Joined: 7:48 PM - Apr 10, 2006

8:48 AM - Aug 10, 2018 #41

sergeante wrote:
A G Williams wrote:


The ballistic performance of the .280 was comparable to the .303 British, which seemed to do well enough in long-range MGs through two world wars.

Not too closely comparable, however. The .303 had about 20% more muzzle energy. That would make a difference at longer ranges. Which is why the .280 was acceptable in an assault rifle, but not a machine gun.
At long range, it isn't the muzzle energy that counts as much as the ballistic coefficient of the bullet. A well-shaped bullet will lose velocity and energy  more slowly, so will gradually catch up with and surpass a less well-shaped bullet in retained energy as the range extends. I don't offhand know the BCs of the bullets involved, but I do know their sectional densities (which determines the BC along with the form factor), as follows (the higher, the better):

.303 (174 grain, .311 diam) = 0.257 SD
.280 (140 grain, .284 diam) = 0.248 SD
7.62mm M80 ball (147 grain, .308 diam) = 0.221 SD

So, given equally good bullet shapes, the .280's BC would not be quite as good as the .303, but distinctly better than the 7.62mm NATO.

Incidentally, to match the SD of the .280, a 7.62mm would need a 165 grain bullet. 


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Joined: 12:24 AM - Nov 21, 2010

2:42 PM - Aug 10, 2018 #42

It's worth remembering that the Wehrmacht squad LMG, the MG42 on bipod, was roughly the same weight as the MAG/M240 (and effectively weighed more in ammo requirement). I'm not entirely sure what's wrong with a 10-12 kilo 7.62 belt fed in each squad/section.
The difference between "democracy" and "populism" is whether or not the ruling elite likes the outcome.
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Joined: 9:14 PM - Sep 27, 2011

4:26 PM - Aug 10, 2018 #43

A G Williams wrote:

At long range, it isn't the muzzle energy that counts as much as the ballistic coefficient of the bullet. A well-shaped bullet will lose velocity and energy  more slowly, so will gradually catch up with and surpass a less well-shaped bullet in retained energy as the range extends. I don't offhand know the BCs of the bullets involved, but I do know their sectional densities (which determines the BC along with the form factor), as follows (the higher, the better):

.303 (174 grain, .311 diam) = 0.257 SD
.280 (140 grain, .284 diam) = 0.248 SD
7.62mm M80 ball (147 grain, .308 diam) = 0.221 SD

So, given equally good bullet shapes, the .280's BC would not be quite as good as the .303, but distinctly better than the 7.62mm NATO.

Incidentally, to match the SD of the .280, a 7.62mm would need a 165 grain bullet. 
At any range, the muzzle energy you start out with effects the residual energy at point of impact. So, with similar ballistics (your claim, not mine), if you start out with 20% more energy, guess what? So much for .303 vs .280 as a long range MG round.

7.62x51mm is a different animal. Starts out with the same muzzle energy, in a lighter bullet. But that means going down range faster. I'm betting with that the M80 ball is ballistically superior to the Mk VIII ball. But that could be just me.
Up and forward on the starboard side, down and aft on the port. 

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Joined: 9:14 PM - Sep 27, 2011

4:32 PM - Aug 10, 2018 #44

IcelofAngeln wrote: It's worth remembering that the Wehrmacht squad LMG, the MG42 on bipod, was roughly the same weight as the MAG/M240 (and effectively weighed more in ammo requirement). I'm not entirely sure what's wrong with a 10-12 kilo 7.62 belt fed in each squad/section.
That Wehrmacht squad, when equipped with assault rifles, lost the LMG to a platoon MG squad. So MAG (or any kind of GPMG) at the squad level is a bit regressive.
Up and forward on the starboard side, down and aft on the port. 

The question of authority stalks the de-religionist project. (Paul Vander Klay)
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Joined: 11:33 PM - Jan 19, 2011

6:01 PM - Aug 10, 2018 #45

I note a GPMG appears to be a bit on the heavy side for room or trench clearing drills.  A 7.62 or 8mm cartridge is also rather long ranged for shooting automatic off a bipod.  That would seem to suggest a GPMG really needs a training and elevation unit to get the most out of it.  This all leads to the idea that a GPMG might make an adequate but less than ideal substitute for a light weight LMG or automatic rifle at the squad level.  On the other hand, that might well make it ideally placed as a platoon level asset, in a machine gun squad.
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Joined: 9:14 PM - Sep 27, 2011

8:11 PM - Aug 10, 2018 #46

Cody2 wrote: I note a GPMG appears to be a bit on the heavy side for room or trench clearing drills.  A 7.62 or 8mm cartridge is also rather long ranged for shooting automatic off a bipod.  That would seem to suggest a GPMG really needs a training and elevation unit to get the most out of it.  This all leads to the idea that a GPMG might make an adequate but less than ideal substitute for a light weight LMG or automatic rifle at the squad level.  On the other hand, that might well make it ideally placed as a platoon level asset, in a machine gun squad.
Well, I'm thinking the Germans left the machine guns outside for local security, and took the rest of each squad inside the building or trench. Which would be doctrinal for machine gun employment anyway -- you always want to keep them as close to ground level as possible, with the deepest (not necedsarily broadest) fields of fire. Also, that way you don't waste the power of the full-power cartridge.

WRT GPMG as a technical category, it's intended to be a crossover artist.

