Lets start over: how do you design a GPC?

[JASmith]

I listened to a discussion by Bill A. awhile back that helped illustrate Stan's concern. Paraphrasing:

• The current 5.56 ball projectile started out being a rather accurate and reasonably well streamlined bullet.
  
  
• The specs written by the government, however, allowed the manufacturer to relax the dimensional tolerances of several key features to allow for minimum cost fabrication.
  
  
• This they did, resulting in increased profits and a comparatively inexpensive bullet that meets minimum performance standards.
  

My take away:

1. We will get what we pay for.
   
2. Comparing the best shaped and finished 6.5 slug against the M80 is indeed an apples to oranges comparison.
   
3. Make the comparisons between comparable bullet types, e. g., a 150 gr .308 Sierra Matchking for for the 'super M80' and your favorite 6.5 SMK or your favorite 6.5 Lapua against the 150grain-class LockBase, and so on.
   
   Folks have done this off and on. My own assessment suggested that the Grendel still fares well, just not as dramatically as one might expect with a 144 gr Lapua vs the standard M80.
   

[mongoosesnipe]

If we merely wanted to out perform the 7.62 NATO, the 260 Rem (6.5x51) does that now using the same case. The 260 Rem might be the starting point for comparisons. Then the process would be creating a smaller case that has similar performance. One might want to have a bullet that is similar to the M80. Maybe a FMJ lead core for comparison tests.

Also there is a need to have something other than a brass case as it is just too expensive to leave on the battlefield. So part of the design is a plastic (polymer) case.

polymers melt in hot chambers which causes problems, at least that was the problem with past attempts maybe some new wonder polymer is in the works...

aluminum is not suitable in high pressure application as it has a tendency to fail if i recall they tried aluminum high power rifle cases in the 50s it didn't work out

titanium cost more than brass beyond the fact that it is difficult to work with...

steel works and is cheap but its it can be harder on equipment

[SHORT-N-SASSY]

[SIZE="3"]Just a dash of light-hearted humor, in this otherwise serious Discussion, if you will.

Reviewing the Replies to this Thread, as well as the two related Threads, Military Round Comparisons and Third Generation Battle Rifle, I'm reminded to a couple of cartoons I came across, recently (http://www.cartoonstock.com/directory/i/..._gifts.asp): Image 1, "Innovate, or die," is relevant to most industries, today --- the Electronics Industry, an outstanding example, while Image 2, "Your proposal is bold and innovative, but we are a traditional corporation. I would prefer changes like the ones we've tried before," certainly is true, here, and in the gun industry, as a whole. And, I think the Objections, in the "Objections and Responses" Section, at the end of Tony Williams' comprehensive web article, The Case for a General-Purpose Rifle and Machine Gun Cartridge (GPC),, for the most part, represent yet another example of this "traditional" (read: brickwall) mindset. [/SIZE]

[LRRPF52]

Just a dash of light-hearted humor, in this otherwise serious Discussion, if you will.

Reviewing the Replies to this Thread, as well as the two related Threads, Military Round Comparisons and Third Generation Battle Rifle, I'm reminded to a couple of cartoons I came across, recently (http://www.cartoonstock.com/directory/i/..._gifts.asp): Image 1, "Innovate, or die," is relevant to most industries, today --- the Electronics Industry, an outstanding example, while Image 2, "Your proposal is bold and innovative, but we are a traditional corporation. I would prefer changes like the ones we've tried before," certainly is true, here, and in the gun industry, as a whole. And, I think the Objections, in the "Objections and Responses" Section, at the end of Tony Williams' comprehensive web article, The Case for a General-Purpose Rifle and Machine Gun Cartridge (GPC),, for the most part, represent yet another example of this "traditional" (read: brickwall) mindset.

The brickwall is coming from the military, or elements within the military, dating back to post-Great War with the .276 Pedersen experience. That was actually driven by the Army, where they had determined that the .276 Pedersen would be the new service rifle cartridge, until MacArthur squashed it.

Then we had a similar thing happen with the 7.62 NATO vs. .270 and .280 Enfield. US Army Ordnance Corps couldn't put the .30 cal booze bottle down, when offered some nice Gin from England in the 1950's.

Since the 1950's, we have stockpiled 7.62 NATO to the point that we have 11yrs of it at current demand, as well as 5.56 NATO. If a unit properly tailors its TO&E for the AOR it's in, 5.56 and 7.62 NATO complement each other quite well at the Squad and Platoon levels. Using one caliber exclusively has been proven to be a failure when it's tried like 7.62 NATO M14/M60 system, and 5.56 M16/SAW system in Afghanistan, although you do have 7.62 belt-fed weapons at the Platoon level.

