Thumb Safeties
One of the first custom parts on the market, the extended thumb safety has become a standard item on many factory stock pistols. I tend to believe it's origins come from some gunsmith or armorer back in the 1920's working with the original GI "tiny tab" safety and having a hard time manipulating it. He might have fixed the problem by soldering on a little piece of steel to make it easier to operate. Since that time, parts manufacturers have produced a great variety of shapes and sizes in both single-sided and ambidextrous versions. Below, we'll take a look at the current market offerings.

Single sided extended safeties
Good quality safeties are available from Ed Brown, Wilson and EGW. The Ed Brown safeties and some of the Wilson safeties are made from the investment casting method. The EGW and a couple of recent releases from Wilson are made from barstock. They are all of adequate quality and utility; and selecting one over the other is mostly a matter of personal preference. Most of these are available with a narrow (or "tactical") or a wide thumb shelf. Personally, I find the narrow versions just barely wide enough and the wide ones too wide. My most popular safety offering is a wide one, reshaped to a medium Carry Contour.

I take great pains to relieve the sharp corners on the safeties to help reduce shooter discomfort and abrasion to the hand. I prefer to adjust the detents to require a firm snap off to disengage the safety and a little less force to re-engage. I think this works well since you use the top of the thumb to engage and nearly everyone shoots with his or her thumb riding the safety. I still want adequate force to be there to prevent accidental engagement if shooting with the left hand.

Ambi Safeties
Ambi safeties make the pistol easier to use with either hand and are pretty much a must have for the southpaw. They are nice for "righties", but not mandatory. Everything that I said about the single sided safety applies equally to the ambi. Right-handers probably make more use of an ambi safety during USPSA matches, than any other conceivable use, due to mandated "weak hand" use specified in certain courses of fire. The weakest point of the whole ambi concept is the joint that attaches one side to the other.

When Armand Swenson came up with the ambi concept, he used a "tongue and groove" joint in the middle of the shaft, hidden by the grip safety. The half of the safety on the right side of the pistol is retained by a firm fit in the joint and a flat leg that slips beneath the right hand grip panel. This arrangement works pretty well for a right-handed shooter, who occasionally fires left handed. Experience has taught me that for constant left-handed use, a couple of extra steps need to be taken to keep the two halves from working loose.

The thumb shelf on the right side must be fit so it bears either against the top of the right hand grip panel or must have a stop stud installed into the frame for the shelf to bear against. The joint must be a tight fit and the flat leg must not be sloppy under the grip panel. One way or another, you have to set it up so that when the lefty disengages his safety and then rides the top of the shelf, the force is transmitted to something that stays on the right hand side of the frame, rather than transferring through to the other side of the gun. The King's ambi uses a special hammer pin to retain the right side ambi. It's constructed with a dovetail on the right hand end of the hammer pin that engages a matching groove in the backside of the right hand half of the safety, keeping the safety from moving out from the frame.

Thumb Guards
Everyone's hands are of different sizes and there are a lot of subtly different ways of gripping the gun. Some shooters have the problem of their thumb that they have riding on top of the safety, also rubbing the side of the slide. In some cases, this can actually cause the slide's speed to be retarded, making the gun malfunction. To stop these malfunctions, gunsmiths have designed and installed thumb guards to shield the slide from the thumb's pressure. Some are made as part of the thumb safety, some are made as part of the plunger tube and some are just sheet metal flaps, retained under the grips. Thumb guards are not a part that I would add to a gun, unless the shooter is really having the problem just described.

Thumb safeties and how they relate to the hammer and sear
Thumb safeties come from the manufacturer with an oversize fitting point on the stud that blocks the sear's movement and keeps the sear from moving out of engagement with the hammer hooks. When a new safety is installed, it won't fit into the gun, requiring this fitting pad to be filed down until the blocking stud fits so that the sear can't be moved at all, yet the safety can be installed in the gun. So, in effect, the thumb safety is fit to a particular set of parts, the frame, pins, hammer, disconnector and sear. When some of the parts in this set are replaced or a trigger job is done, the relationship between the fitting point on the blocking stud and the sear may change. Sometimes a little more will need to be filed away from the existing fitting pad, sometimes it'll be just right and work as-is and sometimes it has to be welded up and re-fit to remove any clearance between the stud and the sear. The reason that I weld and re-fit is that the only other option is to replace the safety with a new part.