In my world I have one side armed with 'muskets' which utilize a simple form of magitek. Their 'bullet' is actually a magical 'blast' of condensed magic from the air. Despite being magical in theory, I am modeling them off of early muskets (at approximately the effectiveness of muskets present when Americas were being colonized by Europe). I intend for these magical rifles to be as close as possible to muskets in their combat effectiveness and logistics.
Some of the logistics of these magical rifles have been decided by the presence of other, rarer but stronger and closer range, magical guns. I want all magical guns to have the same rough feel when fired and I need the much rarer guns to function in a certain way, this affects how the rifles must function. However, I have plenty of room to adjust properties like range, accuracy, and reload time of rifles and am trying to adjust these to stay in keeping with the lethality of real muskets.
After these muskets are fired it takes some time for them to recharge before they have the power to fire again, roughly equivalent to the time it takes to reload old muskets. However, unlike real muskets that had to be manually loaded, these magical guns will recharge on their own without further action from the gunman.
When someone is struck with a blast from these magic-muskets, instead of suffering a gunshot wound they suffer an effect somewhere near that of a very localized blast of fire at the contact point and an electrical shock through the body. Generally I want these muskets to be roughly as fatal as real muskets when fired at normal military. Basically, I want how damage is done by a 'magic shot' to be ambiguous enough to leave room for things stronger than normal humans to easily survive getting hit once, but also believable be taken down by enough shots even if they are large enough that it seems they be able to mostly ignore the damage of a normal rifle.
I'm generally trying to stay close to the approximate effective range and accuracy of real muskets. However, the damage of a 'magic shot' has to function slightly differently. The rifles have a much longer range at which they can do damage, but once the shot passes a certain threshold the damage done by the shot will start to diminish rapidly (as the condensed energy blast starts to dissipate over time). Thus one can be shot from much farther, but at maximum range the shot will be only a minor pain, with shots only building up to lethal damage as one closes in to normal musket effective ranges, or possibly slightly shorter range. The idea is the overall effectiveness against charging soldiers should be the same as with normal muskets, with rare kills at larger range being counteracted by slightly lower effective ranges.
I expect the magical muskets, as I described them, will still be stronger than actual muskets I'm targeting. At minimum a non-gunman can presumably be trained to militia standard faster if they don't need to learn how to reload their gun, and the logistics of these guns is simplified since they can't run out of ammo.
I'm trying to figure out how much of an advantage these guns have over their real life counterparts, and what simple changes I may be able to make to keep them in line with their counterparts while keeping a similar feel to the weapon as described above.
I'm okay with it being easier to train militia with these guns, in fact I sort of want that. However, in combat would they have any obvious advantages or disadvantages? How much of an advantage is the fact that one doesn't have to be manually reloading while waiting for the gun to recharge between shots? Keep in mind the majority of users of these guns will be quickly trained militia or conscripts, only a few will be fully trained standing military.
Multiple people have already pointed out that muskets recharging on their own would allow one to constantly swap out guns to always have one ready to shoot. It's a good point, but I don't want it in my world. So I'm officially changing all guns such that they recharge much faster if (or don't recharge at all unless) a human is channeling magic into the gun, which requires only a minor mental focus and is easily learned. There is also a limit to rate that these guns can be mass produced, so it's best to have a gun in someone's hands so it's actively charging at all times.
A difference people haven't mentioned yet but which is huge - your magic musket can be reloaded lying down without any difficulty.
With ordinary muskets, most of the process is a lot easier standing up, because you use the benefit of gravity to drop in the powder and the shot, and besides you have to get yourself into the position where you can reach the muzzle of the gun. With your magic muskets, a shooter can quite happily lie on the ground and charge their gun without compromising on rate of fire.
This can change the battlefield a lot. Instead of having rows standing around, your musketteer would make much better use of battlefield cover, and be basically much harder to shoot. In a shooting duel a magic musket unit would thus easily outshoot normal muskets, forcing the other side to try and charge them in melee.
A couple of points I see here, that give magic muskets a major combat effectiveness edge over black powder muskets.
Range You mention a longer range. This means more shots can be delivered against an opposing force before it can close to melee range or even to counter-fire range. Meaning the enemy dies faster before your people begin to die (assuming they don't have your muskets, too). So this makes them more combat-effective than real-life muskets.
Weather Black powder Muzzle-loading weapons cannot be fired in rain. Period. Your weapons don't appear to face this restriction. Likewise, black powder must be stored very carefully to prevent moisture from ruining the powder. Point again to magic-muskets.
