Why did they continue to rely on firearms?

[Cmdr. Setsuna F. Seyei]

There is nothing special about either the accuracy of the 5.56mm NATO or the "stopping/penetrating power" of the 7.62x39mm. Accuracy is far more dependent upon the gun than the cartridge. The 7.62x39mm is a little less powerful than the classic .30-30 Winchester, which is considered marginal for deer-sized game. It is far less powerful than a 7.62mm NATO / .308 Winchester or .30-06 Springfield.

The FN 5.7x28mm which the P90 is chambered for is significantly less powerful than the 5.56mm NATO / .223 Remington. It is similar in power to a .22 Hornet. The 5.56mm NATO is considered underpowered for deer-sized game by responsible hunters, and the .22 Hornet even more so. They are both considered "varmint" cartridges (e.g. groundhogs), and the .22 Hornet a short-range one at that. The 5.56mm NATO is considered a medium-range varmint cartridge, and cartridges such as the .220 Swift and .22-250 Remington are considered long-range varmint cartridges.

In any event, while the 5.7x28mm can generally defeat typical soft body armor out to a certain distance (as can any other similar cartridge), that is current Earth-technology body armor. We don't have here on Earth, for example, "Trinium", which is "an element that is a hundred times lighter and stronger than steel when refined".



No, a .22 Hornet-class cartridge can not even come close to penetrating 2 feet of solid steel. A .50 BMG, which makes a 5.7x28mm look like a cap gun (Here's a comparison picture; the 4.6×30mm cartridge in the #3 position is similar in dimensions to the P90's 5.7x28mm cartridge), can only get through about 1 inch of steel armor plate, though it might make it through 2 inches of mild steel. Here's a video showing a 5.7x28mm armor-piercing round failing to penetrate a steel plate which is approximately 1/4 inch thick.

Also, of course the Goa'uld are concerned with keeping their Jaffa alive. Their Jaffa are their primary source of power, and their last line of defense. They may be callous toward a Jaffa here and there when they have plenty at their disposal, but they certainly don't want their enemies winning battles against them.



This claim is as incredible as the 2-feet of steel penetration claim. They use full-auto nearly all the time. You can pick almost any episode at random and see them firing full-auto, and sustaining it for significantly more than 3 rounds at a time. I can provide evidence of this if need be; I'm just surprised that I'd need to.



Except, they do tons of small-team, on-the-ground missions, where "blasting them from space" isn't an option when they get in a tight spot.



For one thing, this shouldn't be a problem, as they have Star Trek style "replicator" technology. For another thing, they don't need to make very many of them. It is not as if they are equipping the entire U.S. Military with them; just a couple dozen 4-man teams.

first of all you are incorrect.
this is the data sheet directly pulled from the FN Herstal website

Just like the FN Five-seveN® MK2 handgun, the FN P90® submachine gun was developed around the 5.7x28mm ammunition to meet the Armies requirement in terms of efficiency.

Two versions are available:
FN P90® Standard
FN P90® Tactical

Either version can be fitted with an integrated visible or infrared laser.


Benefits

Stopping Power for Close Combat

The FN P90® submachine gun and the SS190 ball ammunition team up to defeat the enemy in all close combat situations.



High Accuracy

The high velocity of the 5.7x28mm ammunition guarantees a virtually flat trajectory up to 200m for outstanding accuracy.



Fully Reliable

The simple design of the mechanism, the unique feed mechanism and the materials used to manufacture the FN P90® make it highly reliable, whatever the conditions.



Rapid Deployment

The FN P90® is carried ready to fire. There is no need to extend any folding buttstock. Despite its shortness, the FN P90® is designed to be fired from the shoulder, giving maximum stability.



Quick Aiming

The FN P90® Standard is fitted with an integrated optical sight without magnification. The user can therefore shoot with both eyes open. Performance is fully retained in low light conditions thanks to a tritium capsule.



Easy to Carry

The compactness of the FN P90® allows easy movement in confined areas. The magazine is fully integrated in the upper part of the FN P90® for optimized ergonomics.



Fully Ambidextrous

The cocking handle and magazine catch can be operated from both sides of the FN P90®. The fire selector is under the trigger and can be operated in either hand. Empty cartridge cases are ejected downwards. The FN P90® can therefore be handled by right- and left-handed operators without any modification.



