Requirements for Replacement of Currently Issued 5.56 M-855 and 7.62 M-80.

[LR1955]

Guys:

OK -- here you go.

1. State the requirements for a new design of service rifle ball ammunition that may replace the currently issued NATO 5.56 M-855 Ball and 7.62 M-80 Ball.

In order to define a requirement you need to find documented evidence of the shortfall of the currently issued ball ammunition or mission needs statements that have a signature from a 0-6 or above who is or was in a Command position at the time of the document. An easier way to do it is to see if Benning or USSOCOM have created such a requirements document.

So, instead of arguing over the Hague Conventions of 1899 time better spent would be in determining if any requirements exist and if not, figuring them out first and then getting into yaw and other problematic issues of terminal ballistics.

Any takers?

LR1955

[stanc]

Gene,

I doubt that such a requirements document exists. Presumably you don't know of one, either, or I expect you'd have mentioned it before.

In the absence of a requirements document, the only available course of action (IMO) is that being taken by Tony and other like-minded individuals: Attempt to develop a "better mousetrap" and put it in front of the decision makers.

Stan

[LR1955]

Gene,

I doubt that such a requirements document exists. Presumably you don't know of one, either, or I expect you'd have mentioned it before.

In the absence of a requirements document, the only available course of action (IMO) is that being taken by Tony and other like-minded individuals: Attempt to develop a "better mousetrap" and put it in front of the decision makers.

Stan

Stan:

I am not sure if anything exists but one thing for sure is that before embarking on some sort of bullet / cartridge design that there must be a set of requirements for the same.

I believe three factors are already identified. These are penetration of intermediate barriers, lethality, and effective range.

Start with these three factors and from there one goes into statements of what is absolutely required and what is desired. Other factors will arise but can be dealt with as long as the basic requirements are clearly stated.

So, someone define the barrier material, lethality, and effective range.

LR1955

[warped]

Well, we know the M855A1 is a dismal failure, over pressure, dirty and eats bbls in 4k-5k rounds.

[Tony Williams]

A few weeks ago someone asked me to do this. So this was my first-draft shot at it:

OUTLINE SPECIFICATION FOR A LIGHTWEIGHT HIGH-PERFORMANCE SMALL-ARMS CARTRIDGE

The problem

1. Combat experience in Afghanistan has revealed that 5.56x45 NATO ammunition has insufficient range for at least half of the small-arms engagements, and suffers from poor barrier penetration and unreliable terminal effectiveness even within its range.

2. Weapons chambered for the older 7.62x51 NATO ammunition are therefore seeing much more use, but while this ammunition is effective it is heavy and generates high recoil.

3. The aim is to design a cartridge or cartridges which are able to match the long-range performance of 7.62x51 with significantly less weight and recoil while being superior in penetration and terminal effectiveness to the 5.56x45 at any range, therefore enabling both existing rounds to be replaced by one.

Performance Requirements of a New Cartridge

4. To replace the 7.62x51 a new cartridge needs to achieve the following:
- to match the retained energy, vertex height and wind-drift performance of the 7.62mm M80 ball round at 1,000 metres
- to equal the barrier penetration performance of the 7.62mm M80 in terms of overall penetration of a range of media while maintaining its trajectory ("blind to barriers")
- to exhibit rapid and reliable yaw on impact with ballistic gel representing a body, ideally commencing within 50mm of penetration and completing bullet upset within 250mm
- compared with the M80, to reduce the weight to 80% (assuming similar materials) and to reduce the recoil energy in a similar rifle to 60%

5. To replace the 5.56x45 a new cartridge needs to achieve the following:
- to deliver a substantial improvement at all ranges over the 5.56mm M855 in barrier penetration and trajectory maintenance through barriers
- to deliver a substantial and reliable improvement in terminal effectiveness as measured in the size of the permanent channel created in ballistic gel tests within the 50-250 mm penetration zone, regardless of the bullet angle of yaw on impact
- compared with M855 ammunition, to limit the weight to 160% (assuming similar materials) and to limit the recoil energy in a similar rifle to 200%

Cartridge Design Requirements

6. The standard ball bullets used to achieve the performance requirements must comply with European legal interpretations of the Hague and Geneva Conventions governing military ammunition, i.e. they must be designed not to expand or fragment and any jacket must fully enclose the tip.

7. The standard ball bullets should be made of lead-free materials and be suitable for economical mass production.

8. The cartridge designs should be optimised for use in conventional military magazine-fed and belt-fed automatic weapons, so that existing gun designs can be adapted to use them.