Ammo Your soldiers don't have to pack lead balls and powder. That's a tremendous advantage over powder. Their marching kit is lighter. They don't have to worry about dropping a powder horn in the fight or running out of shot. Their supply train doesn't have to include kegs of powder or blocks of lead and bullet molds. Campfires can't turn their supply wagon into a devastating bomb. Major points to magi-muskets.
Stance As mentioned by Fhnuzoag, your magimusket can be fired prone. Unlike a standard musket, which requires that you stand at least while reloading. Granted, if your musket forces (I hesitate to call them musketeers for obvious reasons) are based on standard European forces of the time, they will be used to working from a standing position and not used to fighting prone. I mean, how can you advance on an enemy line if your line is lying down on the job? But this is a huge difference. Your gunners can take up prone positions behind hills or in ditches, providing them cover. This is a radical departure from tactics of the era you're emulating.
..finally, a point that maybe works against magic is production cost and time.
Even if your magic weapons are literally just "take a musket and enchant it," your total production cost will be higher. Because you've got to pay your wizards in addition to your gunsmiths. I hope you're paying your wizards. Please pay your wizards. And that's if there are no material costs or complexities to your magic guns above and beyond standard guns. Plus however long the enchantment process takes.
Compare that to ammo. My father has a tool for making bullets for his muzzle loading rifles. The process was about as close to idiot proof as it gets. Get a fire. Heat lead in an iron pot. Pour lead into mold to make bullets. This is the sort of task soldiers could do on their own, if situations required it. Wizards aren't going to be quite as plentiful, I suspect, as people who can operate a simple die-cast tool. (Powder isn't so simple, of course.) But those costs are paid on a per-shot basis, sort of and are independent of the manufacturing costs that are due up front.
...and a couple of points that may be neutral depending on your weapons?
Armor It sounds like magic-muskets fire some sort of plasma-like effect. If so, how does that work against metal armor? One of the primary advantages of the black powder musket over archery was that steel armor was useless against the musket, but effective against arrows. Do your blasts penetrate armor as well as high velocity lead balls do?
Reliability How reliable are the magic weapons compared to real muskets? Do they misfire? Are they laser-accurate or pre-rifled-barrel gunpowder accurate? Do they require cleaning on a regular basis to maintain reliability and accuracy (even a few firings can foul the accuracy of a musket)? Are they subject to failure due to moisture, heat, cold, etc.? These kinds of questions may impact your "equations," as well.
Noise You haven't stated, but the noise level from a magi-musket could be none or a soft wooshing sound or some other extremely quiet level. This could have drastic impacts on warfare in several ways, if that's how it works. Imagine how much more effective snipers become if their weapons are silent? How different the battlefield will be if that field isn't inundated with the crash of musket-fire explosions?
Some argue that the noise of modern weapons contributes to PTSD. It definitely contributes to hearing loss. It also means your army's element of surprise lasts for exactly one volley of fire. Then everyone knows exactly where you fired from. Remove that sound and now you might get off several volleys of fire before the enemy can triangulate your position and return fire. The tactics of combat would be radically different, if this is the case.
Kick Muskets kick hard. But do magi-muskets kick like standard muskets? If not... You make it easier to keep your weapon trained on the enemy. You can fire longer before your shoulder looks like you've been kicked by a mule. You make it easier you build mobile weapon platforms (imagine scaling up to cannon that don't have to roll back and then be brought back onto target).
Weight If your magi-musket isn't quite as heavy, because it doesn't have use enough iron to contain the explosive force of black powder, then your weapon is now lighter, easier to carry. Marches aren't as tiring. Production costs might be slightly reduced, if less iron is needed (though that's offset by the cost to enchant, see above, Please pay your wizards).
Apart from all points already mentioned, the lack of powder smoke will be significant.
When volley firing muskets, smoke would cloud the immediate area, and hinder aimed fire. This was one of the reasons muskets were deployed en masse.
A smokeless musket will encourage aimed fire, and surprise tactis - a shooter's position will not immediately be given away by a black cloud.
The biggest impact by far will be on the logistic side, but smokeless guns certainly will (and have!) influence on tactical usage.
Even if you prevent the advantage of rifle swap between shots, that time is still a gift to the warrior over a muzzle loading rifle. They can maintain situational alertness and even reposition all while the recharging is taking place.
