Chamber Length

[Vaughn Jones]

New to this. I bought a Parker 20 gauge O frame SN 165683 which I understand was built in 1913. I have been told to take it to a gunsmith to determine the chamber length and correct shell length, but don't have one in this area that gives me any confidence, or even one that I would trust to handle it. I fired a couple 2 3/4 inch light target loads through it and it kicked like a 16, but with the big drop at the heel, hard to tell.

I know you guys have dealt with this before. Anyone know if this is 2 3/4, 2 1/2 or something else?

Also, it has a dent that is barely visible about 10" from the muzzle on the full choke barrel. Could this become a problem?

[David Hamilton]

There are some inexpensive steel plugs that are made in various bores that you can put in your chamber and measure the length. I can't remember , but I think I got them from Lyman or Mid-Way. David

[Double Play]

Hi Vaughn,
It has been said that long shells in short chambers can increase recoil. Also as you indicated excessive DAH tends to hit you a little harder or so it seems. If you plan to shoot your gun much you may want to pick up some low pressure shells as it will increase your shooting pleaser and be gentler on the gun. I believe a smaller payload (3/4 oz/20 gage) in tightly chocked guns gives less recoil and better patterns.

[Dean Romig]

I agree with Larry completely. I have a 1928 VH 20 gauge that abuses me mercilessly if I use standard off the shelf ammo. It has 2 1/2" chambers and just doesn't like those shells at all. I will not even shoot that gun with anything but 2 1/2" RST 5/8 or 3/4 oz. loads.

[D. Shane Burton]

RST, website of company referenced by Dean Romig:

http://www.rstshells.com/

Shane

[Researcher]

Parker Bros. certainly didn't rush into making the chambers of their 20-gauge guns longer after Western Cartridge Co. introduced their 20-gauge Super-X shel in a 2 3/4 inch case in 1922. A year earlier Remington Arms Co., Inc. introduced their sleek little Model 17 pump gun for the 2 3/4 inch 20-gauge shell. I've got a 1930-vintage, VH-Grade, 26-inch barrel, 0-frame, 20-gauge and it is chambered for the old style 2 1/2 inch 20-gauge shell. With Parker Bros. policy of holding chambers 1/8 inch shorter than the intended shell, their guns actually have 2 3/8 inch chambers. Same with A.H. Fox Gun Co.

Chamber depth is considered to be the distance between the breech end of the barrels and the joint between the chamber body itself and the forcing cone, which reduces down to bore diameter. This is loosely based on the length of the "Fired" shell. Today, theoretically when the crimp opens on the shell being fired the end would land at the junction of the chamber and cone. Prior to WW-II many companies had the practice of holding the chamber about 1/8 inch shorter than the shell for which it was intended. Fly in the ointment is nominal measurements often differ from actual ones in both chambers and shells. A very good method I have found of measuring chambers without much outlay of cash, and is quite accurate enough for virtually any situation, is a common 6" flexible machinist's scale which you likely have. Hold the barrels with muzzles toward a light source, not necessarily a concentrated one a window is great, while looking into the breech and the cone will be thrown in a shadow. May have to move the barrels around a little until it is distinct. While still looking into the chamber simply slide the scale in until you observe the end coming flush with the shadow line & mark position of breech end with your thumb. Remove and read the scale. I usually repeat this a few times to insure I am getting a consistent reading, but you will be amazed how accurate this can be done. While I own a Galazan chamber gauge, I use this more often than not. The chamber body itself has a taper of about .005" per inch. Sometimes chambers were cut with slightly worn reamers giving a slight undersize chamber. If the chamber is a bit undersize a gauge made to "industry" standards will not go in to the true depth of the chamber. A.H. Fox Gun Co. shotguns are known for having tight chambers. The machinist’s scale method can be more accurate.

[Pa SxS]

I use the same method as Dave and it works great.

[Bruce Day]

I have 20ga Parkers from 1902, 1910 and 1927. I follow the Parker recommended loads for these guns of 3/4oz at 2 1/4DRE or max 7/8oz at 2 1/2DRE. ( from Parker brochure The Small Bore Shot Gun, p. 9) Works great.

If you have chosen a gun having significant DAH, the felt recoil will be greater. Most of those little upland 20's have about 2 1/2"DAH, mine do. If you have been shooting so called "light target loads" through it, you have been shooting the Parker recommended maximum load.

Now subjectively, I shoot the lighter loads at targets and the heavier loads at larger gamebirds.

FYI, Win AA's are 2 5/8" when fired. They work fine in a Parker 2 1/2" chambered 20ga, which was the standard Parker 20ga chamber for many years.

The barely visible dent you mention is cosmetic only.

[Austin W Hogan]

Bruce is exactly correct; note the modern AA 20 laying alongside the machinist's scale in the first photo; it measures 2 5/8 inches after being fired. More surprising is the Super X Twenty 1 1/8 ounce maximum load magnum on the opposite side of the scale. The 3.20 on the box is the price paid in Van Horne's Hardware in Fultonville NY in the late 1950's. I don't have a fired 2 magnum, but I have a fired Super X twenty ga 5 from the same place and time surviving in the box of fives. The Super X five measures 2 11/16 minus in the second photo.
Both of these boxes are labeled 2 3/4 Inch, and carry a stern warning not to fire these in guns with chambers shorter than the length on the label.
The third photo shows a 1930's (or perhaps 1940's) vintage Remington Kleanbore Shurshot. It measures 2 5/8 minus
I have only had two Remington Parkers in residence here. Both were traps, and both sets of chambers measured 2 3/4, although they may have been lengthened along the way.
We have heard the story of shells longer than the chamber sealing on the mouth many times. The only publication found to substantiate this was contributed by Ed Muderlak; around 1933, an industry professional fired 3 inch magnums in a 410, and found patterns improved over 2 1/2 shells, although 1/2 inch was burned off the case on each firing.
The Remington shop order to chamber Parkers "2 5/8 inches for 2 3/4 inch shells" is well known. Could it have been a typo intended to say "2 3/4 chambers for 2 5/8 shells? The SAAMI standard (2.75 - .100) seems to support this.

Let's renew the search for a pre 1934 citation of short chambering

Best, Austin

[Vaughn Jones]

I want to thank each of you for your advice. You have really been helpful and I am impressed with the depth of knowledge in this organization. I plan to try out some 2 1/2 inch shells and see if it is a more comfortable shoot. Will report back to you.

Best wishes,

Vaughn Jones