The more you look at this with a clearer picture, the more you realize it's a TO&E and training issue, not a caliber issue. Sure there are more ideal calibers that would work really well in certain AOR's. I know I would rather carry a 16" Grendel than a 16" 7.62 NATO SASS, because I can kick-in doors with it, and reach out to the same effective range as a 7.62, with 50% of the recoil, and more ammo capacity for less weight on my gear. I would still need the logistics footprint to support it though.

[woohoo]

I don't see how it is rocket-surgery, you make a long pill with good aerodynamics, shove it hard, and you are made in the shade. Only way to get that work done is with a short fat case within the constraints of the lowers we have. I just don't see how there is more than one way to do it.

More than one way, at some point there will be a new platform because existing platforms aren't strong enough or big enough for larger cases that a true GPC will need . A green high BC bullet may be the toughest problem to solve. Could be less BC, more speed, longer smaller dia case with longer action length or longer same dia case with longer action length.
Less weight and recoil than the 308 but beat the 308s exterior ballistics with military LIKE projectiles.

[KentuckyBuddha]

Green and that will meet the agreements we have made in the Geneva Convention will be a fundamental difficulty in accomplishing that design for sure, but if we are to keep the M-16/M-4 lower...you have to have a long pill and a short fat case to make the long pill possible. No?

[stanc]

Green and that will meet the agreements we have made in the Geneva Convention will be a fundamental difficulty in accomplishing that design for sure...

The latter is no problemo. We have a JAG who has demonstrated he will approve virtually any bullet design the military wants to use. Examples:

- Sierra MatchKing hollow point bullet (7.62 M118LR, 5.56 Mk262)
- Barnes TSX expanding hunting bullet (5.56 "Optimized")
- ATK SOST expanding, fragmenting hollow point bullet (5.56 Mk318, 7.62 Mk319)

...but if we are to keep the M-16/M-4 lower...you have to have a long pill and a short fat case to make the long pill possible. No?

Depends on the bullet diameter. AR Performance developed a 6x41mm round using a slightly shortened SPC case that could be a potential candidate to upgrade 5.56 weapons.

Of course, there is no requirement to stick with the M16/M4 lower.

[KentuckyBuddha]

True, there is no requirement to keep the lower...but there is always the desire to save a few bucks, and reduce the need for new training and new components/parts for as much as you can.

The JAG folk said that was kosher as long as we were not shooting at Geneva Convention signatories no? Besides one JAG guy might say this the next might say that...next thing you know you are sitting in a box in the Hague or worse you are like those German soldiers at Malmedy, Belgium in the winter of '44 (the were just lined up and shot in the field for wearing the opfor uniform). I knew about the SOST (and I have some) but I was not aware the others were cleared.

[stanc]

The only JAG ruling I have personally read is the one giving the okay to use Sierra MatchKings. It declared SMKs lawful for use against any opponents, whether signatories or not.

Yes, a future JAG could render a different ruling. Up until 20-plus years ago, only FMJ bullets were lawful for combat.

[KentuckyBuddha]

Sadly, there is no Supreme Court of JAGS where the precedent is established law. Kinda makes it hard to be a soldier these days I reckon. But, yhea I get the reasoning...we had a deal with those countries and these lot were not part of it. Though to be completely Boy Scout about it, I really don't see the greater humanity of being shot with a FMJ versus a polymer tip or SOST. If I were picking, and hopefully I never will be, I would pick varmint grenade to the dome for sure, but I am sure there is a very good reason nobody asked me. : )

[stanc]

Sadly, there is no Supreme Court of JAGS where the precedent is established law. Kinda makes it hard to be a soldier these days I reckon. But, yhea I get the reasoning...we had a deal with those countries and these lot were not part of it. Though to be completely Boy Scout about it, I really don't see the greater humanity of being shot with a FMJ versus a polymer tip or SOST. If I were picking, and hopefully I never will be, I would pick varmint grenade to the dome for sure, but I am sure there is a very good reason nobody asked me. : )

Heh, heh. Yeah, a case could certainly be made that a varmint grenade or other high-lethality, hunting bullet is more humane than FMJ for killing. But, the other side of the coin is that many, if not most, bullet wounds are non-fatal. In those cases, the varmint grenade is far more likely to inflict amputating, very destructive, "inhumane" injuries than (non-fragmenting) FMJ.

