[cracked butt]

the safety locking the slide closed?

[mfree]

I don't own a 1911 or clone, but I'd say maybe it's to keep the slide from coming out of battery when holstered?

[WhoKnowsWho]

It also helps with disassembly when you push on the recoil spring plunger, you don't want the whole slide moving back too.

[OF]

I don't know if it's the original intent, but what mfree mentioned is what I've found to be the best part of that feature. When I holster my USP, I have to hold the slide forward with my thumb as the gun goes in. With the 1911, it's all taken care of. :)

Reason #57 I love the 1911 more than any other pistol design.

- Gabe

[cracked butt]

That was my first inclination too, but it seemed too obvious, and I haven't seen the same feature on other handguns.

[ssr]

You referring to the thumb safety?

The purpose isn't to necessarily lock the slide, but to keep the pistol from firing. It may click up and fix the slide closed, but it also keeps it from firing, even with the grip safety depressed and trigger pressure applied.

[Lochaber]

I am sure that the stated reasons are true, but I also like the fact that it also acts as a dumba** break. I can imagine that in the heat of combat one could pick up a gun rack the slide, see the cocked hammer and assume he is ready to go, while the safety is still on, which could be a bad thing.

I like to think of it in terms of the classic Mauser safety. When fully locked it locks up the bolt and the trigger, but in the half lock where you can manipulate the bolt but not the trigger it blocks your view of the sights and thus is gives you an indication that your gun is not yet ready to fire. Hard to do that with a pistol, so I think it is a good choice to lock the slide on safe. Btw, other firearms do the same, like the CZ.

Loch

[BluesBear]

I believe most of John Browning's pistols utilized safeties that locked the slide.

In the 1911 design when the hammer is down the increased pressure applied by the hammer/mainspring helps hold the slide in battery.
When it is cocked and locked the safety then locks the slide into battery.
This does aid in holstering the weapon.

If the slide was moveable in Condition One, it would be possible for debris of some kind to find its way into the weapon thus preventing it from going into battery and firing when needed.

[Old Fuff]

B-Bear is correct. All of Browning's pistols, both those made by Colt as well as Fabrique Nationale (FN) lock the slides closed in battery when the safety is "on." The reason is to be sure the slide is in battery and ready to fire when the safety is moved to "off," and to be sure that once the safety is applied the pistol stays that way. Otherwise a slight push on the muzzle could move the slide far enough out of battery so it wouldn't fire.

[yankytrash]

I thought it was so cavalry wouldn't have AD's when charging on their horses..?

Aa, whatever. I'm easily confused sometimes. Might be thinkin of something else.

[1911Ron]

If i'm not mistaken the thumb safety was added at the Armys request, the Cavalry wanted it added so when mounted it could be carried condition one. The lanyard loop was added so they could attach a lanyard and not loose the pistol.

[Detritus]

If i'm not mistaken the thumb safety was added at the Armys request,

this is correct, at least one of the inital prototypes sumbmitted early in the process did not have the thumb safety (this example is still extant btw). as stated, the cavarly lobbied for the thumb safety due to having a MUCH higher likelihood of of an AD if such a device was not included, than say the infantry.