This is even more pronounced at short range. Attempting to load muzzle loader when under stress can easily double your reload time with shaking hands and loss of focus. There are several historical exhibits of blown breaches possibly due to the users loading multiple charges before firing. Alternatively, in the heat of battle not realizing "your" gun didn't fire. These issues would be solved by a magical gun that can't double load.
So to answer the question, YES a significant advantage that with even numbers would be insurmountable.
So your magic musket gives a few, obvious advantages. Less practice time devoted to loading since it's a mental skill rather than a physical one, no ammunition to carry, can be reloaded from any position, no huge cloud of smoke obscuring the target after the first shot...
At the same time, depending on how magic works in your system, you may have inadvertently removed the single big advantage a musket had over a longbow. Prior to the invention of gunpowder all weapons were powered by human and animal muscle. Your archers had to be in peak physical condition not just so they could sprint around the battlefield, but also to be able to shoot more than a few arrows before having to stop and rest. Quivers rarely held more than twenty shafts since after that the archer was too tired to shoot anyway. Once gunpowder became easily available, soldiers could shoot projectiles with far more energy, and do it all day long, because the power to run the weapon was stored in the ammunition, not in the body of the wielder.
Now, with your system, the user of the weapon has to channel magic back into it in order to recharge for the next shot. Where does that energy come from? If you make magical energy too cheap, then the important question becomes, "Why don't we have flying juggernauts raining down death from above?" If you make it too expensive, then your soldiers will become exhausted from channelling power into their weapons after ten or twenty shots, just like an archer, and the folks using black powder will clean their clocks.
Something else to consider: Loading times for muskets vary greatly with the skill of the user. A rank novice will manage about one shot a minute. A day or two's worth of training can easily up it to two/minute. A well-drilled soldier can reasonably be expected to manage three, and a savant can do four under ideal conditions. Is there going to be the same kind of progression with your magic guns? If there's not, then that shifts the advantage more toward the side with the better generals rather than the side with the faster shooters.
Also, as the technology progresses, expect someone to develop a version capable of storing energy for multiple shots and releasing them either all at once or in quick succession. See the volley gun, the puckle gun, and many examples of revolving pistols and rifles for examples. Yes, there were revolving flintlock pistols, Sam Colt's idea wasn't new, he just made one that was practical to mass-produce. Such things would likely only be in the hands of the aristocracy and wealthy merchants in the time period you're targeting though as the manufacture would be considerably more expensive and most people don't really need it.
I'm trying to figure out how much of an advantage these guns have over their real life counterparts, and what simple changes I may be able to make to keep them in line with their counterparts while keeping a similar feel to the weapon as described above.
I'd say the advantage is still ground-breaking.
Battles are won with guns, but wars are won with logistics. And you've created a gun which require no logistics at all. Now, your only endurance-limiting factor is the operator's human needs.
A regular army can advance only as much as their supply lines can stretch. Then they're cut off, run out of ammo and can't fire any more, ceasing to be a combat unit. Your army can advance as long as they keep finding food. A weapon that's never used in defense, because it really shines in offensive applications. You've basically created human equivalent of army ants that can keep pushing as long as they keep pushing. The only way they can be stopped is by larger force. But one force has to be the largest in the world - and they would be unstoppable.
What you need at strategic level is some limit. Eg make the musket being able to fire X shots and then stop, the only option left being remanufacturing. Or a time limit, like the polonium-210 laser rifle, which will lose it's juice whenever fired or not. This effect can be gradual, with newest weapons being the strongest and the oldest ones being little more than a distraction. This also opens new options, eg adding spent gunners to swell your ranks and appear bigger, also explains situations when a character is hit and incapacitated but not killed.
However, unlike real muskets that had to be manually loaded, these magical guns will recharge on their own without further action from the gunman.
A soldier with a magic musket can move after shooting, instead of reloading his musket. It is good for cavalry who adapt hit-and-run tactics. Also, it fixes the decay-over-distance of the magic projectile as cavalry can hit at close range and run away.
A normal musket has very poor accuracy due to its smooth barrel (a rifle fixes that). How about the magic musket? (You did not mention in the question.) However, I can assume that the magic projectile flies straight. So a soldier would not care about projectile ballistics.
Musketeers usually had a person that reloaded them the rifle. So they could use two. If you don't need to waste somebody times to reload that what stop you from having 4 rifles and shoot them one after another after another?
And you don't have problem with depleting your ammo pouch.
So, what you do? You create volley gun. You mother' flippin, frigin wall of barrels. Polish have created a 20-barrel gun. But somebeody had to spend time to load and reload them.
