Military Guns and Ammunition

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This is intended for people interested in the subject of military guns and their ammunition, with emphasis on automatic weapons, particularly in larger calibres (12.7+mm).

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Exploring The Design Space   Ammunition <20mm

Started 25/7/15 by NathanielF; 77217 views.

From: SCHVPapist


At the prompting of some friends, I recently read through another sterling DTIC work on the topic of suppression, "The Identification of Objective Relationships Between Small Arms Fire Characteristics and Effectiveness of Suppressive Fire" which can be located at There are a few takeaways that may be of interest to the small arms designer. Namely "Grotesque terminal effects of small arms projectiles, when coupled with unique auditory signatures, are recommended as a source of increased fear and suppression." This is evidenced in the text by an interview with an individual who had seen "a considerable amount of combat."

A: "The AK, I think, you know, the men are scared of AK. The AK has got a lot bigger round than the 16 does, and it will make a bigger hole in you. But I trust the 16 myself."
Q: "Why the 16 more than the AK?"
A: "First of all, the 16 is a lot faster. And the bullet twists and turns. It's been known to anyway, and if it does hit you, it won't just go through one spot, it'll travel down your bone, or, it won't, you know... ."
Q: "And an AK won't do that?
A: "It just goes right through you." "


Q: "Forgetting about the M16, 'cause it's an American-made weapon, what do you think, other than that, what do you think I of their small arms?"
A: "Well, [51 Caliber machine gun], but I've never run into a 51. I've got to I take into consideration what they have, and they don't have 51s down here 'cause they can't move them."
Q: "Why do you think the 51 is so bad?"
A: "Well, like getting hit by an AK, getting hit by a 16 is worse than an AK, but getting hit by those 51s, you got a lot more power and they can't run with them. With an AK they can run, and they will run. But with a 51 they'll'Just sit there and fire away." 

Obviously there will always be restrictions - whether driven by legal concerns or performance constraints - that reduce the maximum soft tissue lethality of rounds. However, the physical wounding capability of a weapon does appear to have direct influence of its ability to suppress experienced combatants.

Msg 6327.1002 deleted

From: gatnerd


"However, the physical wounding capability of a weapon does appear to have direct influence of its ability to suppress experienced combatants."

That makes total sense; 22lr has poor suppressive characteristics, yet (extreme example) if .22lr's were coated in neurotoxin, where even a scratch produces a dramatically awful demise, they would be extremely suppressive after the first few encounters. 


From: QuintusO


Here's a graph I made to illustrate why 30 round magazines are so popular:

  • Edited 06 June 2020 16:02  by  QuintusO

From: EmericD


QuintusO said...

Here's a graph I made to illustrate why 30 round magazines are so popular:

Interesting... so what's the difference between 20, 25 & 30?


From: QuintusO


It is true that the uptime difference between 20 and 30 round capacities is not that high, but I'd still rather have 30 than 20, as long as it was reasonably feasible. The point difference between 20 and 30 is the same as 30 and 50, just to give you an idea. Can you roll with 20s? Yes, many have. Is it better to have 30s? I think so, if not for pure uptime reasons. 


From: taschoene


Is "uptime" really a critical measure for an individual combat rifle though?  Riflemen should not be in the business of just dumping rounds downrange as fast as possible.  That's what belt-fed machine guns are for, if it's needed at all. The rifle's main job is aimed fire and riflemen should be taking time between shots/bursts to aim, observe, move, etc. Rifles used for prolonged rapid fire will heat up so quickly that they become effectively worthless long before the impact of "uptime" becomes relevant on the battlefield.  

I suspect that magazine height is actually a more important driver of capacity.  That governs how low the gunner can get with a loaded rifle, which is what an infantry soldier I  combat often cares about most. It also explains why we settled on 20-round 7.62 mags and 30-round 5.56 mags; they're about the same height, and about right to aim from prone without digging the magazine into the ground.  


From: QuintusO


Did you notice that the top curve assumes a sedate rate of fire of 45 rds/min? Uptime is a measure of the percentage of the time your gun is up and ready to shoot, as opposed to reloading.

Mag height is the theory everyone's kicked about for years, but it doesn't explain why, for example, drum mags aren't popular among AK users. Reliable, efficient drums have existed for decades, but are rarely seen.

If the height theory is the case, why aren't AK mags 25 rounds? Why are RPK mags 40 rounds? 

In fact, shooting prone, I've never had any problem with my AK-74. It's a different posture than a bolt action for sure, but it works fine. AK mags are very, very long, about as long as 40 round AR mags. Yet we don't see 40 round AR mags very often. On the flip side, many drums are no longer than their double stack counterparts, so that doesn't explain the paucity of their use.

In fact, it's only off the *bench* that I find mag height to be a big issue, and then *30* rounders are too tall, which is why I almost always use 20s in that situation. I suspect this is where that idea comes from.

Not to mention, prone shooting is not the primary method of shooting anymore. So you'd expect a return to larger magazine sizes. We're not seeing as much of that as I'd expect.

The thing is, the uptime curve does not show reasons NOT to carry large mags. All it shows is that there are diminishing returns past a certain point, given an average rate of fire. And that helps explain why, despite fairly modest penalties, we don't really see a lot of use of higher cap mags, even though they exist!

  • Edited 07 June 2020 22:45  by  QuintusO

From: EmericD


Thank you.

So the biggest jump was going from 5/8 rounds to 20, above 20 it looks more like "nice to have" than "combat effectiveness will suffer" kind of requirement.