doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com 3" 20 ga in 2 3/4" chambers

We have all read and seen the data, research, experiences and discussions on firing 12 ga 2 3/4" shells in short(er) chambers. My question is what about the 3" twenty in 2 3/4" chambers. Any data or research on that? I know it is done as I had a friend in the 60's doing it. I am guessing any potential problems would be magnified due to the twenty's higher working pressure and smaller bore??

The SAAMI pressure standard of 12,000 psi applies to both the 2 3/4" and 3" 20ga. So other than the increase in pressure that would result from an overly long shell, pressure is probably not the main issue. But you'd be subjecting the gun (and yourself) to significantly greater recoil because of the heavier shot charge. Here's a comparison:

2 3/4" 1 oz, 1300 fps: 19.9 ft-lbs
3", 1 1/4 oz, 1300 fps: 31.1 ft-lbs

So right around 50% more recoil, assuming similar velocity.

Out hunting one day with the family members. We were at a steel only site. SIL ran out of ammo for his 1980 Citori 20 2 3/4". Borrowed shells from his son who was shooting a 391 3". Fired 4 3" steel loads in his Citori before he realized they were 3"; no damage.

The increased recoil is felt with three-inch 20 for sure. I use standard for grouse and three-inch for waterfowl. In the blind the difference isn't noticeable because of the mixing---that is, not being pre-disposed to flinch---and extra clothing undoubtedly helps. I don't use steel so can't speak of their higher velocities.

The Browning over unders of that era that I have seen were marked both 2 3/4" and 3". This is a new observation for me.

The Browning Superposed 20 gauge SuperLight(Super Light Weight) introduced in the 1960's was only chambered for 2&3/4" shells and so marked.
In any event it is not a good idea to shoot a shotgun shell in a shotgun not chambered for that specific shell.
Before the advent of steel, I shot a lot of 3" 20 shells at both pheasants and ducks. The difference between a 3" 20 and 2&3/4" Field load was quite noticeable, 2&3/4" 20 Magnum, not quite so dramatic but noticeable. -Dick

Why would anyone want to do this ?

There comes a time when a light gun is very appealing. I have fine 12s and a hammer 16 but more and more the gun in my 81st year is 20ga SKB o/u Model 500 IC/M for grouse, ducks and geese---waterfowling always from a blind. Gunning hereabouts sometimes involves a lot of walking in challenging terrain and I've found the results from a 20ga as very satisfactory. It's all friends and the dog anyway. I never try for a limit. Why bother? There are always birds around.

I think the question "Why would anyone want to do this?" was not directed at you, King, but towards the original poster who asked about using a 3" shell in a 2 3/4" chamber, btdst. You can usually determine this by looking at who the poster is replying to, inside the yellow highlighted block above the text.

This topic is not about using 3" shells in 3" 20 ga. chambers, it's about using 3" shells in 20 ga. 2 3/4" chambers.

SRH

Thanks for that, Stan. There sure is a difference between standard 2 3/4 and 3!