Why are magazines loaded from the bottom so common?

[barnbwt]

Actually, the BAR is every bit as good as the Bren gun

It wasn't until the FND that they were comparable. BAR didn't even have a pistol grip. I always found it odd that Browning made the thing gas operated, since the quasi-toggle lockup action would actually be particularly easy to operate via short recoil, and would honestly have been more typical of a design of that era. Rate of fire would probably be undesireably high for a that dumb "walking fire" doctrine, though (low ROF was ultimately very advantageous for its ultimate usage)

TCB

 

[lysanderxiii]

Recoil operated machine guns showed this to be largely a non-issue; I'm not aware of the Johnson rifle having any particular jam-affinity in excess of the Garand, even during its tenure in the Pacific. Jams, as always, are typically due to breech-area infiltration and binding (seems like most commonly when gunk finally gets shoved into the chamber alongside the case, which no action can really tolerate well)

The Johnson M1941 is not as accurate and a standard M1,m and they did not do as well as the M1 in the sand and mud tests. And, the Israeli Dror, just a Johnson LMG with a box magazine was horribly unreliable in the Middle-Eastern deserts. So much so that the Israelis gave-up the idea of indigenous production of LMGs to just buy Belgian MAG-58s. (and the one thing the Isrealis hate is relying on other people for weapons.)

With the Johnson, sand and dirt enter the barrel shroud via the cooling holes and and migrate forward and aft to the barrel bearings.

Fortunately, the barrel on a Johnson can be pulled in about 5 seconds (poke the nose of a round in a hole in the side of the stock) , cleaned and reassembled quickly.

Browning M2's pretty darned accurate, despite a moving barrel. As are MG42s, and most of these other designs. They lock up consistently, and just as with pistols, that's what matters. Especially since ammo variations combined with barrel harmonics likely outweigh the arc-length error introduced by a moving barrel bushing. If we still put 1000yd sight ladders on our infantry guns, you might have a point, though

In 1974, the Rock Island tested several machine guns for possible replacement for the troublesome M73/M219. During the technical performance phase of the testing, accuracy, accurate life, reliability, reliability under adverse conditions (mud, cold, hot, sand and dust), and performance in various attitudes (ie muzzle high, low, inverted, on its side, etc). Also, parts usage/breakage, ease of maintenance, etc.

Gun accuracy ranking:
C1A1
AAT-52
MAG-58
L8A1
PKM (using Soviet manufactured 7.62 x 54R ammunition)
M219 IP
M60E2
MG-3

You may gloat in the recoil operated C1 (basically an M37 modified to shoot 7.62 NATO out of M13 links) ranking first. However, reliability and reliability under adverse conditions it ranked last, with the less accurate MG-3, far surpassing it, along with all the other gas operated weapons.

Just as I stated, you can achieve accuracy by closing down the tolerances, but at the expense of reliability.

If a barrel has .005" clearance in its shroud/support, and the bearing length is 12 inches (about what an M1941 has) then the error of where the barrel points can be as great as 1.5 inches at 100 yards. That's on top of the usual factors that influence accuracy.

Yes, recoil operated weapons an be relatively accurate, take the Barrett .50s, but generally speaking, fixing the barrel in an unmoving manner to the receiver is better for accuracy.

Well it's not like the term "over-gassed" doesn't exist, either, and isn't the chief reason the AK has such famed reliability. This is a better criticism than the Army's that "the gun is unreliable with bayonet affixed" which could have been easily dealt with using a bayo design that functions as a muzzle booster. On a modern SBR-length gun with full-length free float tube, the barrel is just as shrouded as for a recoil operated gun, anyway, and a knife could be affixed onto that

An over-gassed rifle only has to deal with excessive bolt/bolt carrier velocity, in a recoil operated weapon, you have to deal with excessive bolt/bolt carrier velocity and excessive barrel velocity. And the barrel is a lot heavier, so you have more energy to dissipate.

The Johnson's magazine had a lot of fat & bulk that would be wholly unnecessary for a detachable-mag system. The M1 en-bloc system, despite it's complexity, was functionally quite similar to a short box magazine, and when upgraded to a BM59, really didn't change enormously.

The M1941 magazine is surprising light for its bulk, not much heavier than a 10-round M14 magazine....

And it has advantages over both the box magazine and the enbloc-clip. It can be topped off with a round in the chamber. It allows that a specialty cartridge can be inserted without opening the bolt or removing the magazine, useful if marking targets with a tracer, or firing a grenade.

(The BM-59 magazine arrangement is more like the M14 than anything. The only major differences between the BM-59 and the M14 are 1) the selector design is that of an M2 carbine, and 2) it retained the direct gas piston of the M1, instead of the gas cut-off piston. It also does not use a cam roller.)

