Banana vs straight magazine question

[offroaD]

I did some googling and I learned that banana shaped mags like the AK mags are curved because the round has a large taper on it so the mag needs to be curved for reliable feeding. That makes sense, but the next question that I couldnt find an answer to is why design your ammo to be tapered? Is there an advantage? I was thinking that the taper design might allow for more room for gun powder, and although I've never seen an AK round open my general understanding is that most rounds dont fully maximize the space in the cartridge and the extra space a tapered design might offer is minimal. So does anyone have a legitimate answer?

 

[clandestine]

Straight Walled Casings are harder to extract on a semi auto. Tapered casings by design wont grab as much.

 

[offroaD]

Straight Walled Casings are harder to extract on a semi auto. Tapered casings by design wont grab as much.

so out of curiosity why did the AR platform go with a straight case? I know it's ever so slightly tapered, but it seems like a lot of people consider it to be straight. Or is that small taper that the 556 has enough to take advantage of this principal?

 

[amoebicmagician]

Straight Walled Casings are harder to extract on a semi auto. Tapered casings by design wont grab as much.

yeppers, also bottlenecked/tapered cartridges feed easier into a chamber. Have you seen an AK 'feed ramp'?

It's basically just a rectangle of steel, ever so slightly leading to the gaping maw of the chamber, you would be amazed how reliably those bottle necked cartridges find their way in there though.

Long story short, it is a shape optimized to feed and extract reliably when fired from box magazines as opposed to cloth belts or disintegrating links like the 7.62x54r with it's monstrous rim that makes stacking them in a box mag a COMPLETE nightmare.

 

[amoebicmagician]

so out of curiosity why did the AR platform go with a straight case? I know it's ever so slightly tapered, but it seems like a lot of people consider it to be straight. Or is that small taper that the 556 has enough to take advantage of this principal?

it is enough to make a difference, and frankly one of the big reasons was so we didn't need curvy ass magazines ungainly as all hell hanging off our gear and the necessity of machining a mag well to accomodate such a monstrosity

 

[Vile Shadow]

it is enough to make a difference, and frankly one of the big reasons was so we didn't need curvy ass magazines ungainly as all hell hanging off our gear and the necessity of machining a mag well to accomodate such a monstrosity

Yes. You all don't need those "high capacity banana clips".

 

[5.56blaster]

Yes. You all don't need those "high capacity banana clips".

And the folding thing that goes up for the flash thing. /

 

[shaddydan]

I want a banana hammock!

 

[outrider58]

I want a banana hammock!

Who doesn't!

 

[denimdan85]

I want a banana hammock!

Are you sure you don't mean plantain hammock?

 

[outrider58]

Are you sure you don't mean plantain hammock?

Which is bigger?

 

[Long1MD]

I can't remember the last time I heard the term "banana clip". I think it was before the 90's assault weapons ban.

 

[Vile Shadow]

I can't remember the last time I heard the term "banana clip". I think it was before the 90's assault weapons ban.

One of my co-workers says it.

And he was a Vietnam vet...

 

[friendlyhippo]

yeppers, also bottlenecked/tapered cartridges feed easier into a chamber. Have you seen an AK 'feed ramp'?

It's basically just a rectangle of steel, ever so slightly leading to the gaping maw of the chamber, you would be amazed how reliably those bottle necked cartridges find their way in there though.

Yup.

 

[CXD Arms]

When the AR-15 was designed, 20 round magazines were the norm, perhaps a carryover from the M-14 which didn't stay as the primary battle rifle for very long as it was?

Even with that, you can tell a lot about what the designer of a rifle is focusing on based on the characteristics of what was created. The AR-15 was designed to be a light "space aged plastic" rifle while the AK-47 was a more rugged 'throw in the mud' work in all conditions rifle. Tapered cartridges are more forgiving of dirt and fouling that a straight cartridge which........,

was part of the reason for early failures of the AR-15 when the powder was switched to a dirtier formula and thus the rifle became known as the 'Jam-O-Matic!'. Cases were actually welded/corroded in the chamber due to those factors adding up.


Tapered cartridges add to reliability but require a more curved magazine as the tradeoff

 

[Armadillofz1]

potato numba one, potato numba 2
NSFW language

 

[Pinecone]

was part of the reason for early failures of the AR-15 when the powder was switched to a dirtier formula and thus the rifle became known as the 'Jam-O-Matic!'. Cases were actually welded/corroded in the chamber due to those factors adding up.

