20 ga. Chamber length

[Heff]

I have been reading through post with the search engine on various chamber lengths and gauges. Based on what I have been reading, the consensus seems to be that chambers were roughly 1/8" shorter than the desired shell to help seal pressures with the old fiber wads (2 5/8 for 2 3/4 and 2 7/8 for 3" in 12 ga)
Does this mean a 20 ga intended to shoot 2 1/2" shells would have 2 3/8" chambers? If so, can 2 3/4" shells be safely used in this configuration or should 2 1/2" be used?
I recently purchased a 20 ga made in 1911 that by my measurements with a machinist scale check out to be 2 3/8" chamber length to the front of the forcing cone.

[Robert Brooks]

A lot of 20 gauges Foxes did indeed have 2 3/8 inch chambers i have fires a lot of field 2 3/4 inch shells in mine until I started buying 2 1/2 inch shells.Bobby

[Drew Hause]

Chad: I had a 1924 20g Trojan with 2 3/8" chambers, and foolishly tried 2 3/4" 7/8 oz. skeet loads. Recoil was brutal, and if I'd been smarter would have checked the end of the shells for feathering caused by entering the forcing cones

67mm shell left - 65mm right



Please don't lengthen the chambers; end of the chamber wall thickness may be inadequate

[Dean Romig]

I've had that same experience, especially with a 20 gauge VH.





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[Heff]

Thanks guys, I ordered a flat of various 2 1/2" shells from RST yesterday.

[Bruce Day]

RST cartridges are fine but so are Remingtons, Winchesters, and Federals. I have Parker 20s ranging from A to D grades in both Damascus and fluid steel and that’s what I use.

[Dean Romig]

Bruce, can you buy 2 1/2" shells in those brands?





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[Southpaw]

I swear its crazy and confusing. These guns are marked 2 1/2 inch chamber and 2 3/4 chamber but aren't. Its like going to a lumber yard and buying a 2 by 4. Even that is not actually a 2 by 4. Rounding I just guess is the American Way.

[Dean Romig]

I asked the previous question because I have fired 2 3/4" shells in various 20 ga. Parkers, knowing that doing so would probably do no immediate harm to the gun but they smacked me hard enough to know I didn't want to shoot them in other than a hunting situation and never at clays. But I have to wonder, if they clobbered me that hard what effect would they have on the gun over time??





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[Kensal Rise]

More than one factor effects the felt recoil of a gun. Chamber length is one of them. In relation to the cartridge length, of course. If the mouth of a case restricts the passage of the charge into the forcing cone and barrel proper, it will contribute to felt recoil. But not by much.

Other factors include the LOADING. Which, in the case of most commercial ammunition is fairly "stiff." Each firm has its own idea of a good 20-bore load.

Gun weight is another factor. So is stock configuration. Buttstock "plate" or pad. Shooting style, etc.

However, I've fired thousands upon thousands of handloaded 3/4 oz. 20-bore loads in 2 3/4-inch cases/2 1/2 -inch chambers with perfect comfort and results. But that's just me...