[Double Naught Spy]

" Tackle " implies a running grab and throw, I'd think this is more of a generic description in the press than a accurate sequence of events. ( The Jack Ruby take down comes to mind as distance to others was near zero )

Your definition fits well for how it is used in football commonly, but even in football, the person making the tackle need not be running. However, if you disagree, then just read the word "tackle" in this thread as meaning the act of forcibly taking a person to the ground which is the action being performed by those in the examples provided.

It takes more than getting the shooter on the ground, their gun hand must be disabled.

Nobody has suggested that the fight ends once the shooter is grounded, but grounding the shooter is a first major step to regaining control of a situation and preventing the shooter from being able to continue shooting at will. Instead of shooting at targets of opportunity, the shooter will focus on gun retention and trying to get free of the tackler(s). Getting the shooter on the ground greatly limits the shooter's mobility, line of sight, and directions of aimed fire. In short, tackling the shooter reduces his realm of command that encompassed a very large area while free firing to a very small area for which the shooter has to fight to have any control. Once the shooter is down, the amount of danger posed of the shooter is greatly reduced.

I don't think any of the examples I have listed resulted in the gun hand of the shooter being disabled. Guns were taken from shooters, shooters weren't allowed to reload, guns/hands were controlled such that the shooter could not shoot at targets...but none had their hands disabled.

Just a little tid bit for those who CCW. Any practice done at the 7yrd line and closer should include instinctive style shooting from in close and at the hip. Outstreched arms turn 21ft into 17ft.

You have arms 4 feet long?

A person can cover a lot of ground in the time it takes another to react.

Absolutely, but it is relative to what sort of reaction needs to be effected. The Tueller Drill showed how officers could be successfully stabbed by an attack who started from 21 feet away and charged the officer. The officer could not draw and fire in that amount of time...which was about 1.5 seconds. With his gun out, say at low ready, the officer could land shots ont the attacker in less than half a second. With the gun pointed at the bad guy, he could be shot in a quarter of a second or less from the start of his attack.

That is why timing is critical. The shooter has a much greater chance of shooting somebody charging at him if his gun is out and firing than if his gun has malfunctioned or it is while he is reloading. Depending on his gun handling skills, most such shooters are not likely to change magazines in less than 4 or 5 seconds - the time from last shot of old mag to first shot of new mag. That is a long time.

Yes, some shooters may be more skilled and quicker. We have all seen the guys with race guns and speed rigs do amazing mag changes. Rob Leetham isn't likely to be your active shooter. In several events such as AZ, Luby's and VT, the shooters had spare magazines in pockets that they had to fish out and orientate.

Something heavy will surely knock a shooter off balance.

Well and Loughner was struck with a chair. The blow wasn't huge, but it did put him off balance and both of his tacklers noted it was extremely beneficial to their success.

The effectiveness of such attacks can be quite variable. How they get perceived often relates to how well they changed the situation. The lady hitting the gunman's hand with her purse at the Florida school board meeting was perceived as being terribly ineffective. The gun wasn't knocked from his hand and nobody else responded to the distraction, even after the gunman turned his back on the rest of the school board to deal with the lady. Had a couple of the school board guys tackled the gunman at that point, the purse attack would have been credited to the gunman being taken down.