Military Guns and Ammunition

Hosted by autogun

This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons.

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Exploring The Design Space   Ammunition <20mm

Started 25/7/15 by NathanielF; 126367 views.

From: tidusyuki


Thanks for the links. After looking at those patent images for quite sometime unfortunately i still don't really understand the barrel mating procedure nor how the barrel is supposed to be placed tightly inside the upper. The detailed description has so many engineering terms that are quite hard to grasp either. Mind explaining it to me?

Also I'm just really curious about it. How is the barrel block/trunnion manufactured and attached in the extruded upper?
here in the MCX barrel block there's no visible screws nor pin unlike on those SCAR type rifles.


Msg 6327.1146 deleted

From: QuintusO


So the most recent versions of 5.56 Supercruise (which is getting renamed soon for confusion reasons) is outperforming 6.8mm GP for raw energy at 1KM.


From: QuintusO


Supercruise continues to do well:

  • Edited 26 September 2020 18:45  by  QuintusO

From: QuintusO


Many projects have come and gone since the last time I posted here.

Figured there might be some interest in the current effort. M4 retrofit for 6.5 Grendel w/ composite case, including new bolt, barrel, barrel extension, carrier, and magazine.

Recently got done with some FEA on the new bolt design, strength vs the standard 6.5 Grendel bolt is improved by 17%. This allows a higher operating pressure of 75,000 PSI within an AR-15 format. That, combined with the Mk3 VKO design (which recently underwent their first real life flight test), gives us a muzzle velocity of 2,770 ft/s from a 14.5" barrel with a 100gr bullet G7 BC 0.284. This approaches the ballistics of the 6.5 Creedmoor, but does so from the existing small frame format. Round weight is comparable to M855.

Additional improvements to the carrier allow for dramatically improved upper receiver life, Cam pin drag is eliminated, and operating margin greatly improved.

I'm just one guy, so chances are high this project goes nowhere, but I know it's the kind of thing that gets attention around here so I figured I'd mention it.


From: autogun


In new money, that's 6.48 g at 844 m/s, for 2,308 J ME with moderate recoil (but presumably a good suppressor required!).

That would appear to be light enough (in weight and recoil) to replace the 5.56 mm, while having the long-range performance to make 7.62x51 class weapons unnecessary at squad level. Sounds promising for a GPC...

PS how close can you get to that BC with an EPR-construction bullet?

  • Edited 02 January 2021 4:55  by  autogun

From: smg762


For GPC I thought about a single rifle chambered for a 762 'equivalent' round,  but far more weight efficient.  Let's say 6. 5mm polymer case. 

The rifle can caliber convert to a much smaller round,  e.g.  a 204 vartarg type of round.  This means that most times you can deploy the small round.  If fighting moves to the mountains you can switch to the 6. 5


From: Farmplinker


Have you tried a 120-grain bullet yet? Seems like that might be wanted for a long-range loading. But like autogun says, it looks promising. Good luck with the system!


From: QuintusO


We just got done with the FEA on a new bolt iteration (newer than the last one) which should bring the MAP up to 80,000 PSI, which is right about the limit for composite cases anyway. Performance up from 2,770 ft/s to 2,830 ft/s. We're still using Carpenter 158 lol.

autogun said:

PS how close can you get to that BC with an EPR-construction bullet?

Depending on design, identical. I have some schemes for that.

  • Edited 02 January 2021 15:45  by  QuintusO