Not exactly. The owder used had an excess of calcium carbonate (IIRC) after firing, and that got into the gas tube. Combined with moisture from the humidity, that would turn to cement in the gas tube, eventually clogging it if not cleaned soon enough.

NO gas, no extraction.

This also came a point where the users were told that due to the direct impingment design, the rifles did not need to be cleaned. And they were not issued cleaning kits.

So combination of the change in powder and the no cleaning, they had issues.

 

[JoeRinMD]

Rather than the case taper itself, I believe the bigger issue is the fact that the 7.62x39, like the 7.62x54R, .303 British and the .22 LR are all rimmed cartridge cases. Since the rims would interfere with each other in straight magazine, rimmed cartridges require a curved magazine for reliable feed with more than about 5-10 rounds in the mag.

This also came a point where the users were told that due to the direct impingment design, the rifles did not need to be cleaned. And they were not issued cleaning kits.

So combination of the change in powder and the no cleaning, they had issues.

I believe this was also due to McNamara's Office of the Secretary of Defense "whiz kids" getting into a bureaucratic tussle with the Army's Bureau of Ordance during the development/introduction of the M16. The Army had been resisting the M16 in every way possible, including changing the requirement from a 300yd range to a 500 yd kill capability. Since the cartridge case had already been chosen, and the rifle designed around it, to meet the shorter range, Armalite tried a different powder to get the additional range. This powder burned in the way mentioned above.

Then, the OSD Whiz Kids took at face value Armalite's marketing claim that the gun didn't need ANY cleaning. This was done over the protests of the Bureau of Ordnance that there wasn't a gun made which didn't need cleaning. The OSD perceived this as just another case of the Army's intransigence and bureaucratic resistance. However, in this case the Army was completely correct. And tragically, many soldiers died because of it.

JoeR

 

[outrider58]

When the AR-15 was designed, 20 round magazines were the norm, perhaps a carryover from the M-14 which didn't stay as the primary battle rifle for very long as it was?

Even with that, you can tell a lot about what the designer of a rifle is focusing on based on the characteristics of what was created. The AR-15 was designed to be a light "space aged plastic" rifle while the AK-47 was a more rugged 'throw in the mud' work in all conditions rifle. Tapered cartridges are more forgiving of dirt and fouling that a straight cartridge which........,

was part of the reason for early failures of the AR-15 when the powder was switched to a dirtier formula and thus the rifle became known as the 'Jam-O-Matic!'. Cases were actually welded/corroded in the chamber due to those factors adding up.


Tapered cartridges add to reliability but require a more curved magazine as the tradeoff

Not exactly. The owder used had an excess of calcium carbonate (IIRC) after firing, and that got into the gas tube. Combined with moisture from the humidity, that would turn to cement in the gas tube, eventually clogging it if not cleaned soon enough.

NO gas, no extraction.

This also came a point where the users were told that due to the direct impingment design, the rifles did not need to be cleaned. And they were not issued cleaning kits.

So combination of the change in powder and the no cleaning, they had issues.

Rather than the case taper itself, I believe the bigger issue is the fact that the 7.62x39, like the 7.62x54R, .303 British and the .22 LR are all rimmed cartridge cases. Since the rims would interfere with each other in straight magazine, rimmed cartridges require a curved magazine for reliable feed with more than about 5-10 rounds in the mag.



I believe this was also due to McNamara's Office of the Secretary of Defense "whiz kids" getting into a bureaucratic tussle with the Army's Bureau of Ordance during the development/introduction of the M16. The Army had been resisting the M16 in every way possible, including changing the requirement from a 300yd range to a 500 yd kill capability. Since the cartridge case had already been chosen, and the rifle designed around it, to meet the shorter range, Armalite tried a different powder to get the additional range. This powder burned in the way mentioned above.

Then, the OSD Whiz Kids took at face value Armalite's marketing claim that the gun didn't need ANY cleaning. This was done over the protests of the Bureau of Ordnance that there wasn't a gun made which didn't need cleaning. The OSD perceived this as just another case of the Army's intransigence and bureaucratic resistance. However, in this case the Army was completely correct. And tragically, many soldiers died because of it.

JoeR

Not to forget ABO's decision to forego chroming the chambers which added to M-16's failings.

 

[240 towles]

I want a banana hammock!