dwebb210
04-04-2004, 08:44 AM
I have posted before about my Sigarms Trailside not
functioning properly because the firing pin wasn't crushing
the rimfire shells enough to fire.
My theory was that the firing pin was too short.
Most other people felt I had a dirty gun causing the bullet
to not fully seat, and not allow for a solid firing pin strike.
I haven't had a chance to shoot it since I last posted.
Yesterday, I finally got out to the range. The gun was
squeeky clean. The barrel had been thoroughly scrubbed
and was shiny smooth. No trace of lead or powder fouling.
There was a misfire on the 6th shot.
I almost threw the gun in the air for use as skeet.
When I got home, I had a pocket full of bullets that had
tiny scuff marks where the firing pin had barely made contact.
I loaded them into a magazine, and started cycling the
gun. I couldn't see any trouble with feeding or chambering.
Then it struck me...
I removed the slide, and grabbed a new box of ammo.
One at a time, I dropped a bullet into the chamber.
Roughly half of them would drop down until the rim hit the
breech. The other half would stick up a little. Some of
these would easily seat with a light touch. Others required
significant force.
A dial micrometer quickly solved that question. Bullet
diameters were all over the place. 0.221 - 0.226.
I did some more measuring and determined that the
chamber must begin to taper just before the bullet engages
the rifling.
Since I was mad enough to take a torch to the gun, I didn't
think I had anything to lose. So I went out to the garage
and found a drill bit with a shank that would fit into the
chamber. The shank of the bit measured 0.228".
I ground the end of the shank to about a 30 degree angle.
I sanded the identification stamp marks down flush with
400 grit sandpaper.
I tested the bit's hardness compared to the gun, and to my
surprise the gun's metal was harder. I heated the bit
red-hot with a torch and water quinched. I polished it again
with 400 grit sandpaper,
The bit wasn't long enough for me to chuck in a drill, so I
found a small steel pipe that I could use as an extension.
Using Beartooth Bullets bullet lapping compound, I slid the
shank of the drill bit into the chamber, and lapped for
about 10 seconds at full drill speed.
I switched to 15 micron diamond polishing compound,
then 6 micron, then 1 micron, then 0.25 micron.
The chamber is mirror smooth again.
Now only about a quarter of the bullets don't fall to the rim
when dropped into the chamber. But they are easily seated
with a light touch.
A trip to the range proved it worked.
Now instead of a misfire every 10 rounds or less,
I got three misfires out of 150 rounds.
And these were due to bad shells. Not due to lack of
firing pin dent.
It could be that using match grade target ammo with more
consistent bullet diameters would have solved the problem.
However, who wants a gun so tempermental. Not me.
In my opinion, this was something I should have left to
a professional gunsmith. But like I said, I was so mad I
didn't care.
I am VERY impressed with the precision to which this gun
was made. But the tight tolerances caused me more
problems than the gun was worth.
Problem solved.
I think I'll keep it now.
Dave
functioning properly because the firing pin wasn't crushing
the rimfire shells enough to fire.
My theory was that the firing pin was too short.
Most other people felt I had a dirty gun causing the bullet
to not fully seat, and not allow for a solid firing pin strike.
I haven't had a chance to shoot it since I last posted.
Yesterday, I finally got out to the range. The gun was
squeeky clean. The barrel had been thoroughly scrubbed
and was shiny smooth. No trace of lead or powder fouling.
There was a misfire on the 6th shot.
I almost threw the gun in the air for use as skeet.
When I got home, I had a pocket full of bullets that had
tiny scuff marks where the firing pin had barely made contact.
I loaded them into a magazine, and started cycling the
gun. I couldn't see any trouble with feeding or chambering.
Then it struck me...
I removed the slide, and grabbed a new box of ammo.
One at a time, I dropped a bullet into the chamber.
Roughly half of them would drop down until the rim hit the
breech. The other half would stick up a little. Some of
these would easily seat with a light touch. Others required
significant force.
A dial micrometer quickly solved that question. Bullet
diameters were all over the place. 0.221 - 0.226.
I did some more measuring and determined that the
chamber must begin to taper just before the bullet engages
the rifling.
Since I was mad enough to take a torch to the gun, I didn't
think I had anything to lose. So I went out to the garage
and found a drill bit with a shank that would fit into the
chamber. The shank of the bit measured 0.228".
I ground the end of the shank to about a 30 degree angle.
I sanded the identification stamp marks down flush with
400 grit sandpaper.
I tested the bit's hardness compared to the gun, and to my
surprise the gun's metal was harder. I heated the bit
red-hot with a torch and water quinched. I polished it again
with 400 grit sandpaper,
The bit wasn't long enough for me to chuck in a drill, so I
found a small steel pipe that I could use as an extension.
Using Beartooth Bullets bullet lapping compound, I slid the
shank of the drill bit into the chamber, and lapped for
about 10 seconds at full drill speed.
I switched to 15 micron diamond polishing compound,
then 6 micron, then 1 micron, then 0.25 micron.
The chamber is mirror smooth again.
Now only about a quarter of the bullets don't fall to the rim
when dropped into the chamber. But they are easily seated
with a light touch.
A trip to the range proved it worked.
Now instead of a misfire every 10 rounds or less,
I got three misfires out of 150 rounds.
And these were due to bad shells. Not due to lack of
firing pin dent.
It could be that using match grade target ammo with more
consistent bullet diameters would have solved the problem.
However, who wants a gun so tempermental. Not me.
In my opinion, this was something I should have left to
a professional gunsmith. But like I said, I was so mad I
didn't care.
I am VERY impressed with the precision to which this gun
was made. But the tight tolerances caused me more
problems than the gun was worth.
Problem solved.
I think I'll keep it now.
Dave