we start fielding anything close to smart weapons I expect to see personal ECM (at least in some form or only on the PA) to counter it. Leading back to 40mm to get a near miss which still does the job.
PS Anyone shooting at me with a man portable 400mm grenade can have the terrain, I'm leaving

 

[womble]

quote:
Bullpups have several disadvantages over conventional firearms. Inability to use with the off hand (in the case of weapons that eject a case) is a bif one,

</font><blockquote>quote:</font><hr />Okay, why would it be any different? Why is putting an ejection port left vs. right any different in a bullpup?

</font>[/QUOTE]The ejection port in a bulpup format weapon is right back near the user's face, so throwing hot brass out the side means that shooters wil be reluctant to fire with the port pointing at them. There is, however, at least one bullpup weapon which ejects vertically downwards. Of course this problem disappears with caseless ammo, since there's no casing to eject. The G11 has a hole below the rotating bolt so that unfired caseless rounds just drop out as it cycles.

 

[Uncle Bob]

OICW/SABR/XM29/XM25
It is now firing a 25mm round, a low velocity cartridge with the warhead of a OCSW/XM307. This warhead is amost the mass of a 40x46SR (M79, M203 "blooper") and with an electronic fuse may actually have a bigger payload. And they are talking about actively adjusting the priming to modify the "footprint", like the French PAPOP.
Also the biiger projectile will make it a formidable platform for less-lethal warheads.

Bullpups...The FN F2000 ejects the spent shells forward out a tude, and, if it works, is likely the way to go.

Flechettes... I don't think spaced armor will help much unless the spacing is so wide that it will be too bulky for body armor.

When flechettes were developed in the 1960s, and even the Steyr flechettes of the early 1990s, terminal effects were not well understood. AFAIK no-one has designed a flechette to yaw violently, even to break into 2-3 pieces, all we know is that past designs did't.

 

[kaladorn]

How exactly does a 25mm grenade have the warhead of a 40mm? Sacrifice of range or fragmentation? If the round is smaller, how do you get the same bang?

Forward ejection isn't too bad. Neither is down.

And Bob, I would not, per se, say that the limit is the mark I eyeball. I mean, in 'deliberate' shots, yes. In ones that tend to happen, fast snapshots, then it really is the ability to correctly align the weapon fast enough that is the factor.

But if you had a sight that let you project a dot on your target (a la laser sight), and then just trigger the weapon saying "shoot him there", that might be kinda handy. (Of course, your sighting system would need to make the dot visible at range).

 

[mike wightman]

Bullpups...The FN F2000 ejects the spent shells forward out a tude, and, if it works, is likely the way to go.
Thanks for bringing up the FN F2000 Uncle Bob. Is there any technical reason why it couldn't have been designed with a top mounted magazine like the ones on the P90 and G11?
I realise for standardisation purposes it has to accept the NATO standard 5.56mm magazine, but if that weren't an issue could a 5.56mm version of the P90 be built or is the feed system not scalable up to that calibre?

 

[Andrew Boulton]

But if you had a sight that let you project a dot on your target (a la laser sight), and then just trigger the weapon saying "shoot him there", that might be kinda handy. (Of course, your sighting system would need to make the dot visible at range).

Better to have it projected onto a HUD.

 

[Todg]

Originally posted by kaladorn:
As to Bullpups, I can see the ejection issue. Of course, if you went with a caseless projectile, this might not be an issue. Same with Gauss. I was wondering why it would be harder to build one to eject left or right, but I see what you're getting at. Of course, I've a friend with a scar down his back from a throw-forward ejection on the FN (went inside his combat shirt, and he had his pack on and was wearing a gas mask and was in a smoke screen at the time). So shell ejection can cause some kind of hazard at the best of times. I'd think 'out the bottom' ejection might be the answer.

Bottom ejection is used by the Steyr ACR, but it has a very unique method of operation. The New FN2000 uses forward ejection, where the spent case comes out a tube over the barrel - a very neat solution to the ejection problem. One of the limiting factor of bottom ejecttion is case length. With conventioal operation, it's hard to have both the magazine and the ejection port on the bottom of the rifle.

Naturally, caseless ammunition solves this whole problem.

The thing about Gauss weapons is you'll need long barrels to allow length for the accelerator to do its work. In this case, a bullpup configuration may be necessary just to maintain reasonable barrel lengths.

We really don't know this. Chemically powered weapon benefit from longer barrels because there are limits to the expansion rates of product gasses and the longer the gasses can push the projectile the (generally) higher velocity you get.

This may not be the case with EM weapons. It's going to be the total EM forve applied to the projectile that matters, whether isd a lower force applied over a longer period or a larger force applied in a shorter period. There no reason why EM weapons could have very short barrels and achieve the same velocities provided a suitable EM force is applied.

