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Assorted Technical Stuff
The difference between a Picatinny Rail and a Weaver mount (courtesy of the folks at Brownells):
The “Picatinny Rail” is a term that has evolved in the firearm industry from a military standard, specifically MIL-STD-1913 (AR) which was adopted on February 3, 1995. The title of the publication is “Dimensioning Of Accessory Mounting Rail For Small Arms Weapons” and this document specified exactly what the dimensions and tolerances were for any mounting systems that were to be submitted for acceptance by the military. The term “Picatinny” comes from the place of origin for this system, the Picatinny Arsenal located in New Jersey. MIL-STD-1913 specifies the dimensions required for consideration, including length, width, height, and angles and the tolerances allowed for each measurement. The key distinction of the MIL-STD-1913 lies in the specification for the profile and the recoil groove.
Source: MIL-STD-1913 (AR) 3 February 1995
Source: MIL-STD-1913 (AR) 3 February 1995
What are the differences between the “Picatinny” and the “Weaver” systems? The profile of the two systems is virtually identical. Depending on the quality of the machining done by the manufacturer, the two systems should be indistinguishable from the profile. The key difference lies in the placement of the recoil grooves and with width of the grooves. MIL-STD-1913 (Picatinny) grooves are .206” wide and have a center-to-center width of .394”. The placement of these grooves has to be consistent in order for it to be a true “Picatinny” MIL-STD system. Weaver systems have a .180” width of recoil groove and are not necessarily consistent in a center-to-center measurement from one groove to the next. In many instances, a Weaver system has a specific application that it is machined for, so interchangeability is not necessarily an issue. A MIL-STD-1913 system must adhere to the specifications listed above in order for it to be considered MIL-STD, since the military desires uniformity in the recoil grooves to allow for different systems to be mounted on the weapon with no concern for compatibility.
Now, what does this mean to you? Boiled down, it means that accessories designed for a Weaver system will, in most cases, fit on a “Picatinny” system. The reverse, however, is probably not the case. Due to the larger recoil groove, “Picatinny” accessories will not fit a Weaver system. There are, of course, exceptions to every rule, but for a good rule-of-thumb, “Picatinny” won’t fit Weaver, but Weaver will fit “Picatinny”.
The Conditions of Readiness:
The legendary guru of the combat 1911, Jeff Cooper, came up with the "Condition" system to define the state of readiness of the 1911-pattern pistol. The are:
Condition 0 - A round is in the chamber, hammer is cocked, and the safety is off.
Condition 1 - Also known as "cocked and locked," means a round is in the chamber, the hammer is cocked, and the manual thumb safety on the side of the frame is applied.
Condition 2 - A round is in the chamber and the hammer is down.
Condition 3 - The chamber is empty and hammer is down with a charged magazine in the gun.
Condition 4 - The chamber is empty, hammer is down and no magazine is in the gun.
The mode of readiness preferred by the experts is Condition One. Generally speaking, Condition One offers the best balance of readiness and safety. Its biggest drawback is that it looks scary to people who don't understand the operation and safety features of the pistol.
Condition Two is problematic for several reasons, and is the source of more negligent discharges than the other conditions. When you rack the slide to chamber a round in the 1911, the hammer is cocked and the manual safety is off. There is no way to avoid this with the 1911 design. In order to lower the hammer, the trigger must be pulled and the hammer lowered slowly with the thumb onto the firing pin, the end of which is only a few millimeters away from the primer of a live round. Should the thumb slip, the hammer would drop and fire the gun. Not only would a round be launched in circumstances which would be at best embarrassing and possibly tragic, but also the thumb would be behind the slide as it cycled, resulting in serious injury to the hand. A second problem with this condition is that the true 1911A1 does not have a firing pin block and an impact on the hammer which is resting on the firing pin could conceivably cause the gun to go off, although actual instances of this are virtually nonexistent. Finally, in order to fire the gun, the hammer must be manually cocked, again with the thumb. In an emergency situation, this adds another opportunity for something to go wrong and slows the acquisition of the sight picture.
Condition Three adds a degree of "insurance" against an accidental discharge since there is no round in the chamber. To bring the gun into action from the holster, the pistol must be drawn and the slide racked as the pistol is brought to bear on the target. This draw is usually called "the Israeli draw" since it was taught by Israeli security and defense forces. Some of the real expert trainers can do an Israeli draw faster than most of us can do a simple draw, but for most of us, the Israeli draw adds a degree of complexity, an extra step, and an opening for mistakes in the process of getting the front sight onto the target.
Using the "half-cock" as a safety
The half-cock notch on the M1911 is really intended as a "fail-safe" and is not recommended as a safety. However, it has been used as a mode of carry. From Dale Ireland comes this interesting piece of service history from WWII:
When the hammer is pulled back just a few millimeters it "half cocks" and pulling the trigger will not fire the gun [on genuine mil-spec G.I. pistols]. I imagine this is an unsafe and not a recommended safety position. The reason I bring it up however is that it was a commonly used position especially by left-handers in WWII. My father carried his 1911 (not A1) to Eniwetok, Leyte, first wave at Luzon, the battle inside Intramuros, and until he was finally shot near Ipo dam. He tells me that he regularly used the half cocked safety position especially at night and patrolling because bringing the weapon to the full cocked position from the half cocked created much less noise and he was left handed so he couldn't use the thumb safety effectively. He said using the half cocked position was all about noise reduction for lefties while maintaining a small amount of safety that could quickly be released.
Again, the half-cock is intended as a fail-safe in the event that the sear hooks were to fail, and it is not recommended as a mode of carry. It should also be noted that on guns with "Series 80" type hammers, the hammer will fall from half-cock when the trigger is pulled. This would include guns from Springfield Armory and modern production Colts. But, if you happen to be a south paw and find yourself in the jungle with a G.I. M1911A1 and surrounded by enemy troops, the half-cock might be an option.
For more detailed discussion of the safety and internal functions of the M1911, see "Is Cocked and Locked Dangerous?"
Popular firearms forums:
M1911A1.org - For all the 1911 fans out there.
XD Talk - Forum for HS2000/Springfield XD.
AR15.com - Black rifle forum.
SAFETY CHECK PROCEDURE:
Safety/Function Checking a 1911A1 (pdf)
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