Of course, there is also the fact that a certain measure of weight was required due to the cartridge selection. Gas guns have the advantage that they can play with gas ports rather than operating mass to tune the gun, and therefore can be lighter than recoil operation at certain power levels. I think if even 308 were used instead of 30-06, operating mass would be reduced significantly compared to something like an M1A which stayed about the same. Stepping down to 223 would be even more pronounced, though I honestly can't say if 5.56 NATO generates enough operating recoil to run such an action well at typical service barrel lengths --it really hasn't been tried that I'm aware of, the various delay-blowback systems being the primary alternative to gas operation (though they themselves are rather similar to short-recoil operation if you think about it)

The recoil energy developed by a 150 grain bullet with a muzzle velocity of 2800 fps is the same, no matter what cartridge it is fired from.

Note that all the formula are independent of cartridge...

The only gain is from the 3 grain decrease in charge weight, and that is negligible.

And no, delayed-blowback is not anything like a short recoil operation.

Absolutely agree. That said, we all know there are pistols that can and do fire a wide range of loads, so there are definitely design regions where one can bake enough extra margin into the system to handle a range of ammunition without impacting the shooting experience negatively --who's to say if those are in the "rifle area" of the design space, though? I honestly can't say, personally. I do know that 223 is too powerful for any theoretical recoil-operated handgun since the bolt velocity would be destructive, but perhaps an extra 10" of braked-barrel would tame that, leaving a system much more like an auto loading pistol as far as felt recoil and cycle speed.

Muzzle brakes are detrimental to regular rifle cartridge range recoil operation. A muzzle brake pulls the barrel forward, the exact opposite of what you need the barrel to do in recoil operation, especially in short recoil operation.

There is nothing inherently opposed to .223/5.56mm recoils operation. The barrel & bolt/bolt carrier weight would have to tailored to achieve the required energy to cycle the bolt, about 9.5 Joules. Which means the barrel-bolt combination would need to generate about 15 Joules to ensure that there was enough to cycle the bolt.

That would make for a heavy pistol.

I also happen to believe that either/both muzzle brakes and hydraulic buffer systems could be used to create a somewhat self-regulating recoil action, along the lines of how the M1A has its little gas cutoff feature to help protect that funky dogleg op-rod from being over driven.

TCB

As stated above, muzzle brakes are of limited value on recoil operated weapons, as they tend to retard barrel motion. Their use in pistols and other low powered cartridges is more to control flip, than the mitigate recoil.

At the other end of the spectrum, .50 caliber rifles have so much recoil something is required to keep the barrel from beating the recoiling parts the death, or having an 85 pound weapon to absorb the extra energy.

 

[lysanderxiii]

Except for the 10 round less capacity.

And the inability to sustain fire because the barrel can't be swapped.

And you can't mount a BAR on a tripod to use it as a support weapon.

But besides those things the BAR is almost as good as a Bren.



I've wondered if the doctrine came first or the Army developed the doctrine because of the weapons they got from Ordnance.

BSW

Both doctrine derived from WW1 experience.

EDIT: It should be noted that the French also felt the LMG should be a support weapon to the rifle in the assault, similar to the US, however, felt that in the defense, the role reversed. The Mle 1924 did not have a quick change barrel same as the M1918.

 

[lysanderxiii]

It wasn't until the FND that they were comparable. BAR didn't even have a pistol grip. I always found it odd that Browning made the thing gas operated, since the quasi-toggle lockup action would actually be particularly easy to operate via short recoil, and would honestly have been more typical of a design of that era. Rate of fire would probably be undesireably high for a that dumb "walking fire" doctrine, though (low ROF was ultimately very advantageous for its ultimate usage)

TCB

The High/Low rate selector was a much later development, 1938 to be exact. It was introduced in the M1918A2 along with the bipod. Both were specifically added to improve utility as a squad automatic rifle.

Oh, and the pistol grip and barrel change were originally part of the M1918A2 proposal, they were dropped from addition because the Army added a requirement that only retrofit modification would be considered. (budget constraints)

Other than those two changes the FN-D is pretty much the same as an M1918A2.

 

[Vern Humphrey]

The WW2 German TO&E of a rifle company had the mortar section op-conned to the rifle platoons at one per platoon. While this gave the platoon leader an awful lot of firepower, it also diluted the available indirect firepower of the company.

The Germans were not aware of the American Artillery Revolution -- in which keeping indirect fire weapons under one commander superceded farming them out in penny packets to maneuver units. When the Germans went up against US troops in North Africa the huger volume and effectiveness of American artillery convinced them the Americans had "automatic artillery."

Regarding my comments on the BAR versus the Bren:

Except for the 10 round less capacity.

And the inability to sustain fire because the barrel can't be swapped.

And you can't mount a BAR on a tripod to use it as a support weapon.

But besides those things the BAR is almost as good as a Bren.

While magazine capacity offers some advantage, in a weapon like the BAR or Bren it's only slight. The BAR compensated for a fixed barrel (and for reduced magazine capacity) with it's low cyclic rate. I used to keep mine in "low" and mostly tapped of single shots.

