Military round comparisons

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Sorry to take so long to reply to previous posts.

LRRP52, according to live fire test results I have seen using 6.5 mm Grendel rounds fired from an AR15 platform, barrel length reductions DO have a significant effect on muzzle energy and retained energy at range. There is also a significant difference between direct gas impingement designs and AR15 clones with piston operated systems. This wouldn't be the first time that data calculated using a ballistics programme differed from real world testing. I think the best thing to do is to agree to disagree with your data.

Can you share the results you are referring to? We try to stick to real numbers here as much as possible. We can't discuss things of which we know not. I'd be interested in seeing exactly what you are referring to.

Secondly, once a military spec ball round is developed, rather than an open tip match ammunition, you would also expect to see an performance degradation. Creating a finely tuned target round that performs well on a range is, as I am sure you will agree, a very different proposition from creating a military spec round designed to deliver consistent results across a variety of combat theatres, with varying operating temperatures, at all battle ranges, across all engagement types and against human targets with and without body armour.

So, while the 6.5 Grendel is pretty darn good, it isn't quite the match for 7.62 mm that it needs to be, once you refine it for military use. This is something that at least three military weapon manufacturers have been looking at over the last 12 months, plus the US Army Marksmanship Unit.

My contention is that any true modern GPC cartridge must be a match for 7.62 mm in terms of range and terminal effectiveness from 0 to 1,200 metres. Without meeting this requirement, we will be overmatched by an enemy using 7.62 mm x 54R as well as 7.62 mm NATO.

The current Grendel case is filled to capacity, so the only way to put more energy behind the projectile is to lengthen it. As soon as you do this, you need a longer action length than that of the AR15 platform. So the ideal platform will either add length to an existing AR15 design or to lighten an AR10 action. In either case, you end up with a weapon that weighs in between an AR15 and and AR10. Give me 12 months and I'll tell you which option works better. The extra weapon weight also offsets the increase in recoil versus 5.56 mm.

The 7 mm UIAC is a very interesting design, but it is so close to existing 7.62 mm NATO in size and weight, why would you bother changing? Too much cost for too little benefit. My view that a GPC cartridge is only viable if it delivers 7.62 mm performance in a lighter package.

Is it possible to create a lengthened 6.5 mm Grendel that delivers superb performance in a package that still weighs around 18 grams? I believe it is.

For a long time, people viewed the ideal military cartridge as having a performance in between 5.56 mm and 7.62 mm. That view is now wrong. The 6.25 mm British and 6 mm US SAW cartridges were very close to matching 7.62 mm in a lighter package. With improved propellants and bullet design, we can achieve the same goal, albeit with a slightly larger calibre to deliver the necessary projectile weight in a lead free bullet.

"We" being whom? Just curious in the interest of disclosure. Are you a solo tinkerer, a manufacturer, a rep for a manufacturer, mad scientist, etc....?

As for your comments on velocities and barrel lengths--- We don't need calculators for real world velocities. We already have our own barrels of various lengths, and chronographs to boot. What lengths are you specifically questioning, and with what ammo?

I already have 10.5", 14.5", and 19.5" barrels myself. What ammo are you questioning data on? AA factory 123 Scenar loads? Wolf 120 MPT loads? Hornady 123 Amax loads?

If we seem itchy, it's because we've owned and been shooting these cartridges ourselves for years, and when someone new pops up and tells us we don't know jack, well.... Show me, please. I'm always open to correction if i'm factually wrong on something. Velocities are facts, not opinions. Perhaps I've misunderstood something somewhere?

Would you like velocity data for 10.5", 14.5", and 19.5" barrels? I can chrono mine if you happen to pick something I own ammo wise.

It could just be me, but I kind of get the impression you may be splitting hairs here intentionally-- with some possible ulterior point to prove? Do you perhaps have something to market, and are setting up your case for it before presenting it? I'm just being sure I understand your motives completely.