With your magic they don't need to do that.
So no need to worry about accuracy. If you fire 100 times you will probably hit the target at least once.
Accuracy might be a major difference... muskets were notoriously inaccurate, so a magically guided projectile could make a major difference (and if not the base model, someone will figure it out for the high end models).
Another difference might be in favor of the gunpowder musket. How long can a magic bullet remain in the chamber unfired? If the soldier has to concentrate for 30+ seconds while the magic charge is loaded, that would give advantage to a gunpowder musket soldier that is already loaded.
Another advantage for the magic bullets is the light discharged during firing at night would be smaller than a musket which has a bright flash and lots of smoke. I would think the magic bullet would produce less light (more like a pulse) but its also possible to make them about the same. Again this really only matters in nighttime battles, but that could be used to a major strategic advantage.
You should also consider different calibers of bullets. A sniper rifle has larger bullets and requires the greater mass in order for it to travel further. As you mentioned in your question, a magic rifle would degrade force and be more of an annoyance than deadly, but eventually some mage will figure out how to make a larger magic bullet that retains more force at a further distance. Of course this requires more magic (fewer shots per hour), but would be worth it.
Also consider the possibility of the magical equivalent of a cannon. It might require a team to supply all of the magic, but could have results just as devastating as gunpowder cannons. They would be possibly more accurate and certainly the materials would be lighter and easier to transport than a traditional cannon.
The advantage of the magically self-loading musket is that the operator can do something else while the musket is recharging. This allows some interesting tactics:
Another difference I haven't seen mentioned yet is that troops armed with magical muskets wouldn't be blinding themselves with clouds of gunpowder smoke. That becomes an even bigger advantage in this world than it would be in the real world since your magical rifles are more accurate and longer ranged.
Also, in reference to soldiers loading weapons multiple times between shots.. here's a bit of trivia I found interesting ( and kind of sad when you realize the stress and terror that caused it ):
After the battle of Gettysburg 27,514 rifles were found dropped or discarded. Of those, 12000 had been loaded multiple times.. with 6 thousand being loaded 3 or more times. 1 rifle was found to have been loaded 23 times.
Not a medically trained person here, but the effect being a localized fire blast should mean the wounds are always cauterized, shouldn't it? Which, as already mentioned, affects death by sepsis, but also reduces the chance to bleed out.
I always was under the impression a lot of kills from this era were due to blood loss, sepsis etc and an equally big impact was not due to killing, but disabling soldiers by way of badly set broken bones or other injuries that would not heal properly. Tightly localized fire blasts sound like a more superficial damage, badly scarring, incapacitating short term due to pain and taking time to heal, but if not immediately deadly then having less long time consequences. You might want to consult some medical folks on the different effects of impact vs. burn in injuries.
Normal muskets tend to make a lot of noise when fired. One cannot sneak into the place and use it to assassinate guards one by one. A magical musket could allow trained soldiers to be used for surprised attacks, capturing objectives in the night or breaking into highly secure areas.
What's more, with unlimited ammo, it would make perfect survival weapon. An animal, if you would even miss it, won't even run away, as there is no sound nor projectile that can scare it away.
Everybody who would be trained well enough to sneak near a human or animal could kill it with no consequences. It's like an easier to use blowgun with musket range and unlimited ammo. No one is safe with those around!
Forewarning: I am not a student of cavalry tactics nor military history.
Cavalry equipped with firearms would often fire once, then stow their weapons and charge, or retreat to reload, or dismount and fight on foot. Cavalry equipped with magic muskets would have the ability to sit just outside of musket effective range and rain fire onto enemy lines. Cavalry could either be organized more loosely to avoid cannon fire or could fire on the run, if accuracy allowed it.
Scouts and Irregulars
Some of the first use of rifles was in the hands of scouts and skirmishers. I believe that these groups would be among the first to get their hands on the magick muskets. Imagine scouts equipped with weapons that required no ammunition, reloaded themselves over time, had longer range, were more accurate, and did not produce any smoke. If you had two of these weapons (and soldiers did carry multiple muskets), you would be able to double your rate of fire with very little sacrifice. Your scouts would be able to move more freely, stay out in the field longer, and remain concealed when firing (including, as previously mentioned, staying prone).
Scouts or skirmishers would immediately be better suited to hiding in the woods, ambushing supply trains, attacking foraging and scouting parties, and sniping officers. If you can engage an enemy without risking significant losses, you stand to gain the upper hand even before battle is met.
