20 Gage Dilemma

[oldgranddad]

I recently purchased a 1937 vintage 20 gauge autoloading shotgun. It takes 2 3/4" shells. On researching barrel markings I found that it was designed for black powder. Modern target cartridges develop about 9,800-12,000 PSI for a 7/8 oz load.
Anybody know what range of pressures the black powder would have developed or where I might find that info? Bottom line is I really don't want to blow anything up.....especially me.
Thanks

 

[AJ]

I recently purchased a 1937 vintage 20 gauge autoloading shotgun. It takes 2 3/4" shells. On researching barrel markings I found that it was designed for black powder. Modern target cartridges develop about 9,800-12,000 PSI for a 7/8 oz load.
Anybody know what range of pressures the black powder would have developed or where I might find that info? Bottom line is I really don't want to blow anything up.....especially me.
Thanks

Who made the shotgun? Could help in answering your question.

 

[oldgranddad]

It's a Remington Sportsman sometimes called a model 11. Built on the Browning A5 patent.

 

[s&wchad]

I’m not aware of any manufacturer making auto loading 20 Gauge shotguns designed for black powder… especially 2-3/4” and as late as 1937. If it’s a foreign gun, it should have proofs that designate the type of propellant. If it’s US made, no way it’s for black powder.

How about telling us the make and model. Some photos, including the marking would definitely help.

Edit to add:
I now see it’s a Remington Sportsman. That was made for smokeless powder and is just fine for any modern 2-3/4” load, except for steel shot. Steel shot can damage the barrel.

 

[oldgranddad]

s&wchad, the barrel on this shotgun has this line of stampings on the left side ending near the receiver: 20 GA. BF IMP CYL X
According to the Remington Owners forum, the B=January, the F=1937, IMP CYL=improved cylinder and the X= Black Powder.
Maybe I made a mistake. I posted this here as an ammo question because joining the Remington Owner's Group is a PIA and I'm much more comfortable on this forum. Thanks for your input.

 

[s&wchad]

Someone misunderstood…

Remington used a code for the year and month. I don’t know the year codes by memory, but the months are determined by the keyword “BLACKPOWDERX”.

Note that the keyword contains 12 letters.
B = January
L = February
A = March
C = April
K = May
P = June
…
X = You guessed it, December!

 

[oldgranddad]

I thank everyone for their input. I have my answer.

 

[nicky4968]

It is an Auto 5 without a magazine cutoff. A superb bird gun.

 

[DWalt]

Some earlier 20 gauge shotguns were chambered for 2-1/2" shells, but I believe by 1937, they were all 2-3/4". There is no danger in firing 2-3/4" shells in a gun chambered for 2-1/2", so long as the slightly longer fired shells will clear the ejection port.

 

[Nevada Ed]

If you hunt upland game or dove, you have a sweetheart of a shotgun for the field.

Nice find and enjoy it.

 

[AJ]

Some earlier 20 gauge shotguns were chambered for 2-1/2" shells, but I believe by 1937, they were all 2-3/4". There is no danger in firing 2-3/4" shells in a gun chambered for 2-1/2", so long as the slightly longer fired shells will clear the ejection port.

I have a Winchester Model 12 in 12 ga. made in 1918. The chamber is for a 2 9/16 " shell. In the mid 20's they went to a 2 3/4" shell (as we have now). I have shot 2 3/4' shells in mine, but you have to bump the butt on the ground to get them to extract. Now I keep a couple of boxes of 2 9/16" shells on hand for it.

 

[s&wchad]

It’s not a good idea to shoot over length shells in short chamber guns, even if they eject.

The listed length of shotgun shell is measured with the crimp open. If you measure a modern 2-3/4” 12 gauge shell, you’ll see that it’s closer to 2-1/2 inches in length. The chamber is cut to allow the crimp to fully open, without entering the forcing cone.

If the crimp opens into the forcing cone, you’re basically swaging the shotcup and shot through the end of the hull. While most barrels are pretty thick near the chamber, pressure and recoil are increased. People do get away with it, but it’s not advisable.

A friend of mine had a lovely single trigger 16 gauge L. C. Smith with short chambers. He put a couple boxes of 2-3/4” shells through it and cracked the stock through the wrist.