To reverse your example, would you rather take a hit to the abdomen or thigh with a varmint grenade, or a slow-yawing, non-fragmenting, 7.62x39 M43 round?

[KentuckyBuddha]

I think your point is better at the extremities, but if the shot were going to kill me...hitting the aorta or iliac arteries (or even the femoral triangle) it probably isn't going to matter much as both options are going to have a devastating cavitation pattern and put you down and out fast (at least in geological terms). If you have a lateral injury to the abdomen that is non-lethal either way you are probably going to have peritonitis and either some poor cutters are going to get carpal tunnel with all that bowel resection or....well there really is no way to come out good on that deal...getting gut-shot with rifles is nasty, nasty business.

Maybe if you get hit in the tricep or something where you have a terrible ripping and exploding wound with the varmit grenade versus a clean and cauterized through and through with the fmj round you have a clear choice. : )

:Shudder: I am sorry I brought this up all of a sudden. lol But, it reminds me of a video I found educational even after having studied this stuff for a while.
Cliffs, pistols mostly wound, rifles at a much much higher rate.

skip to a min in to skip intro, and it is 30 min.... but as I said informative but some of it is very graphic...so be warned

http://www.youtube.com/watch?v=tku8YI68-JA

[Tony Williams]

Nammo Lapua has developed a second-generation 5.56mm "green" round using a steel-cored FMJ bullet (matching all Hague/Geneva interpretations) which they claim matches M855 ballistics, yaws rapidly and reliably on impact, and penetrates better.

[SHORT-N-SASSY]

The latter is no problemo. We have a JAG who has demonstrated he will approve virtually any bullet design the military wants to use. Examples:

- Sierra MatchKing hollow point bullet (7.62 M118LR, 5.56 Mk262)
- Barnes TSX expanding hunting bullet (5.56 "Optimized")
- ATK SOST expanding, fragmenting hollow point bullet (5.56 Mk318, 7.62 Mk319)

Thanks for the clarification. Upon a review of the Sierra MatchKing HPBT projectiles used in the 7.62 M118LR and 5.56 Mk262, it appears that the nearly closed tips of those approved designs are identical to the tips of the 6.5mm Sierra MatchKing 123-grain HPBT, the 6.5mm Nosler Custom Competition 123-grain HPBT and the 6.5mm Lapua Scenar 123-grain HPBT.

[stanc]

If you have a lateral injury to the abdomen that is non-lethal either way you are probably going to have peritonitis and either some poor cutters are going to get carpal tunnel with all that bowel resection or....well there really is no way to come out good on that deal...getting gut-shot with rifles is nasty, nasty business.

Maybe if you get hit in the tricep or something where you have a terrible ripping and exploding wound with the varmit grenade versus a clean and cauterized through and through with the fmj round you have a clear choice. : )

Okay, go with that example, then. I know which I'd prefer.

The reason I said abdomen is because of the experience of an old acquaintance, a Marine veteran of Vietnam who was gut shot with 7.62x39 rounds during a firefight. I don't know how much internal surgery he went through, but he survived with only three little pucker scars as a visible reminder.

:Shudder: I am sorry I brought this up all of a sudden.

Yeah. Maybe we should get back to topic. The military will use whatever bullet type they deem appropriate.

[Trooper]

Nammo Lapua has developed a second-generation 5.56mm "green" round using a steel-cored FMJ bullet (matching all Hague/Geneva interpretations) which they claim matches M855 ballistics, yaws rapidly and reliably on impact, and penetrates better.

Tony is there any chance that we are going to see a GPC? Or are we stuck with two calibers that do the mission but with lots of logistical headaches?

How do we develop a GPC, test it, in such a way that the Sergeant Majors at Ft Benning have to notice?

[woohoo]

Tony is there any chance that we are going to see a GPC? Or are we stuck with two calibers that do the mission but with lots of logistical headaches?

How do we develop a GPC, test it, in such a way that the Sergeant Majors at Ft Benning have to notice?

I can tell you they may notice it, look at it, and test it themselves but that doesn't mean it will go anywhere. The cartridge and platform would have to be far ahead of the current system. It must be a big company that can develop a complete system that blows everything else out of the water.
Just goofing off 5 years ago we dropped $40k into testing several different chamber and rifling designs to increase performance. It takes a lot of money to develop, test and PROVE a complete new system.
The problem I see is the military doesn't know what they want. Someone will have to prove their system and then sell the idea to the military that it IS the system they need.
Everyone at the top is going to want what THEY think they need and they will cast a shadow of doubt on every product that they as individuals don't want.
If company "A" does come up with an idea that the mil can actually agree on. The govt will snatch the design and hand it to company "C" to produce.
Sorry for the negative view but it seems that is the way our government works these days. If it was run like a business it would be a totally different game.

