20 gauge chamber length
 

I don't have any reference material on Parker guns so I'm hoping someone here would be kind enough to answer my question. I am looking at a 20 gauge Parker -- it has 2 1/2' chambers. Is there a specific time period that Parker switched to 2 3/4" chambers on their 20 gauge guns? If so is there also a serial number range that would indicate 2 1/2' vs 2 3/4"? Thanks, Ron

The Parker Story doesn't say when, but 2-1/2" was the standard 20ga chamber length at least until 1920.

It likely changed to 2 3/4" under Remington ownership - earlier, I'm sure, by special order.





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Thanks...

This is probably a dumb question but what exactly is a 2 1/2" chamber? Is the chamber exactly 2 1/2" long or is it chambered to fire 2 1/2" shells? I assume the latter -- so a 2 1/2" chamber is probably 2 3/4" long?

And as a followup, can a 2 1/2" chamber safely be lengthened to 2 3/4"? Pros and cons?

Chambers are measured from the breech surface of the barrels forward to the point where the taper of the forcing cone begins. If it measures 2.5” then you have 2 1/2” chambers.
On chambers with the tapered forcing cone, paper shells that open 1/8” longer than the chamber length were intended to be used. The extra 1/8” of shell length that opened into the cone was to provide a superior gas seal.

It is not advisable to lengthen the chambers on these old doubles. Not only do you destroy the value of the gun, unless wall thickness is very carefully measured, lenthhening chambers can compromise the integrity/safety of the barrels




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With Parker Bros. policy of holding chambers 1/8 inch shorter than the intended shell, many guns intended for the 2 1/2 inch 20-gauge shell actually have chambers about 2 3/8 inch to the forcing cone break. My 1930 vintage VH-Grade is so chambered.

From the 1890s onward, our North American ammunition companies offered paper 20-gauge NPEs and loaded shells in four lengths -- 2 1/2, 2 3/4, 2 7/8 and 3-inch. The "standard" 20-gauge shell was 2 1/2 inch and carried a maximum load of 2 1/4 drams of bulk smokeless powder or 18-grains of dense smokeless powder such as Infallible or Ballistite pushing 7/8 ounce of shot. Back in the day, our ammo companies didn't include the shell length on the box labels of "standard" length shells.

Attachment 74370

The 2 3/4 inch, and longer, shells could be had with a slightly hotter load of 2 1/2 drams of bulk smokeless powder or 20-grains of dense smokeless powder such as Infallible or Ballistite pushing the same 7/8 ounce of shot. The perceived advantage of the longer 2 7/8 and 3 inch shells was more/better wadding.


Attachment 74369

I have a 20 gauge built in 1916. The PGCA letter states the gun have 2 5/8" chambers.

Ken

How long are your barrels Ken?





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Dean,

The barrels are 28" and according to the letter the requested chokes were RH 40% and LH 60%.

Ken

My 1918 DHE 20 was ordered to have 2 5/8 inch chambers. It has 30 inch barrels and open chokes as specified in the order.

My 1900 VH #97948 letters with 2 5/8" chambers with 28" choked modified and "close".

Garry, a DHE 20 with 30" barrels and open chokes, would be a dream gun for me.
I have really come to like 30" open choke guns.

I have a 30-inch barrel, AE-Grade, 20-gauge, Ansley H. Fox that shipped in 1920 to B.H. Dyas Co. in Los Angles. The order card specified "chamber for 2 3/4 shell". The chambers are 2 5/8 inch.

Attachment 74381

Wow Dave, what a great gun. How is she choked?

It cards full and full and measures .031" in both barrels. I bought it 15 years ago from Wes Dillon when he was still running the Gun Library at the flagship store in Sidney. Truth be told I shot one round of trap with it as a function test and it has been a gunroom queen ever since.

Saw Wes at the Colorado Gun Collectors show in May. He is living in Colorado now.

Is Wes working for Morphy?





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I'll have to measure the chamber length in my ejector Sterlingworth 28" with .043" of choke in the left barrel.

I just checked - the chamber length is 2 5/8" which is correct for 2 3/4" shells.





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It's probably 2.5" Dean but in the meanwhile check out the thread "2.5 vs. 2.75in. on the Fox site. Scott Kittridge has done some interesting, but not surprising to me, pattern testing with a 20ga. Fox.

By the way Dean, do you have the bore dimensions and the constrictions for both barrels?

It's 2 5/8" Daryl. I edited my above post to reflect this.





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You have to wonder why they make it so confusing. A loaded 2 3/4" shell is actually 2 1/4" long -- if it's a folded crimp, after it's fired it measures just under 2 5/8"

So why are they called 2 3/4" shells?

What average joe hunter would think it's ok to fire 2 3/4" shells in a gun with a 2 5/8" chamber?

