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The Case For A General-Purpose Rifle And Machine Gun Cartridge (Gpc)


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#1 Tony Williams

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Posted 02 September 2012 - 0229 AM

I've thoroughly revised my web article which argues the case for replacing both 7.62x51 and 5.56x45 with one new general-purpose cartridge in the next generation of small arms: http://www.quarry.ni... Generation.htm

#2 Chris Werb

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Posted 02 September 2012 - 1259 PM

Wonderful article Tony!

#3 Typhoid Maxx

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Posted 02 September 2012 - 1704 PM

Yup. Brilliant. Not going to happen ;) but a bloody good read, seriously.

#4 Simon Tan

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Posted 02 September 2012 - 1749 PM

Tony...this is so 2008. :P

#5 Rick

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Posted 02 September 2012 - 1912 PM

I am ignorant about small arm ammuntion. How does the AK47 round compare with the above mentioned rounds? Would it make an acceptable substitute?

Edited by Rick, 02 September 2012 - 1913 PM.


#6 Guest_Jason L_*

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Posted 02 September 2012 - 1923 PM

Here we go again...... :P

#7 Tony Williams

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Posted 02 September 2012 - 2038 PM

I am ignorant about small arm ammuntion. How does the AK47 round compare with the above mentioned rounds? Would it make an acceptable substitute?


A short, stubby bullet which quite rapidly loses the relatively low velocity it starts with. The size of the bullet makes it reasonably effective at up to 300m (especially if you use lead-cored Yugoslav ammo instead of the usual steel-cored - it yaws on impact much more rapidly), but it has a rainbow trajectory at long range.

#8 Tony Williams

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Posted 02 September 2012 - 2044 PM

Tony...this is so 2008. :P


Actually, I first worked this out in 1971 (http://www.quarry.ni...k/6.5mm GPC.jpg :P ) but it takes a while to convince the US Army of anything. However, we have the Ehrhart report in 2009, the ARDEC calibre study in 2011, the AMU report in 2012...they are gradually coming to See the LightTM!

#9 rohala

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Posted 03 September 2012 - 0245 AM

Tony Williams, how does the old Mannlicher-Shoenauer 6,5mmX54mm cartridge compare to those? The Greek army used that 6,5mm caliber for decades -and virtually almost all wars fought by Greece- but they went for 7,92mm by the last years of the 30's, partly for supply reasons but, apparently, also because it was seen as weak.

#10 Tony Williams

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Posted 03 September 2012 - 0405 AM

Tony Williams, how does the old Mannlicher-Shoenauer 6,5mmX54mm cartridge compare to those? The Greek army used that 6,5mm caliber for decades -and virtually almost all wars fought by Greece- but they went for 7,92mm by the last years of the 30's, partly for supply reasons but, apparently, also because it was seen as weak.


The main problem with that round was the same as the problem with Italian 6.5x52: they both had heavy, round-nosed bullets fired at a low velocity which had a poor trajectory and tended to punch neat holes through people, doing little damage unless they hit something vital. Given a lighter, higher-velocity spitzer bullet they would have been far more effective - as the otherwise similar Japanese 6.5mm Arisaka demonstrated.

#11 TonyE

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Posted 03 September 2012 - 0633 AM

(sniff) I miss 6.5x55 Krag.Posted Image

#12 Tony Williams

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Posted 03 September 2012 - 0838 AM

(sniff) I miss 6.5x55 Krag.Posted Image


I'm not surprised. A great sniper/sharpshooter/LMG round, but too big and powerful for the assault rifle role.

#13 Simon Tan

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Posted 03 September 2012 - 0946 AM

Tony, I believe the One Round mantra to be flawed. The reality is that yer individual has a finite distance in which he can deliver fire due primarily to training and visual considerations. It does vary but I would use 600m as an extreme limit for point fire. Beyond this, you need either equipment and skillsets that are beyond the infantryman like LR precision rifle training, tripods w. T&E etc.
Ironically the Taliban responded the problem by developing their close and long teams, the former built around the 7.62x39 and RPG to manouevre, close and destroy the enemy, the latter with 7.62x54 as a base of fire. This in turn drove the NATO/ISAF responses.
This is a much more sensible and low risk approach IMO, to essentially have a 5.56NATO and a 7.62NATO replacement. Examples exist of both like 6.8SPC and the .338 Norma Mag on the LWMMG.
The One Round idea brings us back to 7.62NATO, too much bullet or not enough depending on what you are doing.