9. The cartridge case design should be suitable for manufacture in a range of materials, including brass, steel and part-polymer.

General Observations

10. To achieve the weight and recoil reductions compared with 7.62mm M80 implies a lighter bullet to be fired at a lower muzzle velocity. To achieve this while matching the energy delivered by the M80 at 1,000 metres requires a bullet which loses velocity much more slowly than the M80. This requires a high ballistic coefficient which, given a lighter bullet, implies a calibre smaller than 7.62mm.

11. Comparisons of existing cartridges with the performance requirements listed above indicate that the optimum calibre will probably lie between 6.5mm and 7mm, with a muzzle energy of around 2,500 joules.

[stanc]

8. The cartridge designs should be optimised for use in conventional military magazine-fed and belt-fed automatic weapons, so that existing gun designs can be adapted to use them.

10. To achieve the weight and recoil reductions compared with 7.62mm M80 implies a lighter bullet to be fired at a lower muzzle velocity. To achieve this while matching the energy delivered by the M80 at 1,000 metres requires a bullet which loses velocity much more slowly than the M80. This requires a high ballistic coefficient which, given a lighter bullet, implies a calibre smaller than 7.62mm.

IMO, the above two requirements may be mutually exclusive. Use of a long, high-BC projectile necessarily implies a short cartridge case, a la 6.5 Grendel. However, such a short case does not seem compatible with either the M27 link or the M249 feed mechanism.

Protestations that "It's only a matter of throwing enough money at it" may be true...or they may be only wishful thinking. At this point, we don't have sufficient information to validate or refute the idea that converting belt-fed weapons to a round like 6.5 Grendel is feasible.

Before putting any effort into designing a bullet, it might be prudent to determine if appropriate metallic links can be designed and fabricated for the cartridge of choice.

[warped]

In reality if it were to be adopted making links would not be a big deal, this is according to a guy that makes all sorts of stamped precision metal parts for automotive and other applications.

If there were a need and profit to be made it would happen.

[JASmith]

Gene,

Thanks for throwing down the gauntlet!!

Tony has a good start on a requirements list to replace both cartridges.

There are some items, e. g., desired trajectory, that may be subject to debate.

As we've discussed in other fora, using a single cartridge to attain all of the objectives for an assault rifle and for a general purpose machine gun is extraordinarily challenging given current technology. Ample precedent exists for multiple ammunition types in existing military cartridges. Can we require a single cartridge, but allow at least two loads? An example would be a comparatively light bullet high velocity round for the rifle, and a heavier bullet long range round for belt-fed weapons.

Also, a testable penetration requirement has been stated in lines 4 and 5 of Tony's draft. The 250 mm of penetration coupled with a yawing bullet establishes a significant permanent wound cavity independent of kinetic energy. This lets us use a different lethality metric than kinetic energy and eliminates a potentially controversial requirement.

[LR1955]

Gene,

Thanks for throwing down the gauntlet!!

Tony has a good start on a requirements list to replace both cartridges.

There are some items, e. g., desired trajectory, that may be subject to debate.

As we've discussed in other fora, using a single cartridge to attain all of the objectives for an assault rifle and for a general purpose machine gun is extraordinarily challenging given current technology. Ample precedent exists for multiple ammunition types in existing military cartridges. Can we require a single cartridge, but allow at least two loads? An example would be a comparatively light bullet high velocity round for the rifle, and a heavier bullet long range round for belt-fed weapons.

Also, a testable penetration requirement has been stated in lines 4 and 5 of Tony's draft. The 250 mm of penetration coupled with a yawing bullet establishes a significant permanent wound cavity independent of kinetic energy. This lets us use a different lethality metric than kinetic energy and eliminates a potentially controversial requirement.

Joe:

I have a few more questions for Tony but can't get to them until tomorrow.

You guys are focused on terminal effects on humans. You have not stated what the intermediate barriers are or at what range the ammunition must penetrate, and then its lethality. The words 'various' types of barriers are not sufficient. Anyone who is designing the ammunition must know exactly what needs to be penetrated and at what maximum range.

Focusing solely on terminal effects is not sufficient for military applications.

So, tomorrow I will summarize what I got from Tony and outline things that must be specifically stated.

LR1955

[stanc]

In reality if it were to be adopted making links would not be a big deal, this is according to a guy that makes all sorts of stamped precision metal parts for automotive and other applications.

True, the process of stamping sheet metal to make links is simple enough, in itself. The difficulty is in designing a link configuration that will not only have the required strength and elasticity, but also correctly fit the cartridge case for proper interface with the feed mechanism.