If the gun with 2 5/8" chambers had the chamber length marked on the barrel would it say 2 5/8" or 2 3/4"?

The first picture from left to right:

loaded 2 3/4" 28 ga, fired 2 3/4" 28 ga, loaded 2 3/4" 20 ga, loaded 3" 12 ga, loaded 2 3/4" 12 ga, fired 2 3/4" 12 gauge

Second picture:

fired 2 3/4" 20 ga measures 2.618" (just under 2 5/8")

Ron, not all shells of the same gauge are exactly the same length when fired.

“Average Joe hunter” needs to familiarize himself with chamber length and barrel wall thickness and the type of ammo he thinks he can use in these classic old doubles. If that’s too much trouble for him, he really has no business shooting classic old doubles.

A 2 5/8” chamber was made to shoot 2 3/4” shells. The shell when fired, would open about 1/8” into the forcing cone. The belief was that this would provide a better gas seal.

I also have 20 gauge Parkers with 2 3/8” chambers that were made to shoot 2 1/2” shells.

There is also a ‘stretch’ factor in plastic shells and none of the modern plastic shells were manufactured with the requirements of our classic old doubles.



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Apparently, the SAAMI meeting where it was "suggested" that our manufacturers begin marking the chamber length on their shotguns was in 1937, and we begin seeing such markings on 1938 or 39 guns. Some examples from Remington autoloaders, August 1935 --

Attachment 74398

May 1937 --

Attachment 74400

April 1943 --

Attachment 74399

What Dave said.
A.P. Curtis published an article in the March 1938 American Rifleman entitled “Advantages of Short Shotgun Chambers” (courtesy of Larry Brown):
SAAMI, assembled in serious conference on March 26, 1937, passed the following resolution: “That an appropriate warning label be placed on all boxes containing smokeless powder shells, cautioning the consumer against using them in short chambered guns and also in guns with Damascus barrels and guns not in first-class condition.” The motion was made and seconded by representatives of two powder companies.
That same conference also passed a resolution requiring: “That all guns be marked so that the consumer will be able to tell the chamber length, as for example by marking 2 3/4 inch chamber etc.”

Hunter Arms lengthened the 20 gauge chambers from 2 1/2" to 2 3/4" in 1936.

Dean -- if a 2 3/4" shell actually measures 2 1/4" (see my picture in post above) and when fired measure less than 2 5/8" (see second photo) how does it "open about 1/8" into the forcing cone?"

By my measurements the fired case doesn't even reach the forcing cone. So there is no way they could create a better gas seal. Maybe loaded roll crimp cartridges are longer than loaded folded crimp cartridges? I don't have any to measure.

Ron, you're missing one basic fact... These guns were built to the specifications of paper shotshell casings manufactured (cut) to specific lengths. All of the ammunition manufacturers (and there were far, far fewer then than there are today) adhered to specific measurements for paper shotshells.

We can't compare apples to oranges as in shotshells manufactured in the latter half of the 19th century and early 20th century and those manufactured today.

By the way, and please correct me if I'm wrong, the only shells in your picture of six that appear to be factory new are the two in the center.... the other four appear to be reloads.





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Here is something that has been posted before. Scroll to about page 15 or so. The rest of the reading is pretty cool, too!

https://docs.google.com/document/d/1...vwLYc-kGA/edit

I don't believe I'm missing the point -- I made that very point in my last sentence about roll crimped cartridges. I totally understand the difference between modern manufactured plastic hulls and the older paper shells.

Regardless of the material used, the cartridge has one length when loaded (roll crimp or folded) and a longer length after it has been fired. Although I read about the 1/8" into the forcing cone theory in the article Scott Chapman provided a link to interesting it doesn't make sense to me. The paper hull obviously has a certain thickness and if it is not allowed to open fully (because it is 1/8" into the forcing cone) the wad and shot column would get squeezed down to a smaller diameter before entering the bore. How can that possibly be a good thing? To me the ideal would be for the cartridge to open fully in the chamber allowing the wad and shot to enter the bore without any constriction. Obviously the chamber length can't be so long that gas can escape around the wad. The other factor is the chamber diameter and hull thickness -- I would think the prefect situation would be to have the inside diameter of the hull (after being expanded by the gas pressure) be the same as the bore diameter -- that way the wad and shot column could make a smooth transition from the hull into the bore -- a difficult task since hulls don't all have the same wall thickness.

Check out this illustration, esp (c) showing the expanding gasses escaping past the squeezed down wad and shot column (caused by the hull opening into the forcing cone):

Here is the source of the attachment above:

https://books.google.com/books?id=in...page&q&f=false

May we know the author of this work of compilation?
We see the names of a few of our PGCA friends so can we presume this was compiled by Dr. Drew Hause?





