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Recent experiences while
using a Stoeger Coach Gun has forced a somewhat deeper understanding of
the inner workings of the action. After a year of use the Coach Gun was
getting harder and harder to open after firing, sometimes requiring
cracking over the knee. Some have suggested that the factory firing pins
on the Stoeger Coach Gun are 'soft' and mushroom, others say that the
Stoeger Coach Gun has a habit of having the firing pins stick in the
fired primer.
Both suggestions are somewhat correct and related. The factory firing
pins are softer than the should be and the pin doesn't really stick into
the fired shotshell primer. After removing the firing pins, the hammer
end was found to be bulged by as much as 0.006"; not enough to prevent
slipping the firing pin into its position but enough to cause it to
stick in position after shooting. The bulged portion of the pin made the
firing pin stick in the receiver hole, in the fired position, and that
could be described by some as sticking into the shotshell primer. The
firing pin end (end that hits the shotshell primer) were found without
defect. The damage is at the other end where the hammer strikes.
Examining how the firing pins fit into the receiver shows that the
hammer end (fatter end) slips through a hole and the pin end slips
through a hole in the retaining cup. A small spring (do not loose it!!)
fits between the underside of the retainer cup and a flange on the
firing pin. This spring forces the firing pin rearward when the coach
gun is cocked. Not having any replacement firing pins forced a 'battle
of the bulge' to correct the situation. The base dimension of the fatter
end was found to be 0.150" and one pin was oversized by 0.006" and the
other was oversized by 0.003". The bulges were found at the very end of
the pin where the hammer strikes. If anyone has hammered away at a brass
tool long enough you will recognize what has happened. Correcting the
bulges involved chucking the pin into a hand drill (a machine shop lathe
would also work, but didn't have one available in the house). The drill
chuck will easily hold the forward end of the pin. Attempts to hold the
portable drill with one hand and attempt to employ a file to the bulge
did not work that well. Better success was to press the bulged pin
against a common knife sharpening stone. Move the pin back and forth to
prevent gouging a deep hole into the sharpening stone. Measure the pin
diameter frequently; once you reach the same diameter of the pin base
dimension stop! A slight chamfer at the end of the pin should also help
slow down future bulging. This fix only took a few minutes per pin and
was easy. |
