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Building a Low Buck Shooter -
Part III
Thumb Safety Upgrade
By
Joseph D'Alessandro Editor |
RealGuns.Com
 At the conclusion of Part II, the High
Standard GI 1911 had been fitted with a lightweight
trigger and upgraded with a new disconnector, hammer and sear. A
light mainspring had also been installed. The end
result was a clean, light trigger pull and greatly reduced trigger
bounce. Five shot groups were tightening through improved shooter control and the
gun was taking on a more substantial personality.
Next up is an upgraded thumb safety. Why change a thumb safety?
Pictured, top, is a standard safety and, lower, a tactical
style extended safety. The extended safety is much easier to
operate without disturbing the shooting grip and, in a high hold, it
makes a nifty place to rest a thumb. Some safeties are
wider than other and some are set at different angles. There are,
of course, ambidextrous versions of the same safeties that permit operation from either
side. I selected the Ed Brown tactical style safety, Brownells
087-245-890, which is designed for concealed carry, $29.95.
The Ed Brown tactical is also available
in stainless for $2 more and in ambidextrous models for approximately
$55. Below, left to right, are some other alternative available
through Brownells. Wilson
Combat High-Ride Ambi Safety $58 blued, $59 stainless. Nighthawk
Custom Extended Thumb Safety $43.95. Wilson Combat Extended Wide and
Narrow thumb safety $31.50 either model in blue or stainless.
Disassembly in Summary Form
Regardless which specific type of thumb
safety selected, the fitting work is minor, but critical, and
essentially the same for all. If you are unfamiliar with disassembly
of the 1911, I suggest picking up a copy of The Colt .45 Auto
Automatic shop manual by Jerry Kuhnhausen from Brownells. $28
and saving yourself a lot of grief. The 1911 is easy to disassemble,
but it is pretty picky about the sequence followed. It is possible
to disassemble incorrectly so the thumb safety can't be removed.
If you fly, or if you spend much time
around aircraft, you're familiar with check lists for even simple
tasks. The concept is that people can make mistakes in completing
simple and routine tasks through mental lapses. Following a step by
step check list in a disciplined fashion minimizes that problem.
You might want to make a critical check list to keep on your bench.
You can begin with, "Pull the magazine and check the chamber for empty
befor attempting any
service on any gun".
The slide assembly can be removed either under load
or with the recoil spring unloaded. I prefer the latter. The recoil
spring plug is depressed and held in place as it is under load. The
bushing is rotated clockwise to clear the plug, then the plug is
eased forward until it is no longer under load. The recoil spring is
removed. It is easier to remove if rotated clockwise while being
lightly pulled forward from the recoil spring guide inside the gun.
With the plug and spring removed, the barrel bushing can be rotated
counter clockwise, unlocked and removed from the gun.
With the slide unloaded, the hammer is cocked and the
slide pulled back until the curved notch in the slide, arrow, is
aligned with the vertical tab on the right side of the slide stop.
The slide stop is pushed out of the gun by depressing the slide stop
pin from the opposite side of the gun. With the barrel no longer
connected to the frame by the slide stop and barrel link, the slide
can be moved forward and off of the frame.
 Make
sure to remove the safety before removing or unloading the
mainspring housing. The thumb safety is removed by cocking the
hammer, and pulling upward on the safety while turning it clockwise.
Once freed, the slide stop plunger assembly may pop out, so be
careful to track fast moving small parts. The long pin on the thumb
safety, the safety pivot pin, retains the safety and the grip
safety. The grip safety will come back out of position, but it will
not fall out of the frame as it is also being retained my the gun's
mainspring housing.
The grip safety should be removed to allow viewing
the new thumb safety sear lug from the back of the frame when it is
being fitted. The mainspring housing must be lowered from its
installed position to clear the lower locating tab on the grip
safety. It is good to keep in mind the mainspring housing in under
load from the mainspring when disassembling. The mainspring pin is
pushed out left to right; cupped side to the left. Once the housing
is lowered and the grip safety is removed, the housing is pushed
back into position and retained with a punch of a size similar to
the pin.
This is a shot of the original thumb safety in place
in the frame and some rather sloppy file work from when I reworked
it to clear the new sear that was installed during the last segment.
