doublegunshop.com - home Forums Thread Like Summary - Fox Sterlingworth 20 Help

Merry Christmas, everyone!

A good friend of mine recently acquired a 20 gauge Fox Sterlingworth S/N 2657XX and has been experiencing intermittent issues with the RH barrel firing. Following a misfire, the shell in the RH barrel typically exhibits a "somewhat light" primer strike. The LH barrel is 100% reliable even when transferring the misfired shell from the RH barrel. Several different brands of shells have been tried with no clear patterns developing when it comes to shell brands/misfires.

The gun was taken to a local, reputable gunsmith early this past summer and had the hammer springs replaced. We were told the hammers/pins were measured and found to be within tolerance. Prior to returning the gun, the 'smith test fired the gun 30-40 times using 3 or 4 different brands of shells with no issues. Before returning the gun to its owner, I put a box of Winchester (white box) and a box of Challenger shells through it with no issues.

Yesterday, the owner of the gun had 3 or 4 RH barrel misfires using both Fiocchi and Challenger shells. I happened to be present and inspected the misfired shells. The primer strikes were somewhat light but not terribly light. All misfired shells fired just fine in the LH barrel.

It kind of seems like the RH firing pin might be .001-.002" short or something along those lines.

Any insight would be greatly appreciated.

Also, if anyone knows of a gunsmith specializing in Fox Sterlingworths in the NC/SC/GA region, please feel free to let us know.

Much thanks,

BC

Gunningbird;

I sent you a PM with my South Carolina location and email address.

Kindest Regards;
Stephen Howell

You can check for this condition by just taking the bbls off and looking down into the action at the cocking arms of the hammers.
They should be pretty much even when in the raised (cocked) position.
If one hammer arm is lower than the other, that hammer is not rotated back as far when 'cocked'.
Then you'll have to remove the trigger plate to see why it is so.

Could be a shortened sear nose, or an altered sear notch in the hammer itself.
Repairs or attempts to gain some sort of benefit in trigger pull can be the causes/need for the work having been done.

One other quick check,,Dry fire the right bbl with the bbls off.
Then very carefully check the protruding firing pin and see if the pin (which is a one piece solid part of the hammer) can be wiggled back and forth
at all. Or if it can be pushed back into the frame even a small amt.
There should not be any movement to the pin. They are not rebounding hammers.
It should be down hard against the frame under the coil main spring tension.
Even in the hammer down position, there is a lot of pre-load tension on those main springs.

If you can move it at all, that points to the mainspring, mainspring follower, or even the hammer being stalled at some point before the hammer reached full'down' position

Yep.

Shell rim thickness has a wide tolerance these days.

The euro shells are sometimes thin. Might be within ‘spec’ but still a problem.

I would try a few boxes of Federal shells. The rims are on the thick side and the primer has a rounded profile.

You might also try handloads in Remington shells with Cheddite primers. They have a thin primer cover and are the most sensitive of all of them.

The Fox mainsprings are very strong, that was not likely to be the issue.

Old guns just sometimes complain about our modern crummy ammunition.

Check the sear length. A sear that has been worked on in an attempt to lighten trigger pulls can become too short to hold the hammer back far enough to get a full swing. Take the bottom plate off and see if the right hammer is as far back as the left.