It's light enough to be carried by a small team and used on the bipod. The use cases for this are patrol and closely accompanying the attack.

It's also robust enough to be used at the platoon and company level, fired from the tripod, over the course of a deliberate engagement. The use cases for this are the traditional ones of static defense, and supporting an attack.

And, not really a role any more, but included for completeness, at the battalion level, with plenty of ammo and spare barrels, the GPMG was a support fire utility on both the offense and defense.
Up and forward on the starboard side, down and aft on the port. 

The question of authority stalks the de-religionist project. (Paul Vander Klay)
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Joined: 7:48 PM - Apr 10, 2006

1:32 PM - Aug 11, 2018 #47

sergeante wrote:
A G Williams wrote:

At long range, it isn't the muzzle energy that counts as much as the ballistic coefficient of the bullet. A well-shaped bullet will lose velocity and energy  more slowly, so will gradually catch up with and surpass a less well-shaped bullet in retained energy as the range extends. I don't offhand know the BCs of the bullets involved, but I do know their sectional densities (which determines the BC along with the form factor), as follows (the higher, the better):

.303 (174 grain, .311 diam) = 0.257 SD
.280 (140 grain, .284 diam) = 0.248 SD
7.62mm M80 ball (147 grain, .308 diam) = 0.221 SD

So, given equally good bullet shapes, the .280's BC would not be quite as good as the .303, but distinctly better than the 7.62mm NATO.

Incidentally, to match the SD of the .280, a 7.62mm would need a 165 grain bullet. 
At any range, the muzzle energy you start out with effects the residual energy at point of impact. So, with similar ballistics (your claim, not mine), if you start out with 20% more energy, guess what? So much for .303 vs .280 as a long range MG round.

7.62x51mm is a different animal. Starts out with the same muzzle energy, in a lighter bullet. But that means going down range faster. I'm betting with that the M80 ball is ballistically superior to the Mk VIII ball. But that could be just me.
A bit of digging produced BCs for the M80 of .200 and the .280/30 140 grain as about .220. The .303 Mk VII ought to be slightly better than the .280/30, the .303 Mk VIII noticeably better. 

Of course, the concept of "long range MG fire" has changed somewhat over time. In the days of the Vickers it was around 2,000-3,000 yards (the Mk VIII took that beyond 4,000 yards); at the time of the 1950 NATO trials they were looking at 2,000 yards maximum; nowadays it would be less than that. Anyway, the .280/30 was designed to be effective out to 2,000 yards, which was enough for a GPMG.

Practically speaking, the M80 had better ballistics for shooting out towards 1,000 yards because the flatter trajectory and shorter flight time improved the hit probability. That was about the practical limit though (US snipers used a 175 grain bullet, which is better for long range, but obviously the MV went down).


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Joined: 5:38 AM - May 05, 2006

6:05 AM - Aug 12, 2018 #48

ChrisPat wrote:
sergeante wrote: Long way around the barn analysis. I read a TFB article, quoting a British Army source, that mentions the suppression range as 1384m. That oddly specific value turns out to be the Charge 2 maximum range. With available charges numbered 0 to 5, I'm guessing that's the maximum handheld charge. Conclusion: they're using the weapon in the handheld mode as routine.
Could be.  In which case the Pl as a level where weapons are applied and the Coy as not has won out over the Coy having its own fire effect capability.  Note I don't say either is right or wrong, just that the former is what Brit Inf are used to.

Additionally the context of this weapon is always the dismounted platoon. So figure a platoon weapon.
Yarp, same detail.  Most times you throw new kit at folks they'll do with it what they're used too, no matter what you thought you were enabling them to do.

Problem is, the weapon and ammunition taken together are too heavy for day-to-day carry at the rifle platoon level. At the same time, the 60mm mortar has been recognized since WW2 as an effective and efficient weapon at the compamy level.
Yarp to Pl level load / effect.  Hence 51mm.  60mm as a Coy weapon, yarp but only by those whose mindset includes Coy level fire support.  That's not Brit Inf; quite possibly should be but isn't.

I think my question is, are GPMG teams, in the current or looking-forward organization,  permanent, first class citizens at the platoon or company level, or are they temporary entities created by giving a rifle fire team a gun and some belts of ammo?

Not quite either; a GPMG (SF) will be attached to a tactical commander.  It'll come ready to work so not  just a gun plus ammo but at the same time it won't be a pernanent part of the element it joins.  Long term they are, or should be, part of Support Coy which is a Coy in its own right.  Significantly Sp Coy OC out ranks rifle Coy OCs.  This ensures (should do) that the specialists get to do their specialist training instead of making up numbers in the rifle Pls.
I don't know about other folks, but when I see a big glob of text with replies merged in with the original, I just skip the post and move on ....
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Joined: 7:51 AM - Jun 18, 2015

8:55 AM - Aug 12, 2018 #49

Steve Crandell wrote: I don't know about other folks, but when I see a big glob of text with replies merged in with the original, I just skip the post and move on ....
Yep, me too.
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Joined: 2:52 PM - Aug 30, 2005

9:24 AM - Aug 12, 2018 #50

Steve Crandell wrote:
I don't know about other folks, but when I see a big glob of text with replies merged in with the original, I just skip the post and move on ....
That's sad. You have some informed people offering their opinions and you can't be bothered to read? I guess it's more a reflection on just not being interested in the subject. 
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