#14 Ivanhoe

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Posted 03 September 2012 - 1041 AM

Yup. Brilliant. Not going to happen ;) but a bloody good read, seriously.


All the time I was looking at it, I was thinking "OK, where in this thought process will the US Army screw this up beyond recovery?"

Possibilities;
  • try to stuff an intermediate-power cartridge into a 2.26" COAL so that it will run, unreliably, in the AR and other platforms designed for 5.56x45
  • choose some finicky ball powder that pressure-spikes if the planets align badly
  • blow the shoulder forward to get more powder volume and velocity, and end up with a neck too short to grip bullets
  • non-standard rim diameter, making early wildcat testing impossible and thus leading to a shortfall of interior ballistics
  • failing to factor in long monometal bullets when setting COAL
  • inadequate case body taper, leading to sticky chambering and extraction
  • failure to include a basic AP load in initial testing
  • failure to consider SBRs and cans when testing powders
I'm sure there are a dozen more boo-boos available.

---------

Simon, you're falling into his trap! By shifting the "light" cartridge to a 6.5mm intermediate, he is setting up the introduction of a heavier, long range cartridge for MMGs & snipers. Lets say 7.62mm bullet diameter, about 3.5-3.6g of a reliable extruded powder, decent case taper, long neck, COAL that allows heavy VLD bullets, lets say about 63 or 64mm case length. :)

#15 Chris Werb

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Posted 03 September 2012 - 1101 AM

Tony, I believe the One Round mantra to be flawed. The reality is that yer individual has a finite distance in which he can deliver fire due primarily to training and visual considerations. It does vary but I would use 600m as an extreme limit for point fire. Beyond this, you need either equipment and skillsets that are beyond the infantryman like LR precision rifle training, tripods w. T&E etc.


Sorry Simon, but Tony addressed that argument in the article.

#16 Tony Williams

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Posted 03 September 2012 - 1121 AM

Tony, I believe the One Round mantra to be flawed.


Well, I don't expect everyone to agree with me! However, there's nothing very radical about the notion: most countries had it before WW2 and both the US and the UK (plus various other countries) wanted to get back to it afterwards. The 6.5mm Japanese Type 38 would have fitted the bill nicely, with a bit of updating (including a smaller case); the only reason the IJA went for a 7.7mm as well was because of the fashion for very long-range MG fire (2000+m); other examples of this introduced at around the same time being the 8mm Breda, the 8mm Swedish, 7.9mm Norwegian and 8mm Solothurn.

The reality is that yer individual has a finite distance in which he can deliver fire due primarily to training and visual considerations. It does vary but I would use 600m as an extreme limit for point fire. Beyond this, you need either equipment and skillsets that are beyond the infantryman like LR precision rifle training, tripods w. T&E etc.


I don't disagree with that, at least for the present. See my "response to objections #3": "For now, the long-range capability would primarily be of benefit in LMGs and sharpshooter rifles, but advanced sights currently in development include laser rangefinders and ballistic computers and can also take into account crosswinds and other variables. Although initially for snipers, it is not difficult to predict that they will become small and inexpensive enough to be available for infantry rifles within the foreseeable future. These will do for long-range rifle shooting what precision guidance kits have done for aircraft bombs, and will enable an average soldier to deliver accurate rifle fire to long range."

Ironically the Taliban responded the problem by developing their close and long teams, the former built around the 7.62x39 and RPG to manouevre, close and destroy the enemy, the latter with 7.62x54 as a base of fire. This in turn drove the NATO/ISAF responses.
This is a much more sensible and low risk approach IMO, to essentially have a 5.56NATO and a 7.62NATO replacement. Examples exist of both like 6.8SPC and the .338 Norma Mag on the LWMMG.


