So as an overreach replacement for .50, how about a long recoil 20mm? Which one? x82, x102 or x128?

gatnerd said:

The BREN gun is the ultimate confusing one. It straddles the line across all categories...

The BREN is mag-fed, so I always thought it fit in the automatic rifle category, while a lot of other folks argue that it's a mag-fed LMG.

It clearly was widely used as a squad automatic weapon, but GPMG?  Was the BREN ever used as a coax machine gun in tanks or IFVs?

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An exception to the "fired from a bipod = LMG" rule is the tripod-mounted M1919A4 Browning, which the US Army considered an LMG.

stancrist said:

I don't know of anyone else who defines SAW = SCHV LMG.

I think the definition is really obvious. The weapon widely known and mostly assosiated with the term SAW is the M249. Which is a SCHV weapon. The difference between the M249 and other LMGs really is the caliber. Later the term was used for other weapons filling a similar role. Using SAW for full caliber belt feds came much later. Its actually pretty recent.
This is at least my perception of the last decades.

I just picked up the term SAW and used it to describe SCHV LMGs because the former is shorter, I am lazy and to me it was an obvious thing. There also was a need to distingish the two because people in a SCHV vs full power or 5,56 vs 7,62 debate people would commonly refer to 5,56 belt feds as LMGs but they are simply not the same category of weapon as full caliber MGs. The capability gap is to big.

stancrist said:

The US Army considers the M240 to be a MMG, regardless of what type mount is used.

Ok, but this clearly is a US special and a nomenclature choice based on something not technical at all. The M240 being a variant of the MG is a GPMG.
Coming back to the being lazy thing how is distingished between the different uses? MMG on bipod and MMG on mount? Without further information just mentioning MMG would be useless because it could be anything.

gatnerd said:

dont imagine many will go for buying more from Turkey, even if they are a NATO member with solid arms industry.

Actually it was tried. Not only from Turkey but from Pakistan as well. It was found out that the parts are not up to spec. They don't meet the German standards. Reworking them was so expensive and time consuming that small scale production on demand in Germany was effectively cheaper. So the idea was shelved.

graylion said:

So as an overreach replacement for .50, how about a long recoil 20mm? Which one? x82, x102 or x128?

In what role? What is the intended target? Who is to use it? What .50 loading? Mobility?

Just saying it should have a longer effective range than .50 is not really helpfull. Depending on loading and bullet the .338 Lapua can reach longer effective ranges than common .50 loads. There have been other long range cartidges specifially designed to overreach .50. No need to go bigger.

schnuersi said:

graylion said: So as an overreach replacement for .50, how about a long recoil 20mm? Which one? x82, x102 or x128? In what role? What is the intended target? Who is to use it? What .50 loading? Mobility? Just saying it should have a longer effective range than .50 is not really helpfull. Depending on loading and bullet the .338 Lapua can reach longer effective ranges than common .50 loads. There have been other long range cartidges specifially designed to overreach .50. No need to go bigger.

As a more destructive successor in the same role, also with more range utilising the aiming capabilities of RWS. 

graylion said:

As a more destructive successor in the same role

That is still pretty soft since the .50 is used in several roles.

Since its supposed to be more destructive I assume its for anti vehicle work. Basically any 20 mm outperforms the .50 cal in this regard. The question is what is the desired target spectrum and required range.
The 20 x 139 APDS used by the German Army can effectively engage an BMP over the frontal arc behond 1000 m. It penetrates ~50 mm RHA at this distance. If you want to engage Soviet era vintage AFVs in the 1000-2000 m range band this is the smalles gun that delivers this capability.

graylion said:

also with more range utilising the aiming capabilities of RWS.

Again any 20 mm will do.

nincomp said:

Do you see any advantage to higher-pressure variants of these cartridges?  Not necessarily 80,000psi, but more than the 52,000 psi used by the ARC to protect an AR15's bolt.  BTW, Hornady publishes "bolt gun" loads at 62,000psi for the 6mm ARC, but it is difficult to gage the performance increase vs the "gas gun" loads since since they used a 24" (610mm) barrel for "bolt" data and 18" (457mm) for the "gas gun".

Well, if you increase the pressure, you can also reduce the case diameter.

Compacted loads, as used for LSAT spiral 3 for example, or even aggregated loads used for caseless rounds, are also an interesting path to follow. As a sidenote, the "reduced volume" claimed by Textron for their telescoped rounds (versus conventional rounds) was a direct consequence of the use of compacted powder loads.

The FAMAS MSD powder load was 2.4 g and the cartridge volume was smaller than the 5.56 x 45 mm case. Using an aggregated load of common NC powder allows a loading density of ~1.5 g/cm^3 (instead of <1 g/cm^3), so suddenly you can put your typical .22 Nosler charge into a .222 Rem case.

When you write about "compacted powder loads", are they make with common powders literally pressed tighter in the case, or are they something else?

FWIW, it seems that Hornady compacts regular powders more than most to make its SuperPerformance ammunition.  I read in the 6.8 SPC forum that some "standard"  Hornady factory ammo is compacted so much that the cases bulge slightly.  One barrel maker recently noted that his chamber reamers  have been modified to make extraction of these rounds more reliable.

schnuersi said:

The 20 x 139 APDS used by the German Army can effectively engage an BMP over the frontal arc behond 1000 m. It penetrates ~50 mm RHA at this distance. If you want to engage Soviet era vintage AFVs in the 1000-2000 m range band this is the smalles gun that delivers this capability.

I was thinking defeating STANAG 4