Feed from the mag
To the best of available information, none of the service style autoloaders is intended to be a push feed. They aren't built like a Remington 700. Or an AR-15. They are intended to have rounds fed up underneath the extractor claw, kind of like a mauser.
Can you drop a round in the chamber and get away with it? Most guns yes, once. Some guns alot. Others not. Should you? NO! I would consider it something to be done only in gravest need.
Check your owners manual, or direct with the manufacturer, if they don't specifically authorize this kind of opreation, then you are running a risk. 1911s are particularly vulnerable to damage from this practice, but they are not the only ones. I have one owner's manual that specifies NEVER to load their gun in this manner, it could result in discharge!
Load the mag. Feed from the mag. The mag is our friend.....
While it may not be necessary it is the best practice.
ITEOTWAWKI gave a link to a thread on this very question. Check it out, he saw the light, you should too.
Need a gun that you can do this to, in case you lose the mag? Buy a revolver! Cause if you lose your only mag, your autoloader is pretty much out of it. Oh, you can still fire single shots...yep, and after you lock the slide back by hand, you can reach in with your fingernail, or your pocketknife, or a screwdriver, or a pen, etc, and pluck out the empty. Take you maybe 2-3 seconds more because you were a total idiot, and not only lost your only mag, but broke your extractor as well. And where is the ammo you are carrying to load your new single shot? It's in a box? Loose in your pocket? Why isn't it in a spare mag????????
Saying that the Govt required the ability in the 1911 so the pistol won't be "usless" if you lost the mag might be true. But it is a useless requirement. On the other hand, Govt has a long history of putting useless requirements in their procurement process. So it could be true.
And isn't (at least some parts of) Govt today requiring a magazine disconnect? So the gun can't fire without the mag? That one is not only useless, for a service pistol, it is potentially dangerous.