I recently decided it was time to up my game and drill more seriously on skills I don't have.
Tactical reloads are definitely a weak spot for me...so I have been practicing them more.
I load up a few mags with a single round and just run through them as fast as I can while trying to stay on target.

In terms of mechanics, I use my weak hand to gently pull back on the slide to send it into battery (rather than using the slide release)
I've seen people preach both methods, but for me it doesn't seem to be faster one way or another.
Curious to get your opinions on this.

As far as dropping the empty mag...in my case I am shooting a primary weapon that doesn't always drop the mags free...I've found that to be 100 positive I use my weak hand to pull the mag out of the grip and drop it as I go for the reload. When I fire the last shot and slide locks back, strong hand engages the mag release, weak hand falls, pulling the empty mag on the way, weak hand grabs new mag and brings up to insert it, and then palms the top of the slide and pulls to the rear and lets go, returning to gripping the weapon, then target acquisition. Maybe I just suck at this right now and am clumsy still, but it feels like there is a lot of movement. Is this something that will likely improve with reps, or is there a better order of operations that would be more efficient?

The weapon in question is a S&W M&P full size, using factory 15 round mags.

Thanks for any advice

What you’re talking about is a speed or emergency reload, not a tactical reload.  A tactical reload is when you have a pause in shooting and still have a round in the chamber and are “topping off” your gun by grabbing a full magazine and swapping it at the gun with a partially-used magazine.  This ensures the gun is at full capacity in the event your gunfight continues.  The used magazine is retained for later use.  A speed reload is where you have a round in the chamber but dump the magazine and let it fall free, not retaining it, and insert a fresh magazine to top off the gun faster than you could with a tactical reload.  An emergency reload is when your gun runs dry and you do a normal mag reload.  Speed reload terminology is often used interchangeably, and often times people will clump both together speed and emergency terms and just call it a speed reload.  This simplifies it so that a mag retained is “tactical”, and mag left to drop free is “speed”.  It’s arguing minutiae, but the point is, what you’re referring to is not a tactical reload.  But you should practice those too.  

Yes, you’re losing time in stripping the magazine.  That doesn’t need to be done unless it is actually needed due to a sticking magazine.  The instant that you go dry, you should be multi-tasking your hands.  Strong hand ejects the magazine while the weak hand immediately goes to the spare magazine.  Based on your timing, you should be grabbing your reload mag while ejecting the old mag from the gun.  The way we explain it to students in the police academy, we ideally want the mags passing each other in mid air.  

Your magazine reload location is relevant, as is the type of magazine pouch.  Open-top pouches are faster than pouches with flaps, and different pouches have different levels of retention or the ability to adjust retention pressure.  The orientation of the magazine can be a factor depending on how you grab it, which is affected by the way the mag pouch is oriented and where on the body it’s affixed.  A lot of factors can affect how fast and efficient you can pull the magazine from the pouch.  This is something that can be overcome by training, but through your training you’re going to fine-tune your setup until you find what works best.  

Overhanding the slide to release it does take longer than just dropping the slide using the slide lock lever.  You can check this by using a shot timer, but in the police academy, we put students on the clock and show them the difference.  The reload procedure should be that as you insert the fresh magazine, you then move your weak hand to regrip the gun and push the gun forward back on target.  At the same time as you are regripping, you are dropping the slide using the lever.  Compare that to inserting the magazine, then reaching over the top of the slide, pulling it back and releasing, and then moving down to regrip.  When you do the overhand method, you are adding 2-3 extra movements.  Added movement means added time.

Overhanding is functional, but it’s not necessary unless you have a medical (i.e. arthritis) or mechanical (broken lever) reason for not using the slide lock lever.  The lever is faster, as it’s more efficient.  If you just prefer to run your gun that way, then that’s okay too and practice will help you get faster.  Just know that there is no benefit to running the overhand method.  The main reason why the overhand method has been pushed in the past is the false belief that people can’t use their thumbs under stress, but magically could still use their trigger fingers.  

The ultimate factor is REPETITIONS.  Nothing is going to magically come.  You just need time and repetitions.  Time adds up to produce results, but every time you change something, you reset backward to a certain level as you have to relearn a new methodology.  What you are really doing is developing neural pathways.  It’s called automaticity, and also known as repetitive task transference.  More colloquially, it’s called “muscle memory”.  You have to condition your brain to make your body move efficiently and quickly, and that comes with time.  Basically, just keep at it with the practice.

Thank you

What he said.

My only point of contention is that I have seen it way too many times, mags don't always drop free. I've had it happen to myself. I watched some guy jam his finger in between two mags at full blast because the empty decided to hang around.

I prefer to forcibly remove my magazines, empty or not. I do not trust them to come free. While the weak hand is leaving the firing grip, it swipes over the magwell, and if necessary takes the empty with it on the way down to pick up the fresh mag. Right about when the hand gets to belt line, release.

While of course I tout this as the reliable method, never will I argue it as faster. Until you're fiddlefucking a stuck mag with one in your hand and the timer (be it the one that beeps at you or shoots back) going. I accept the liability of being a bit slower verse the dice roll of certain loss.

The same methodology goes for reloading an AR15 or similar rifle. I pull the empty out.