High Magazine Capacity

Since the 5.7x28mm rounds are light and small, the magazine fitted above the barrel can accept up to 50 cartridges.


Also the 5.7x28mm round has more stopping power than a 9mm round so comparing it to a .22 is ludacris.

[MaximRecoil]

first of all you are incorrect.
this is the data sheet directly pulled from the FN Herstal website

No, I am not incorrect, and absolutely nothing in the "data sheet directly pulled from the FN Herstal website" contradicts anything I said. For that matter, nothing in that data sheet even has anything to do with anything I said, which makes it a non sequitur. Given that you failed to even remotely establish that I am incorrect, your claim that I am incorrect is a baseless assertion, which can be dismissed out of hand.

Also the 5.7x28mm round has more stopping power than a 9mm round so comparing it to a .22 is ludacris.

Say what? ".22" refers to the diameter of the bullet, i.e., approximately .22". The 5.7x28mm has a bullet diameter of 5.7mm, which = .224", which means the 5.7x28mm is a ".22" itself.

Some ".22s" are far less powerful than the 5.7x28mm, such as the .22 Long Rifle. Some ".22s" are far more powerful, like the 5.56×45mm NATO / .223 Remington, or especially the .22-250 Remington and .220 Swift. Then there is a ".22" which has a similar level of power as the 5.7x28mm, i.e., the .22 Hornet, just as I said to begin with. The .22 Hornet actually has significantly more power than the 5.7x28mm, but it is the closest well-known centerfire ".22" that comes to mind.

The standard SS190 5.7x28mm round fires a 31 grain bullet at 2,350 ft/s, which = 394 ft·lbf of muzzle energy.

The .22 Hornet fires, for example, a 40 grain bullet at 2,826 ft/s, which = 710 ft·lbf of muzzle energy.

A closer comparison to the 5.7x28mm in terms of power is actually the tiny .22 Winchester Magnum Rimfire (AKA: ".22 Magnum"), which is essentially a "magnum" version of the .22 Long Rifle. It fires, for example, a 30 grain bullet at 2,300 ft/s, which = 322 ft·lbf of muzzle energy.

As for comparisons with the 9mm, the 5.7x28mm has a similar level of power to it in standard loads, and in some cases, the 9mm NATO has significantly more power than the 5.7x28mm (about 500 ft·lbf for +P+ 9mm NATO ammunition). However, due to the 5.7x28mm's small bullet diameter, it is better at penetrating soft body armor (as an analogy: a needle penetrates things easier than a hammer), and due to its higher velocity and bullet shape (i.e., better ballistic coefficient), it has a much flatter trajectory than a 9mm NATO.

There is nothing magical about a 5.7x28mm; anything it can do, an e.g. .22 Hornet can do better, because it has the same diameter bullet (it can actually use the same bullets, i.e., off-the-shelf .224" bullets can be handloaded into either one, or you could pull the bullet from a 5.7x28mm cartridge and handload it into a .22 Hornet cartridge) plus higher velocity. And anything a 5.7x28mm can do, the 5.56mm NATO can do way better, and the .22-250 or .220 Swift can do way, way better. Of course, none of them can come even remotely close to penetrating 2 feet of steel, which is the real "ludicrous" claim in this thread.

By the way, firearms are one of my areas of expertise (I've studied them for about 25 years), and no offense, but clearly the same can't be said for you. This creates a problem when it comes to a discussion/argument on the matter, because you need to understand the fundamentals before you can have a sensible discussion. Knowing the fundamentals prevents bizarreness such as claiming that a slightly-glorified .22 Magnum is able to penetrate 2 feet of steel (which is something that no shoulder-fired firearm cartridge can even come close to doing), or not understanding that the 5.7x28mm is itself a ".22", or that ".22" includes a wide variety of cartridges, from very low-powered (e.g. .22 Short: 29 grain bullet @ 830 ft/s for 44 t·lbf of muzzle energy, traditionally used in carnival shooting galleries) to relatively high-powered (e.g., .220 Swift: 40 grain bullet @ 4,213 ft/s for 1,577 ft·lbf of muzzle energy, commonly used for annihilating groundhogs and other varmints at 400 yards and beyond).