 

[Skeet 028]

I have a Winchester Model 12 in 12 ga. made in 1918. The chamber is for a 2 9/16 " shell. In the mid 20's they went to a 2 3/4" shell (as we have now). I have shot 2 3/4' shells in mine, but you have to bump the butt on the ground to get them to extract. Now I keep a couple of boxes of 2 9/16" shells on hand for it.

Don't know about the 2 9/16 in 12 ga(have never seen a 12 in that length) 16s yeah. I happen to have a 1st year 12 ga (1915) and it is 2 3/4 inch. I also have a 1914 20 ga that was 2 1/2 inch but was re-chambered to 2 3/4 I also have a 1st year vent rib trap 12 ga(1919 or 20)...it is also 2 3/4 inch. 2 9/16 inch 16s were made until the 1950s...esp Browning A-5s. When I was working on guns I converted quite a few in the 70s. It was not hard to do

 

[AJ]

It’s not a good idea to shoot over length shells in short chamber guns, even if they eject.

The listed length of shotgun shell is measured with the crimp open. If you measure a modern 2-3/4” 12 gauge shell, you’ll see that it’s closer to 2-1/2 inches in length. The chamber is cut to allow the crimp to fully open, without entering the forcing cone.

If the crimp opens into the forcing cone, you’re basically swaging the shotcup and shot through the end of the hull. While most barrels are pretty thick near the chamber, pressure and recoil are increased. People do get away with it, but it’s not advisable.

A friend of mine had a lovely single trigger 16 gauge L. C. Smith with short chambers. He put a couple boxes of 2-3/4” shells through it and cracked the stock through the wrist.

When I bought the Model 12 the fact that the chambers were 2 9/16" never crossed my beady little mind. When I said something to a friend who is a gunsmith, he asked what year and then told me it was 2 9/16". He said we can ream the chamber as a lot of them had that done to them.

 

[Rpg]

It’s not a good idea to shoot over length shells in short chamber guns, even if they eject.

The listed length of shotgun shell is measured with the crimp open. If you measure a modern 2-3/4” 12 gauge shell, you’ll see that it’s closer to 2-1/2 inches in length. The chamber is cut to allow the crimp to fully open, without entering the forcing cone.

If the crimp opens into the forcing cone, you’re basically swaging the shotcup and shot through the end of the hull. While most barrels are pretty thick near the chamber, pressure and recoil are increased. People do get away with it, but it’s not advisable.

A friend of mine had a lovely single trigger 16 gauge L. C. Smith with short chambers. He put a couple boxes of 2-3/4” shells through it and cracked the stock through the wrist.

Sherman Bell did an in-depth study of theses issues (published in Doublegun Journal) and demonstrated that 2 3/4” shells in 2 1/2” chambers aren’t contraindicated. The only issue may be ejection problems necessitating opening the ejection port.

Although the issues identified by s&wchad are commonly recited in reference to shotgun cartridge length, the empirical evidence demonstrates that these beliefs are unfounded.

 

[oldgranddad]

I confirmed the 2 3/4" chamber before purchase. Since then, I have determined that it reliably loads and ejects high brass and low brass and aluminum Winchester cartridges.
As noted, it is the A5 without the magazine cutoff. It also seems to me that it doesn't have the bulk of the A5, especially in the forearm and stock. And since it only holds 2 in the magazine it's not as heavy when loaded. I'm really looking forward to some field time.
Thanks for the comments.

 

[smoothshooter]

I’m not aware of any manufacturer making auto loading 20 Gauge shotguns designed for black powder… especially 2-3/4” and as late as 1937. If it’s a foreign gun, it should have proofs that designate the type of propellant. If it’s US made, no way it’s for black powder.

How about telling us the make and model. Some photos, including the marking would definitely help.

Edit to add:
I now see it’s a Remington Sportsman. That was made for smokeless powder and is just fine for any modern 2-3/4” load, except for steel shot. Steel shot can damage the barrel.

I doubt that the gun is only safe for black powder, especially one made at that point in time.

 

[Skeet 028]

If it is a Rem 11 20 ga made in the 30s it IS a 2 3/4 inch chamber... shooting 2 3/4 in 2 1/2 chambers really only increases pressure a bit and recoil somewhat more. But some feel recoil different than others.. Only 2 shells in the mag tube means it is a sportsman 11. It may have bit differently shaped fore end than a regular Rem 11.