Again, we're not very far apart. I think that the .338 NM MG would be a great supplement to a GPC in the support role (maybe at company or platoon level) and long-range snipers could use the same ammo (somewhat better made...). My point is that by the time you get up the muzzle energy, size, weight and recoil of the 6.8mm Rem, you are in GPC territory - some adjustment to allow the use of bullets with a much better drag coefficient (the 6.8mm being squashed-up to fit into an AR-15) and you have a cartridge which can reach very effectively to 1000+m in the right weapon, saving the poor footsloggers from carrying anything heavier.

The One Round idea brings us back to 7.62NATO, too much bullet or not enough depending on what you are doing.


The 7.62 NATO was, and remains, a truly HORRIBLE botch of an attempt at a universal cartridge. I think that the decision makers in the US Army must have suffered a bout of collective insanity when they came up with that one. Who in their right minds could have believed that you could have a .30 cal cartridge which matched the .30-06 in range and hitting power yet could be fitted into a lightweight selective-fire rifle which could replace the M2 Carbine, M3 SMG and BAR as well as the Garand? As it was, the resulting M14 could only replace the Garand and it wasn't a huge step forward over that.

The .276 Pedersen would have been a vastly better choice for a universal cartridge, despite the excessively tapered case. With the case blown out and shortened a little, it would have been great (still would today). It even had a very finely-shaped bullet which provided much better long-range performance than most people think, yet when the .276 and .30-06 versions of the Garand were compared, the .276 generated only half of the free recoil energy.

#17 Tony Williams

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Posted 03 September 2012 - 1130 AM

All the time I was looking at it, I was thinking "OK, where in this thought process will the US Army screw this up beyond recovery?"



They might, but it depends on who they listen to. ARDEC did a through survey which came out in favour of a 6.35-6.8mm long-range rifle round. From what I've heard, the 6.5mm round which AMU have separately suggested for army rifles is spot-on; coincidentally, pretty much what I proposed in my article. A new standard rifle/MG cartridge only gets adopted once every couple of generations so I don't underestimate the difficulties, but I don't think it's impossible - merely very unlikely!

#18 Simon Tan

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Posted 03 September 2012 - 2220 PM

Chris...he addressed it to your satisfaction, not to mine.

How much 6.8SPC you have shot? I have shot it extensively and alongside 5.56 and 7.62 in semi-automatic and automatic. It is definitely more the former than the latter, especially in cyclic. It represents the upper limit of a controllability in a 7lb carbine type weapon at a 900rpm cyclic. The major encumbrance on the first gen post-556 intermediates is the AR15 magazine well. Eliminating that limitation allows the use of longer bullets without an excessive bottleneck. This is a game changer, along with the proper stacking of rounds vis the compromised stack previously used.

I really do not believe in issuing infantrymen with happy switches since pitifully few are trained to use them. It's bad enough in 5.56, a somewhat more powerful round will require significant recoil management. Can be done but it just adds to cost and complexity. However, an 'intermediate' 5.56 replacement is justified if thought through considering barrel lengths, weapon weight targets, cyclic rates, operating pressures and cartridge OAL.

If you ONLY consider it a 5.56x45/7.62x39 replacement, you;ll be OK. A 'universal' round is just going to flop.

#19 rmgill

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Posted 04 September 2012 - 1352 PM

Tony...this is so 2008. :P

Actually, I first worked this out in 1971 (http://www.quarry.ni...k/6.5mm GPC.jpg :P ) but it takes a while to convince the US Army of anything. However, we have the Ehrhart report in 2009, the ARDEC calibre study in 2011, the AMU report in 2012...they are gradually coming to See the LightTM!


Permission to post that link on Facebook of the image? That's cool gun geek stuff.

#20 JamesR

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Posted 04 September 2012 - 1835 PM

How much of a factor is barrel life?

The 223/556 and 308/762 Nato both have exceptional barrel life. All the 6mm and 6.5mm calibers I am familiar with have significantly less barrel life.

The 6.5 Creedmoor sounds pretty close to your Gpc concept but like the other 6.5 offerings its barrel life is limited when compared to the 308.




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