How does the enchantment work? Does it create recoil when fired? Is the barrel enchanted, or the gun as a whole? Whatever the details are, I bet you can find a way to create weapons with multiple barrels. This could be anything from a double-barrel musket to a volley weapon to a gattling gun. While these weapons would require more work, it would be difficult to deny their battlefield effectiveness, especially in a time when black powder rifles and tight formations are still in use.
Secondly, how does caliber and grain affect the weapons. Is the barrel of fixed dimensions, or can you have little pea-shooters and huge cannons? Does muzzle velocity affect the damage the bolt does, and does the bolt decelerate with drag and drop with gravity? Can you crank up the 'grains' in your enchantment, and get the equivalent of a high-power rifle as compared to your average, normal 'grain' count rifle? Depending on the answers to these questions, you could end up with completely different weapons.
You haven't specified whether your "magic bullet" is affected by wind or gravity; on the assumption that they are not so affected, they will have the advantage of not needing to account for distance (beyond the question of dissipation) or weather conditions.
They will also have the disadvantage of not having to account for distance or weather conditions, if the same musketeers may be required to use magic muskets at some times, and powder muskets at others.
If there is any sort of capability for suppressing magic over an area, the magic-musketeers may suddenly find themselves disarmed, when they go into an area where magic is suppressed. Unless there's a similar magical ability to suppress the chemical reaction that black powder uses, the powder musketeers will have the advantage under those conditions.
If this is the best they can do with magic right now, it will quickly be outclassed because guns have a lot of room for improvement past the musket.
The thing holding back the guns is mechanical evolution/invention, but unless magic was very recently introduced I'd assume they would be able to use it quite effectively already since they had most likely always had access to it.
If I were some mage inventor I would probably be going down a different road--perhaps enchanting existing musket-balls to seek their target or have them spread some sort of contagion that will infest the enemies. Solutions that take less magic "Power" and use a little more finesse/creativity--maybe ammo that can phase through the first two inches of solid material it comes in contact with or one designed just to distract the troops--for instance creating extremely bright flashes that can blind...
Just flew over the answers and wanted to add another point I didn't see mentioned (might have just missed though)
You say your magic guns do fire and lightning damage. Those effects however change in certain situations and under the influence of the elements. A battle in rain might have a very different outcome than that on a sunny day.
Electricity damage is a tricky thing anyway.
People would probably try to find ways to reduce these effects like creating isolating clothes, a Faraday cage as armor or anything along these lines.
There are also some advantages to getting hit by electricity rather than a projectile. You don't have to deal with foreign particles in your body, no surgery needed to cut them out, you don't have to deal with blood loss, shattered bones and internal bleeding killing you hours later.
Fire might enflame the body (look up the wick effect), work less effective in rain, may also cause a sepsis, result in the unclean smoke you got with regular muskets, well ... we do have weapons in our modern arsenal working mainly with fire.
As I'm neither an electrician (I did study technical informatics, though. So we had some subjects closely related to electrical engineering) nor a doctor and mostly looked things up I won't go any deeper but you might want to do so in order to keep it realistic. Or just go with magic damage.
Something I'd like to point out here, as an infantry veteran, is the psychological factor of superior weaponry. The job of the infantry is to dominate your enemy physically and psychologically, and the bigger and louder and more efficient your weapons, the more this starts to unnerve the enemy and affect them in combat. If these magic muskets were not commonplace (for example like real muskets back in the day -- flintlocks were illegal to own for civilians for some time), it could be quite psychologically daunting to be a soldier or civilian going up against a unit armed with magic muskets. Especially if they've never seen them before, or haven't handled or fired them personally; they have nothing but legend and reputation to fuel their thinking as they march into battle. This is actually a Very Big Deal in combat, and can definitely sway a battle one way or the other.
The biggest difference is that they reload on their own. Thus troops will carry multiple of these mamuskets and swap them between shots for a higher rate of fire.
So forget about the majority of the users being inadequately trained conscripts - these get the cheaper weapons like bows, knifes, and shields, while the trained marksmen get 5 mamuskets each.
Speaking of shields, your mamusket seems to do rather poorly against shield walls. While the heat and electricity may be useful against worn metal armor, it seems to be pretty much useless against metal shields.
Advantage: High rate of fire.
Disadvantage: High cost (5 muskets for 1 soldier), can be countered by specific equipment and formation (shield wall).
Another advantage is that it's trivial to advance the technology to the point of gatling mamuskets.