Lets start over: how do you design a GPC?

[cory]

JASmith if we develop 2 interchangeable rounds, one for the LMG and DMs and one for carbines, I believe slightly lowering the BC of the carbine round would result in negligible losses. Just my 2 cents.

[stanc]

I was only using those using those weights to make my point. I do think a heavier bullet like a 130gr makes since in an LMG and possibly DMs too.

I don't disagree. What I question is if it is possible to get anywhere close to 130gr in a practical lead free bullet. This has been discussed ad nauseum on the MG&A forum, and most of the knowledgeable individuals there agree that ~108gr is about max.

Let's say we use a 123gr ball round we can go with a 110-115gr tracer, if we go with a 115gr ball round, we go with 95-100gr tracer. I think you get my point.

Sure. The Swedes did that with 6.5x55 ammo. Their Tracer bullet is 20gr lighter than the Ball round. Even with that much weight difference, the Tracer still looks to be slightly longer than the Ball projectile. And, as I mentioned previously, a lead free Tracer would be longer.

I do think the LMG and rifles should have different weighted rounds developed to compliment the platform. That being said the LMG round will need to function in a rifle and vice versa.

That's technically possible, of course, but who seriously thinks the US and NATO would go for it? The Chinese tried it with 5.8x42, but have since reverted to a single loading. I think the French use 55gr for rifles, and 62gr for LMGs, but that was accidental, not planned. (Besides, do we really want to emulate the French? )

[cory]

I don't disagree. What I question is if it is possible to get anywhere close to 130gr in a practical lead free bullet. This has been discussed ad nauseum on the MG&A forum, and most of the knowledgeable individuals there agree that ~108gr is about max.

That's a good question. You've got my wheels turning Stanc. Let me throw this out there. What's the implications of a lead free bullet that's more steel and less copper, relative to the current common ratios? Could that move us towards the weight we're looking for?

That's technically possible, of course, but who seriously thinks the US and NATO would go for it?...

I'd say the odds are about as good as the US and NATO replacing the 5.56 and 7.62 with a GPC.

I think the French use 55gr for rifles, and 62gr for LMGs, but that was accidental, not planned. (Besides, do we really want to emulate the French? )

What can I say when the French are... No on second thought I can't say it.

Where the French blunder into a good idea. Wait one second that's not a good idea in the 5.56. There's no legitimate reason to use a smaller round in the rifle than the LMG, unless you're going to use 77 SMKs in the LMGs and DMs.

However, in the Grendel it makes a lot of sense assuming we can accomplish a round in the 130gr family.

[JASmith]

Cory,

Concur on going lighter with the carbine round. I will need to revisit some earlier calculations, but they indicated that we could go down to 95 -100 grains in the Grendel and get better hit probabilities out to 300-400 meters in the carbine.

Problem is that time I spend on this is time NOT spent in drafting my share of the second volume of the Grendel reloading handbook. Will need to bow out of the conversation for awhile.

[stanc]

That's a good question. You've got my wheels turning Stanc. Let me throw this out there. What's the implications of a lead free bullet that's more steel and less copper, relative to the current common ratios? Could that move us towards the weight we're looking for?

Steel is less dense than copper, so if you make the bullet more steel, it'll move you further away from your goal of a heavy bullet.

As best I can tell, to get close to 130gr in a boat tail spitzer, it'd have to be made of solid copper. However, that type of construction wouldn't interest the US, Europe, Scandinavia, or anyone else.

[SHORT-N-SASSY]

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.

To those Guests looking in on this general Topic, under various titles the past couple years, and, perhaps, concluding that we're essentially where we were at the beginning of these friendly thought-provoking discussions, I would offer in addition to woohoo's Reply, above, the last four sections of Assault Rifles and Their Ammunition, By Anthony Williams http://www.quarry.nildram.co.uk/Assault.htm: "The Lessons," The Current Contenders," Lightweight Small Arms Technologies Programme (LSAT)," "Future Options." Do join us, and contribute your thoughts, as we anticipate the future of small arms technology.