[stanc]

The problem I see is the military doesn't know what they want. Someone will have to prove their system and then sell the idea to the military that it IS the system they need.
Everyone at the top is going to want what THEY think they need and they will cast a shadow of doubt on every product that they as individuals don't want.

That pretty well sums it up. The fact is, there have been a multitude of new cartridges developed over the years, many within the military itself. Only rarely does a new round get adopted. (Logically, they can't all be adopted, or the system would be in chaos.)

IMO, to get a GPC into service will require the active support of one or more high level entities, such as 5.56x45 and the AR15 received from the Commanding General of CONARC and others, in the late 1950s and early 1960s. Without such backing, the GPC will go nowhere.

[Guardsman26]

Reading this discussion convinces me that Bill Alexander and the team at Lapua did a truly excellent job with the 6.5 mm Grendel. To package that amount of performance in a cartridge the same length as a 5.56 mm M855 is truly impressive. The point that is well made here is what happens when you mass produce Grendel rounds, need to use an FMJ projectile or fire the round from a weapon with an excessively short barrel: you get a certain amount of performance degradation.

Then there is the need for a tracer, which eats away at case capacity.

Then there is a possible future need for a polymer cartridge, which also erodes case capacity by about 10%.

For all these reasons, giving the Grendel a longer case is the perfect start point for a GPC contender IMO. You don't need a wider case, like the 7.62 mm one, simply a slightly longer version of the existing Grendel 11.3 mm head diameter.

As soon as you extend the Grendel case length, however, you will need a weapon with a longer action length. You need an AR12.5. Once you accept that requirement, then you are on the road to a perfect GPC. The net result is a weapon that is about 1 lb / 500 g heavier than a 5.56 mm equivalent.

But, here comes the good news. When it comes to building a SAW variant, you can actually start with a 5.56 Minimi M249 rather than the 7.62 mm M240. So with the SAW, you can create a much lighter machine gun, but with much greater firepower.

[LRRPF52]

Reading this discussion convinces me that Bill Alexander and the team at Lapua did a truly excellent job with the 6.5 mm Grendel. To package that amount of performance in a cartridge the same length as a 5.56 mm M855 is truly impressive. The point that is well made here is what happens when you mass produce Grendel rounds, need to use an FMJ projectile or fire the round from a weapon with an excessively short barrel: you get a certain amount of performance degradation.

Then there is the need for a tracer, which eats away at case capacity.

Then there is a possible future need for a polymer cartridge, which also erodes case capacity by about 10%.

For all these reasons, giving the Grendel a longer case is the perfect start point for a GPC contender IMO. You don't need a wider case, like the 7.62 mm one, simply a slightly longer version of the existing Grendel 11.3 mm head diameter.

As soon as you extend the Grendel case length, however, you will need a weapon with a longer action length. You need an AR12.5. Once you accept that requirement, then you are on the road to a perfect GPC. The net result is a weapon that is about 1 lb / 500 g heavier than a 5.56 mm equivalent.

But, here comes the good news. When it comes to building a SAW variant, you can actually start with a 5.56 Minimi M249 rather than the 7.62 mm M240. So with the SAW, you can create a much lighter machine gun, but with much greater firepower.

I've looked at the cross-section of the 6.5mm Swede Tracer, and the existing sectional density and bullet profile of 130gr class 6.5mm pills would facilitate the tracer element without impacting case capacity like tracers do to 5.56 and 7.62 NATO. I don't think there's a need to affect case capacity at all really with an LMG using a 2.400" COAL.

A wider case is also a no-go because you just departed from the intermediate cartridge concept and weight parameters, falling into self-loading battle rifle territory-a system that shouldn't have progressed past WWII in my opinion.

If you were with me when I put 4 rounds on-target at 1200yds from my 16" Grendel as fast as I could index the reticle and pull the trigger, I think the words "performance degradation" would evaporate from your perspective on this cartridge in its existing form. That type of performance is currently exploitable by Machine Gunners and Snipers/DM's. A system built around a military projectile with a BC in the low-to-mid .5's G1 is easy to do. I think a 130gr would be the ticket, run at 2500-2600fps. An LMG will have a bolt/chamber/breech built around the cartridge. I still see no reason to increase the case length & weapon weight, especially for a DMC/SASS.