3 words: FIRING PIN BLOCK
AKA a solution in search of a problem. This "lawyer friendly" mechanism is supposed to prevent "accidental discharges" caused by dropping the pistol or catastrophic mechanical failures that never happen.
Series 80 FPB (Colt, Para, SIG, Taurus):
This firing pin blocking mechanism on the Series 80 Colts differentiates the Series 80 Colts from the "true" M1911A1 pistols. The M1911 and M1911A1 pistols do not have this device. The purpose of the firing pin block is to prevent the firing pin from moving forward unless the trigger is depressed. The Colt Series 80 uses two little levers that are moved by motion of the trigger that lifts the block from the firing pin in the slide.
Many 1911 fans rightly complain that this firing pin block adds some mush to the trigger pull. For us, there is no such thing as a match grade Series 80 trigger. Glock fans won't notice a thing.
In addition to Colt Series 80, Para, SIG 1911 and Taurus are Series 80 based.
Swartz FPB (Kimber Series II, S&W 1911):
In 1937, William L. Swartz designed a 1911 firing pin safety with no connection to trigger components. It was operated by the action of the grip safety. Today, examples with the Swartz safety are scarce collector's items, for Colt didn't make many. This safety disappeared with the onset of WWII and a FPB was not seen on 1911s until the Series 80s.
Enter the Kimber Series II. In response to the needs of law enforcement agencies - which frequently mandate a firing pin safety - Kimber brought back the Swartz design. When you depress the grip safety, a small pin pushes a plunger up in the slide which unblocks the firing pin. The good news is that the smooth 1911 trigger pull stays the same, the bad news...
You have to be careful when you field strip and reassemble a Series II Kimber because if you hold it by the grip and activate the grip safety, a little pin comes up next to the disconnector and it will stop the slide from coming off or going on. This is a PITA since your instinct is to hold the gun by the grip. The natural reaction to unsticking a slide while field stripping is to use force. Use enough force on a Kimber Series II with grip safety depressed and you shear the pin, rendering the gun useless (ie. no pin, no bang).
Also, the FPB mechanism can only be accessed by removing the rear sight should you need to do cleaning or maintenance on it. Yuck.
All platforms utilizing the Swartz safety are a less than ideal choice across the board due to the inherent reliability problems of the design. The Swartz safety is extremely sensitive to the fit of the grip safety to the frame and the timing of the grip safety's trigger blocking arm. Tolerance issues can also lead to a Swartz safety that will time properly when the grip safety is depressed a certain way, and time differently when depressed a different way. This will typically be a product of loose fit of the grip safety to the frame tangs and/or loose fit of the thumb safety shaft through the grip safety. It is possible to have the grip safety timed such that the trigger will be able to release the sear well before the firing pin safety plunger has been moved far enough to clear the firing pin. Problems with improper timing of the Swartz safeties can lead to a situation where you get a "click" when you wanted a "bang." The US Army knew what it was doing when it dropped the Swartz for WWII.
SW1911s use Swartz as well.
AKA a solution in search of a problem. This "lawyer friendly" mechanism is supposed to prevent "accidental discharges" caused by dropping the pistol or catastrophic mechanical failures that never happen.
Series 80 FPB (Colt, Para, SIG, Taurus):
This firing pin blocking mechanism on the Series 80 Colts differentiates the Series 80 Colts from the "true" M1911A1 pistols. The M1911 and M1911A1 pistols do not have this device. The purpose of the firing pin block is to prevent the firing pin from moving forward unless the trigger is depressed. The Colt Series 80 uses two little levers that are moved by motion of the trigger that lifts the block from the firing pin in the slide.
Many 1911 fans rightly complain that this firing pin block adds some mush to the trigger pull. For us, there is no such thing as a match grade Series 80 trigger. Glock fans won't notice a thing.
In addition to Colt Series 80, Para, SIG 1911 and Taurus are Series 80 based.
Swartz FPB (Kimber Series II, S&W 1911):
In 1937, William L. Swartz designed a 1911 firing pin safety with no connection to trigger components. It was operated by the action of the grip safety. Today, examples with the Swartz safety are scarce collector's items, for Colt didn't make many. This safety disappeared with the onset of WWII and a FPB was not seen on 1911s until the Series 80s.
Enter the Kimber Series II. In response to the needs of law enforcement agencies - which frequently mandate a firing pin safety - Kimber brought back the Swartz design. When you depress the grip safety, a small pin pushes a plunger up in the slide which unblocks the firing pin. The good news is that the smooth 1911 trigger pull stays the same, the bad news...
You have to be careful when you field strip and reassemble a Series II Kimber because if you hold it by the grip and activate the grip safety, a little pin comes up next to the disconnector and it will stop the slide from coming off or going on. This is a PITA since your instinct is to hold the gun by the grip. The natural reaction to unsticking a slide while field stripping is to use force. Use enough force on a Kimber Series II with grip safety depressed and you shear the pin, rendering the gun useless (ie. no pin, no bang).
Also, the FPB mechanism can only be accessed by removing the rear sight should you need to do cleaning or maintenance on it. Yuck.
All platforms utilizing the Swartz safety are a less than ideal choice across the board due to the inherent reliability problems of the design. The Swartz safety is extremely sensitive to the fit of the grip safety to the frame and the timing of the grip safety's trigger blocking arm. Tolerance issues can also lead to a Swartz safety that will time properly when the grip safety is depressed a certain way, and time differently when depressed a different way. This will typically be a product of loose fit of the grip safety to the frame tangs and/or loose fit of the thumb safety shaft through the grip safety. It is possible to have the grip safety timed such that the trigger will be able to release the sear well before the firing pin safety plunger has been moved far enough to clear the firing pin. Problems with improper timing of the Swartz safeties can lead to a situation where you get a "click" when you wanted a "bang." The US Army knew what it was doing when it dropped the Swartz for WWII.
SW1911s use Swartz as well.