The type of system used will also probably be a factor. The canonical gauss weapon is a coilgun, but it turns out it is a lot easier to make high velocity weapon using railgun technology. One can hardly blame the authors. When Traveller was originally published, coilguns were a staple of science fiction, but few outside of the defense research agency or certain areas of academia had ever head of the railgun.

Whether the coilgun or railgun becomes the basis of EM small arms remains to be seen. Advanced continue in both areas.

 

[Todg]

Originally posted by Uncle Bob:
It is a bit of a mystery. The M855 "greentip" was introduced about 1980 and test conducted in the 1980s indicated that the bullet yawed and fragmented like the M193.

Reports of failure to stop from Somalia were largely discounted, but new reports from A-stan and Iraq have cause the M855 to be retested, New production M855 often do not yaw and start to break up until after 8" (20 cm) of penetration. It is believed that a trivial change in manufacture is responsible.

Thanks, Uncle Bob.

It should be further pointed out that a more powerful cartridge like the 7.62x51mm isn't the solution everyone seem to think it is. With the current ball ammunition, the 7.62 is likely to just go straight through the target, doing very little (comparative) damage. A different bullet would naturally alter this. Even so, when dealing with a drug using opponent, and rifle can prove to be ineffective.

 

[Todg]

Originally posted by Captain Jonah:
However I'm not talking about bullets but the flechette rounds which as reports say cause minimal tissue damage as they pass through a body. Flechettes are stable on impact and keep penetrating which means against soft targets they will go straight through.

See my original comments about flechettes. There has been exactly one report that seriously questions the lethality of flechettes based on actual performance in the field (by Dr. Martin Fackler). This study was based on the performance of flechettes from artillery rounds[/] used during Vietnam.

There has been no published study (at least in the civilian press) of how rifle[/] flechettes perform, either in ballistic gelatin or human tissue. Supposedly, Steyr did perform ballistic gelatin tests with their ACR and reported a high level of effectiveness. However they have not published any detailed reports in the public press, so such rumors much be taken with a very large grain if salt.

We do know that the probem with flechettes is that because they are fin stabilized and the fins work just as well in tissue as they do in air. We also know that there are ways to manufacture flechettes so that they break up or bend after impact. Winchester used an annular groove on the flechettes they loaded in the XM258 shotgun shell. The groove cause the flechetted to break into at least two pieces and become unstable in tissue without effecting its armor piercing ability.

Differential heat treat can also yield flechettes that have good penetration but which tend to bend easily when tarnsiting media (as in penetrating tissue) at high velocities. Such distorted projectiles would create wound tracks proportional to their length as they travelled through tissue, and as flechettes are generally much longer than conventional bullets, one can easily see the impact on lethality.

All that is required to make high velocity flecettes extremely lethal is to get them to bend or break after entering tissue, something that looks relatively easy to achieve. Whether such distortable for frangible rounds wilkl be acceptable to the American public or the international community is another matter. Certainly, such concerns will have little or no impact on the Imperium.

 

[Todg]

Originally posted by Uncle Bob:
When flechettes were developed in the 1960s, and even the Steyr flechettes of the early 1990s, terminal effects were not well understood. AFAIK no-one has designed a flechette to yaw violently, even to break into 2-3 pieces, all we know is that past designs did't.

Actually, Townsend Industries produced a flechette for Winchester's experimental XM258 shotgun round. It has a single annular groove and would break up into two or more pieces. Obviously, such a groove would have profound effect on the ballistics of a rifle flechette, but it certainly suggests a rather simple method of making the flechette relatively lethal.

 

[Uncle Bob]

Originally posted by kaladorn:
How exactly does a 25mm grenade have the warhead of a 40mm? Sacrifice of range or fragmentation? If the round is smaller, how do you get the same bang?

The warhead of a 40x46SR is very short, almost spherical. The 25mm has a longer, more streamlined warhead that weighs a little less (IIRC, 90 g vs 110 g). A lot of the mass in the 40x46SR is a rather inneficient mechanical fuse so the 25mm with electronic fuse has a bigger bang.

Being more streamlined helps, but I doubt the max range will go much over 500m (vs 800m? with the 20mm).

Forward ejection isn't too bad. Neither is down.

But I have this image of yellow-brown sausages squirting out the hole, *plop*, *plop*, *plop*

And Bob, I would not, per se, say that the limit is the mark I eyeball. I mean, in 'deliberate' shots, yes. In ones that tend to happen, fast snapshots, then it really is the ability to correctly align the weapon fast enough that is the factor.

You misunderstand me. My point was that for a century the US Army has defined the "effective range" of rifles not by the weapon's accuracy or ballisticss but by the fire control. And that fire control is the "mark I eyeball" backed up by the skill of the soldier.