The sear lug serves two purposes; it has a shoulder recess that
locates it to the frame so it doesn't fall out and, when rotated to
the "on" position with the hammer back, it blocks rearward movement
of the sear. Rotated to the "off" position, there is sufficient
clearance for the sear to rotate rearward and release the hammer.
Whenever a trigger job has been done, or any of the
related parts have been changed, it is important to ops check the
thumb safety to make sure it is doing more than filling the holes in
the side of the frame. It is possible for a thumb safety to fit the
frame holes and rotate normally, including detent lock up, without
restraining the sear when it is positioned to do so. That sounds a
little Shakespearian.
As received, new thumb safety sear lugs are not cut
for clearance. They are oversize to permit fitting to a specific
gun. You can see the notch in the lug on the right hand safety
above, the original. When an attempt is made to insert the new
safety, it bumps into the sear and cannot be fully installed. The
safety's sear lug must be notched the depth of the interference and
for a length consistent with the space under the safety as indicated
by the double arrow.
With the safety flipped over on its back. I cut a
0.059" notch in the flat that faced the sear. This is not a place
for a Dremel as too much off means throwing the piece away and
starting over. I used an 8" smooth mill file and held the part in my
hand when removing material. I would make about 3 or 4 cuts, then
install the safety and try it for clearance. The idea is not to
progress so much on each cutting cycle, that an overrun by that increment would
destroy the safety.
It is possible to install the safety and over-rotate
it so that the file cut will not be square to the sear when engaged.
The easiest way to avert this problem is to install the slide and
rack it back into position to the safety "V" notch in the slide.
This will keep the safety correctly positioned. The cut should be
uniform and as parallel to the lug axis as possible, which is
another reason to use a larger file. Going at it with a needle or
Swiss file or a Dremel would tend to make for an irregular surface.
I also keep a can of compressed air on the bench so I
can blow off metal filings before trying the part for fit. This way
I don't have to worry about loose metal particles getting into the
trigger mechanism and I don't have to listen to a compressor filling
its tank.
The safety lock detent on the Ed Brown piece was
perfect as received, locking into on or off positions with a
positive snap. If the locking is too heavy, the edge of the detent
can be hit with a Dremel polishing wheel; fixing the problem and
giving you justification for the $26,000 master Dremel kit that's
sitting on your bench. If the detent is too shallow, Brownells can
supply you with a detent spotting hand drill, 492-002-000, that
makes deepening the detent recess an easy deal for less than $25.
Pictured left is the finished fit. The safety
has enough clearance so it won't drag on the side of the sear, but
close enough on sear back surface contact to ensure it will not move
when the safety is on. There really is very little latitude for slop
in the fit. In this case the sear / hammer engagement is only a little over
0.020". That doesn't leave much to work with in keeping the safety
close to the sear.
Reassembly
Reassembly of the gun is pretty much the
reverse of disassembly already covered above, including slide
alignments and hammer cocked position as required. It is good to
have at least one thumb nail to facilitate working on the 1911, the
one that compresses the safety lock plunger when twisting the thumb
safety back into position.
Is it worth the time and effort?
 From a functional standpoint, the upgraded piece
makes the gun safer and more positive in use. It also facilitates
a better shooting hold. From a monetary perspective, a gunsmith
charges between $70 and $120 to install a thumb safety, depending on
the shop and the parts being installed. This is a low buck build up.
As far as intangibles go, there is a lot of satisfaction is
accomplishing this work correctly on your own gun. The tools
required are minimal and simple hand tools, so the biggest
ingredient is patience.
Throughout the process I've referenced Brownells. For
anyone attempting this type of work for the first time, or for
anyone who is attempting more complex projects, beyond the seemingly
endless supply of parts and variations of parts Brownell technical
support is invaluable. If you have questions about part selection,
application or installation, you can give them a call or email and
you'll get a complete and accurate response. That experience can
save a lot of time, money and aggravation and it is a resource there
for the asking.
Next
I believe my next step is to upgrade sights. I'd like
to do this without slide replacement of cutting a front dovetail.
We'll see...
Building a Low Buck
Shooter - Part I
Building a Low Buck Shooter -
Part II
Building a Low Buck Shooter -
Part III
Thanks,
Joe |