As for the M-12...is the ga 12 and is the length of the chamber marked on the gun? If not is is almost definitely a 2 3/4 inch chambered bbl. Without going to the vault to check I am pretty certain they had chamber length on them. The 20 ga 2 1/2 inch I have is so marked in front of the loading gate on the bottom

 

[DWalt]

Regarding firing 2-3/4" shells in a 2-1/2" 20 gauge chamber, I have it direct from the Winchester head ballistician (this was back around the 1999-2002 period when I was working with Winchester on some ammunition development projects for the USAF) that there is no significant increase in peak chamber pressure as a result. And if one thinks about it, there is no reason for that to happen. My question was occasioned as the result of my having a first-year production Winchester Model 1912 (later becoming the Model 12) pump shotgun in 20 gauge with a 2-1/2" chamber. As a side note, all early production of the Model 1912 was in 20 gauge, not 16 or 12 gauges. I have never had any issues in firing 2-3/4" shells in it - EXCEPT that Federal empties are too long to eject due to the shorter length of the ejection port, and are very difficult to remove. But Remington and Winchester plastic cases do not have that problem as they are slightly shorter than Federal cases. So I simply do not use Federal 20 gauge shells. Back in my youth, in the days of paper cased shells, I had a good friend who owned an elderly 12 Gauge LeFever double gun with 2-3/4" chambers. He always used 3" shells in it, and nothing bad ever happened. Of course with a double gun, there is no ejection port length problem.

"The 20 ga 2 1/2 inch I have is so marked in front of the loading gate on the bottom"

My early Model 1912 has no chamber length stamped anywhere on it. But at that time, it was made only in a 2-1/2" chambering, so there was no need to.

 

[2152hq]

The Winchester M12 in 12ga was a 2 3/4" chamber from the start.
..or the first few in production in 1914 were actually 2 5/8", then they were 2 3/4".
Depends on who wants to argue.

But,,Winchester didn't mark the chamber length on 12ga M12 till the 3" chambering came out in the mid 1930's.
Then they marked both the 2 3/4" and the 3" 12ga M12 chamberings to avoid 3" shells being placed in 2 3/4" chambered guns..
The unfired 3" shell will drop right into a 2 3/4" chamber.

I believe the short chambered 20 and 16ga M12 were also standardized to the 2 3/4" chamber length at about the same time.


Long shells in short chambers,,there's way too many variables to blanketly say that there won't be any problem in shooting or conversions to do so.
Each bbl and each shell or reload holds a long list of things that can be changed to make the outcome different from the previous firing.

Most of the time nothing happens as far as the shooter is concerned.
Sometimes not.
Some guns can be safely converted, some cannot. It takes some careful measuring of the bbl wall thickness to see how much can be safely removed for the extra chamber AND forcing cone lengths.
The latter will be much greater in length than the old style generally. Usually thought to be a plus for pressure reduction , but it's also done by much more metal removal from the bbl walls.
A lot of things to consider.

I've had more than a few shotguns of the SxS variety brought to me for an inspection. Only to find that chambers had been lengthened along with forcing cones to a point where the bbl wall thickess was very thin right in front of the chambers where the work had been done.
I have advised more than one owner not to fire a particular shotgun because of that. They go away unhappy sometimes mad, but I'm only being up front with them.

The tools and reamers needed to do such 'work' are easy to buy and pretty easy to use as well. Makes a quick buck for many a 'smith but the before inspection and some thought about the whole job and what you are going to end up with at times isn't there.

The other one you find quite often is the lengthening of M12 chambers.
The work would be done by simply reaming the chamber out on the bbl to the depth of 2 3/4".
Seems perfectly correct...
But the mechanic either doesn't or forgot to figure in the chamber ring inside the frame that is part of the O/A chamber length.
Now add 1/4" to the depth they just reamed the new chamber to..
the customer now has a 3" chambered gun. Plus a new long modern forcing cone as well.
I see this as well on 12ga Model 97's. They were 2 3/4" from the start of production anyway. No need to recut them to 2 3/4 obviously.
But if you just measure the chamber in the bbl assembly, like the M12, it will show a short chamber. You have to figure the Chamber Ring length into it as well.

Making it go bang is the easy part.