But if you had a sight that let you project a dot on your target (a la laser sight), and then just trigger the weapon saying "shoot him there", that might be kinda handy. (Of course, your sighting system would need to make the dot visible at range).

Ah, but at range the bullet drops and the dot doesn't. Unless you rig a laser rangefinder to move the dot to compensate, at which point the fire control again defines the weapon.

 

[justacaveman]

Explosive flechettes?

Possibly manufactured almost entirely from a high density explosive, and fitted with a armor-piercing tip?

 

[Todg]

Originally posted by Sigg Oddra:
Thanks for bringing up the FN F2000 Uncle Bob. Is there any technical reason why it couldn't have been designed with a top mounted magazine like the ones on the P90 and G11?

The feed of the G11 was the result of the mechanism for dealing with obturation problems. The G11 cartridge is relatively short, unlike th standard 5.56x45mm round. The P90s feed system is also best suited for relatively short cartridges.

As an aside, the P90 system is not new. The sytem was invented by John Hill of Houstan, Texas and patented in 1952. Hill used it in a 9mm submachinegun of his own design that never made it past a few prototypes.

The main benefit of the Hill feed system is compactness. It has several disadvantages. Magazine changes are slower and the magazibe must be carefully inserted to insure everything is in propery. This is considered acceptable because the P90 is not meant to be a frontline combat rifle, but rather a weapon for people like drivers, cook and other support personnel who's main job is not combat.

Having fired the P90 at our annual Albany machinegun shoot (an paying a dollar a round for the privelige) I can say that I would not care to have to swap out magazines under fire and where the adrenaline is making and fine motor control next to impossible. It is far easier to just ram a magazine up into the mag well. In that respect, the M-16 is superlative, easier and faster than even the AK.

 

[Todg]

Originally posted by Uncle Bob:
But if you had a sight that let you project a dot on your target (a la laser sight), and then just trigger the weapon saying "shoot him there", that might be kinda handy. (Of course, your sighting system would need to make the dot visible at range).

Ah, but at range the bullet drops and the dot doesn't. Unless you rig a laser rangefinder to move the dot to compensate, at which point the fire control again defines the weapon.

Good points all. Not to mention that you probably don't want any kind of sighting system that actively projects anything.

Ever looked at a laser with STANO gear? You can see the beam rather clearly. If you use a laser pointer, the bad guys will be able to trace the line right back to you.

Not good.

 

[Todg]

Originally posted by LordRhys:
Explosive flechettes?

Possibly manufactured almost entirely from a high density explosive, and fitted with a armor-piercing tip?

Well, for a start, flechettes are really light. The XM110 and XM645 flechette rounds both has a 10.2gn flechette. Now figure that you have to have some kind of detonator, which is going to cut into the payload (never mind having to manufacture uch a puny device). Is it even going to be worth it to bother?

Besides, get an inch longe flechette to start tumbling or hooking in tissue, while moving at 1500 m/s and you won't need explosives.

 

[Todg]

So far the discussion has only focused on the rifle, and already we have identified an number of problems and solutions to improve the performance of the weapon.

If you opt for the bulpup design, forward or bottom ejection takes care of the primary complaint about 'handedness'. Caseless ammunition eliminated the problem all together. While there seems to be a certain advantage to having a 'weight forward' weapon for snap shooting, it occurs to me that there is no reason one couldn't design a slightly suzzle heavy bullpup to address the issue.

There remains a concern about magzine changes with bullpup rifles, but this could be addressed either by using some kind of 'ammunition casette' to make changes less frequently required, or by using an alternate feed system like that of the G11 that allows the soldier to reload without awkward manipulations of the weapon.

As far as hit probability, I have alread suggested that a high ROF burst will improve the likelihood of first round hit. Such a weapon would require a projectile with relative low recoil to minize duspersion. Ideally, the weapon would have some kind of a computing gunsite that would compensate for drop, and also make aiming easier when snap shooting. Alternatively, if the projectile is fast enough, wind drift and bullet drop will be negligeable at combat ranges and no compensating sight will be required.

Provided the flechette can demonstrate the reuired lethality, it seems to be the ideal projectile. It's low madd andlow coefficient of drage means low recoil and very little loss of velocity over combat ranges. It can be driven at very high velocities meaning that the shooter need not compemnsate for bullet drop or wind deflection over the same ranges. It's main disadvantage is that it is long, requiring a suitably long cartridge.

 

[mandelkubb]

Just 2 quick comments:

1. If you're expecting to meet a mechanized enemy, your anti-armor weapons determine at what range you can fight. This is typically below 200 meters for hand-held light anti-armor weapons.

2. Many bullpup weapons are adjustable for right- or leftside ejection. But this isn't something one would do when coming up to a corner from the "wrong" side.