So far, nobody has presented a disintegrating link design that has actually made for any cartridges of similar dimensions and/or proportions to 6.5 Grendel.

The best I've been able to find are the non-disintegrating links made for the 7.62x39, and the .280 British:

http://iaaforum.org/forum3/viewtopic.php?p=52142#p52142

Can the M249 be modified to work with that type of metallic link? And if it can, would the UK be willing to use it? I doubt very much that the US would, what with being so strongly wedded to disintegrating links, and that might influence a UK decision.

Forgive me for sounding like a broken record on this matter. It's just that if 6.5 Grendel is to be the proposed solution, I'd like to see some hard data to support the idea that converting belt-fed LMGs is actually doable. (Conversion of magazine-fed rifles to 6.5 G has been well proven. AFAIK, conversion of belt-feds has not.)

[JASmith]

...You have not stated what the intermediate barriers are or at what range the ammunition must penetrate, and then its lethality. The words 'various' types of barriers are not sufficient. Anyone who is designing the ammunition must know exactly what needs to be penetrated and at what maximum range...

LR1955

Gene,

It appears that we're members of the same choir!

Looking forward to your more detailed draft specs -- even more, I am eagerly awaiting the opportunity to comment. I've designed or played with a few "barrier" targets for military applications - but none involving small arms. If I recall correctly, there are some standard specs for the 7.62 involving single thicknesses of steel plate.

I also suggested to Tony and Stan in an offline message that the bullet be required to not significantly deform on penetration of bare gelatin. Deformation or breakup after perforating a barrier should be allowed.

I know you have same salient thoughts about trajectory for the assault rifle/carbine. They should be included in the discussion.

Cheers!
Joe

[JASmith]

...So far, nobody has presented a disintegrating link design that has actually made for any cartridges of similar dimensions and/or proportions to 6.5 Grendel...

Stan,

You've just prompted one or two lines in the requirements list. I know that Tony is not wedded to the notion of forcing the new cartridge to be compatible with the M16/M4 family of rifles and is indeed looking at cartridges with overall lengths more like that of the 7.62X51 NATO.

So one line might read something like: "The cartridge shall be capable of operating in modified rifles of ..... (Insert the appropriate class of rifles)"

The second line would likely be: "The cartridge shall be compatible with disintegrating links ... (should allow new designs -- I agree with Warped that we can fabricate links tweaked for almost any cartridge, but also agree with your point that some cartridges are easier to link -- body length being one of the salient factors)"

Cheers!
Joe

[Tony Williams]

IMO, the above two requirements may be mutually exclusive. Use of a long, high-BC projectile necessarily implies a short cartridge case, a la 6.5 Grendel. However, such a short case does not seem compatible with either the M27 link or the M249 feed mechanism.

As Joe pointed out, the requirements do not specify that the existing gun designs in which the round is to be usable have to be those sized for 5.56mm - in fact, I believe that would be an unhelpful restriction.

I am thinking more in terms of the FN SCAR H and MK48 LMG as being the kind of guns which this could be suited for.

[stanc]

As Joe pointed out, the requirements do not specify that the existing gun designs in which the round is to be usable have to be those sized for 5.56mm - in fact, I believe that would be an unhelpful restriction.

I am thinking more in terms of the FN SCAR H and MK48 LMG as being the kind of guns which this could be suited for.

I see. When you wrote, "The cartridge designs should be optimised for use in conventional military magazine-fed and belt-fed automatic weapons, so that existing gun designs can be adapted to use them," I didn't realize you were referring to only two existing weapons.

Yes, the Mk17 rifle and Mk48 machine gun should be easily adaptable to a new, longer cartridge. It seems like that will incur significant penalties in weight and bulk, though.

I think if I were to opt for a longer cartridge, while still keeping minimum size and weight of both guns and ammo, I'd consider resurrecting the 1970's 6x45mm SAW round.

[stanc]

Stan, You've just prompted one or two lines in the requirements list. I know that Tony is not wedded to the notion of forcing the new cartridge to be compatible with the M16/M4 family of rifles...

Actually, now that I think of it, there's a very good reason that he should not be trying to "sell" the armed forces on a 5.56-compatible round.

History (of the smokeless powder era, anyway) tells us that every time the military adopted a new cartridge, they also adopted a new rifle and machine gun to fire it.

But, (except back in the blackpowder days) they have never adopted a new cartridge for the purpose of converting and upgrading old weapons.

Looked at from that perspective, cartridges developed for conversion of existing 5.56mm weapons -- such as 6.5 Grendel and 6.8 SPC -- have virtually no chance of being adopted.