Taming the Jimenez JA-380
Trigger-Pull
Let's be frank. The trigger-pull on these guns
leaves a lot to be desired. As my brother once put
it "It would make a mule team sweat". But, it doesn't have to be
that way, and with a little work it can be much better.
Firing-pin
[click for larger image]
I'll start with the firing-pin. In the picture above,
the edge that I have pointed to with the red arrow needed to be rounded and
smoothed. I was careful not to round this too much, as the
idea is to make it easier for the sear to slip off but not for it to become
"dangerously" easy. The flat surface area that I have marked in
yellow also needed to be smoothed. The smoother these two areas are,
the smoother the trigger-pull will be. I used fine emery-cloth and a small
whet-stone on the firing-pin shown in the photo above.
An alternate method:
This is a replacement firing-pin, and it was extra
rough. It was so rough that it failed to yield to emery-cloth
or whet-stone.
[click for larger image]
So I put it into the jaws of an electric drill.
[click for larger image]
I used the tip of my little 440 knife blade as a lathe tool
to work it over. I had the drill rotating in the direction towards me, and
ran it about medium speed. It came out very well and was quite
quick. I will most likely use this method from now on.
As you can see, it did a really good job on both the
edge and on the flat surface too.
[click for larger image]
Sear
The sear was made with a sharp
pointed top edge, and the flat sear surface was very rough.
I nicely (and a bit aggressively) rounded the top edge, and smoothed the
flat contact surface area.
To do the work, I used the small whet-stone and
fine emery cloth. The sear is made of some pretty hard metal, so it takes
a little work. At the same time, I made sure to
slightly round-off all of the other sharp edges on the sear.
[click for larger image]
The rounding-off of the sharp sear point is very
important to how the trigger pulls at the end of the pull when the
firing-pin slips free from the sear. I wanted a nice clean break, not
too crisp, and not too soft. So, I took a bit off at a time until I got it
just right. It is important to note the importance of not rounding this
off too much. If rounded too much, the trigger-pull could become
dangerously short and dangerously easy.
[click for larger image]
This flat sear surface is the area that contacts
the flat surface on the firing-pin above. The two surfaces must slip past
one another for the firing-pin to be released. These two surfaces
must be smooth for a nice, consistent, and smooth trigger-pull. So, I
made sure to smooth this the best I could without removing too much
material.
The rest of the sear piston body needed work
too. In the picture below, the area that I have marked in light-green
needs to be smoothed, because this area has pressure against it while the
firing-pin is cocked. The edge that I have marked in yellow, needs to be
rounded so that it does not dig into the sides of the sear cylinder. And
the entire lower portion below the guide pin (marked with red) needs to be
well smoothed around the entire body.
[click for larger image]
If you look at the other two pictures of the
sear above this one, you can easily see where I have sanded it with emery
cloth.
Sear
Cylinder
All the edges of the cylinder opening needed to be
rounded and deburred. I have tried to show these in the picture below
with my red arrows.
[click for larger image]
The metal used for the body of these guns is a soft
Zink containing alloy. So it was easy to smooth and round all of these
edges with my little knife blade. I also used the hard tip of a small
jeweler's screwdriver to work the lower edges that were hard to reach with
my knife blade.
The cylinder walls needed to be smoothed and
polished.
[click for larger image]
For this job I used that same small jeweler's
screwdriver and that same little knife. I used the smooth rounded
sides of the screwdriver down in the lower portions of the cylinder, and I used
my small knife in the upper regions. I also inserted the sear, and
moved it up and down about a thousand times, while applying pressure to
different areas of the sides of the cylinder. All this polished and
smoothed the cylinder very well as you can see in the picture
above.
Trigger Cam
The trigger-cam needed a bit of finish work as
well.
[click for larger image]
The areas marked with red arrows needed to be
rounded and deburred, and my little knife worked well. But, for the areas
marked with light-green, I had to use the whet-stone and emery cloth. I
took my time and made sure that there would be no rough edges that would hang-up
on the side of the gun body.
[click for larger image]
The right side of the gun body, under the grip, and
under where the trigger transfer-bar and trigger-cam connect, needed to be
smoothed down to allow for free and easy movement. I just used the fine
emery cloth and lightly sanded the finish smooth (no need to worry about rusting
with this alloy).
Disclaimer
Please understand that there
are no guarantees or warranties, implied or otherwise, and that the reader
understands that no legal responsibility is held by the author for any
information that is written here. This site is intended for
entertainment purposes only. The author takes no responsibility for
anything that a reader might do, or for a reader's interpretation or
application of the information within. I am in no way associated or
affiliated with Jimenez Arms, and I do not represent them in any
manor.
All information and images © 2006 this website.
