What Causes Doubling?

[Bill Jacobs]

What might cause a Trojan 12 ga to double fire?

Bill Jacobs

[Brian Dudley]

Dirty action. A wear sear spring. Hammer sear or notch wear.

[Dean Romig]

Whatever it turns out to be, if by disassembling and cleaning the action, it continues to double, it needs to go to a gunsmith experienced in classic sxs’s.





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[Aaron Beck]

Ill admit that I have occasionally experienced this and it was the operator. Gloves, heavy loads, poor gun mount or whatever and your finger can just brush back. Bamm.

[Billy Gross]

I have had an experience with a loose gun mount on a K-80. The butt bonces off my shoulder effectively causing a second pull. Both barrels go off almost simultaneously. Technically that is not doubling. Billy

[Stan Hillis]

Very doubtful that his Trojan has a single trigger. Involuntary (secondary) pull doesn't happen with double triggers. If it does though, there's a chance that could be causing it. With double triggers, it's dirty, or has a mechanical issue, almost certainly, as per Brian.

[Bill Jacobs]

I disassembled and cleaned the gun thoroughly. Did not see any mechanical damage. When I reassembled it and test fired it, I could not get it to double with RST shells. I am not sure what ammunition the owner was using in it. He could have easily used 2 3/4 inch shells. This gun has short chambers and should use 2 1/2 inchers. I will let him know that.

Bill Jacobs

[Mike Koneski]

I doubt that gun was chambered for 2 1/2" 12g shells. Probably for 2 5/8". If so there should be no issue shooting 2 3/4" target loads through that gun. Someone may have tinkered with the sears to lighten up the trigger pull? If so that could lead to an unsafe situation.

[Dave Noreen]

I have a Sterlingworth pin-gun that worked fine if I fired it right/left but would occasionally double when shooting the left barrel first. When the late Bill Harvey disassembled it there was a small splinter stuck on the right sear in old, congealed oil that kept the sear from fully engaging the notch. Gave the right barrel a nice light trigger pull. The stock also had an internal crack so I had him restock it with a piece of Claro I'd been hauling around with me for a couple of decades.

[Bill Jacobs]

These photos show my 12 gauge chamber gauge. The bottom line is at 2 9/16 exactly. The next photo shows the gauge inserted into the chamber. It is indeed 2 9/16. The RST shells are about 2 1/2 inches exactly. They are fine for these guns. I really don't like to see 2 3/4 inch shells used in them.

https://live.staticflickr.com/65535/52956186925_b84a53f52b_z.jpg (https://flic.kr/p/2oFyipB)Chamber Gauge (https://flic.kr/p/2oFyipB) by jakefromclemson (https://www.flickr.com/photos/24542443@N04/), on Flickr

https://live.staticflickr.com/65535/52956256508_ec76ce8be8_z.jpg (https://flic.kr/p/2oFyE6j)Chamber on Trojan (https://flic.kr/p/2oFyE6j) by jakefromclemson (https://www.flickr.com/photos/24542443@N04/), on Flickr

[J. Scott Hanes]

Where can one purchase a chamber gauge? A good, accurate, one.

[Dean Romig]

Do you simply want to measure depth or ID as well?





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[Dave Noreen]

The problem with all chamber gauges is that they are made to present day industry specs, while the chambers of many, if not most, vintage doubles were not. Using a machinist scale is often much more accurate.

[Bill Jacobs]

When I was in gunsmithing school, I made the gauge in the photos along with .410, 28, 20 16 and 10 gauge models. We made them (as I recall) 0.005 inches less in diameter than the minimum SAAMI chamber spec. I have not yet run into a chamber that I couldn't use them in.

Bill Jacobs

[allen newell]

Brownell, connecticut shotgun among others have chamber gauges for sale.