And if you have the M1919 machinegun -- which all Infantry platoons did -- that's the weapon you use on the tripod. The BAR has a different role.

 

[lysanderxiii]

The Germans were not aware of the American Artillery Revolution -- in which keeping indirect fire weapons under one commander superceded farming them out in penny packets to maneuver units. When the Germans went up against US troops in North Africa the huger volume and effectiveness of American artillery convinced them the Americans had "automatic artillery."

Regarding my comments on the BAR versus the Bren:



While magazine capacity offers some advantage, in a weapon like the BAR or Bren it's only slight. The BAR compensated for a fixed barrel (and for reduced magazine capacity) with it's low cyclic rate. I used to keep mine in "low" and mostly tapped of single shots.

And if you have the M1919 machinegun -- which all Infantry platoons did -- that's the weapon you use on the tripod. The BAR has a different role.

The German rifle company had available 12 MG34s or MG42s, one per squad. These could be used in both the light and medium MG role. He had 3 50mm mortars, also farmed out at one per platoon. The battalion also had a weapons company with 12 additional MG34/MG42s and six 81mm mortars.

The British used the same arrangement as the Germans, but with the heavy Vickers pushed back to division level into a MG battalion, each rifle battalion was op-conned one MG company (12 MGs), or employed as required by the Divisional CG. The battalion commander also owned six 3-inch mortars (actually, they measure 81 mm).

The US Army rifle company had 12 M1918s and 2 M1919s. The three 60mm mortars and the two M1919s belonged to the Company commander to employ as he saw fit. The battalion also had 8 M1917s (later M1917s or M1919s) in the heavy weapons company along with the six 81 mm mortars.

So you can see that the total number of weapons in a battalion is similar:

LMG - 36
M/HMG - 12 (US 14)
Lt Mortar - 9
Med Mortar - 6

But, who owns them and who gets to position them on the battlefield is quite different. Early in the war, the Germans even pushed the 81mm mortars down to one per platoon level (the company held in reserve got shorted). This allowed the individual platoon to have enormous offensive power, at the expense of firepower concentration. It should also be noted that the German 50mm mortar and the British 2-inch mortar are not nearly as capable of a indirect fire weapon as the US 60mm mortar.

There was a slight difference in the number of riflemen in a squad, the Germans and British had 10 man squads, the US, 13 men.

EDIT:
The USMC had 3 M1918s per squad, or 27 per company.
6 M1917s per rifle company (assigned to HQ section)
6 M1919s per rifle company (assigned - two to HQ section and two, two-gun MG squads in the weapons platoon)
3 60mm mortars (in the weapons platoon)
Battalion got an additional four 60mm mortars along with four 81mm mortars

So, the USMC were lighter by two in 81mm mortars but had a lot more 60mm mortars, BARs, and M/HMGs. Again the main difference being who owns what, and gets to position it on the battlefield.

Then there is the allocation of AT weapons, and .50 cal MGs.....

 

[Vern Humphrey]

But, who owns them and who gets to position them on the battlefield is quite different. Early in the war, the Germans even pushed the 81mm mortars down to one per platoon level (the company held in reserve got shorted). This allowed the individual platoon to have enormous offensive power, at the expense of firepower concentration. It should also be noted that the German 50mm mortar and the British 2-inch mortar are not nearly as capable of a indirect fire weapon as the US 60mm mortar.

That's exactly right. By centralizing control of mortars and artillery, the US Army multiplied their effect -- something our allies and enemies were unable to do.

For example at El Alamein, Montgomery had four miles of guns, hub to hub (imagine what a couple of German fighter-bombers could have done!) When the British or the Germans needed heavy fires, they had to mass guns. The Americans could mass fires with their guns dispersed.

 

[lysanderxiii]

double post

 

[lysanderxiii]

That's exactly right. By centralizing control of mortars and artillery, the US Army multiplied their effect -- something our allies and enemies were unable to do.

For example at El Alamein, Montgomery had four miles of guns, hub to hub (imagine what a couple of German fighter-bombers could have done!) When the British or the Germans needed heavy fires, they had to mass guns. The Americans could mass fires with their guns dispersed.

"Battery - three rounds", is a lot more effective than one tube shooting 18 rounds.

Part of it was also superior radio communication. US radios were generally more reliable than everyone else's. Without radio, the only way to call back corrections, or even call for fire, was through telephone lines.

In the highly mobile warfare that characterized Poland and France, the Germans did not have time to string wire all over the place.

It is also worthy of note that the Germans were still using the battery commander to adjust fire, as opposed to the US method of keeping the battery commander back at a fixed Fire Direction Center (FDC) at the battery, and using an expendable lieutenant as an FO.

 

[Sam1911]

Unless there's a side-mounted magazine for a mortar tube, I guess we've exhausted this one.