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The google document that I posted was previously posted by Drew Hause back in April of this year. He wrote:

"Major Sir Gerald Burrard, The Modern Shotgun, Volume II, “The Cartridge”, 1955 3rd Revised Edition, p. 154 in reference to modern “star” crimped paper cases
“For all practical purposes any increase in pressure due to the longer cartridge case really does not exist provided the correct powder and shot charges for a nominal 2 1/2 inch cartridge are used.”

Obviously this applies to 2 3/4" hulls in 2 5/8" 12g chambers.

A summary of Bell's and Armbrust's study “Long Shells in Short Chambers”, in “Finding Out for Myself” Part V, Double Gun Journal, Winter 2001 is about 1/3 down here
https://docs.google.com/document/d/1...vwLYc-kGA/edit

The pressure increase for one load was 1200 psi

OTOH: I had a 1924 20g Parker with chambers slightly longer than 2 3/8". Recoil with standard 2 3/4" 7/8 oz. skeet loads was severe, and the case mouths were feathered, evidence that the hull had entered the forcing cone."
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The long and the short of it is that these are shotguns, fired at low pressures, from thick barrels. It just doesn't matter how long the shells or the chambers are, as long as the shells are not overloaded, everything will be fine, the pheasants will be dead and the guns will not blow up. I think Dr. Drew and others have clarified that in past research.

Scott: please help us understand your question.

Scroll down about 1/3 here and there are several references to shell and chamber length
https://docs.google.com/document/d/1...vwLYc-kGA/edit

“Mr. Griffith on Shotgun Patterns”, 1897
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA234
Studied “Turnover” – case longer than the chamber in reference to vintage roll-crimped shells

Charles Askins “The Cone” Field & Stream, Nov. 1921
https://books.google.com/books?id=UP...J&pg=PA700&lpg
W.A. King for Parker Bros.
Referring to the cone, we ordinarily permit our shells to lap into it 1/8-inch, but as a matter of fact we have found that the majority of guns will shoot a better pattern with even more lap than this. In fact, we can secure extra good patterns by shooting extra long shells, permitting the lap to extent to the point where we begin to tear off the ends of the paper. At that point we do not seek to give more lap. In user’s hands we do not advocate the use of longer shells than those which give 1/8 lap.

Everything in the shotshell world changed when Remington introduced the ‘SP’ high density polyethylene compression formed hull with a separate base wad in 1960, followed by the polyethylene ‘Power Piston’ wad in 1966.
Winchester/Western introduced the Mark 5 polyethylene shot collar in 1961, followed by the one piece compression formed plastic hull for the Super-X in 1964 and AA Target shells in 1965.
The Federal Riefenhauser (straight wall) ribbed plastic shotshell was introduced in 1965.

Many modern 2 3/4" plastic hulls are indeed a bit shorter than 2 3/4" after firing; the box is still labeled 2 3/4".

http://pic20.picturetrail.com:80/VOL.../410136599.jpg

I think there are good reasons to not use 2 3/4" loads in a 20g with 2 3/8" chambers.
2 3/4" 12 g loads are of no concern in 2 5/8" chambers.

Dr. Drew: I didn't have a question. Dean asked me for the author of the google document. I had reposted your info from a April 2019 thread in order to provide insight as to the variations in length of fired modern 20 gauge plastic shotshells.

From my keeping up with the discussion on this forum and additional reading, it is my understanding that many learned students of turn of the century fine shotguns believe that 20 gauge guns with 2 3/8" chamber were made to shoot 2 1/2" shells and 2 5/8" chamber guns were made to shoot 2 3/4". However there is variation in the length modern plastic shotshells which can muddy the waters.

Some on this board report to regularly use 2 3/4" shells in guns that are not 2 5/8" chambered, while some will only use 2 1/2". Some argue that it is more about the pressures generated (specifically when talking about composite barrel) and the stress on the old wood.

My take home message is that the more valuable a gun is and perhaps the older (composite barrels +/- oil soaked wood) the more likely the owner is to shoot low pressure RST 2 1/2" shells. I feel that you can't go wrong with this option even with a shooter quality VH or Trojan.

There are some that use standard 2 3/4" ammo in fluid steel barrelled guns (with adequate wall thickness) and never look back. Including heavy pressure waterfowl loads.

It is all what you are comfortable with personally. If you are worried about whether a 2 3/4" shell is going to pattern poorly, produce too much recoil, etc. etc, go out and shoot it on a pattern board and find out. If you don't want to go to the trouble, spend a little extra and buy RST shells and don't worry about anything!

Another interesting thread on 20 gauge chamber length f I'm 2017. http://parkerguns.org/forums/showthr...&highlight=RST

Also, the last time someone asked RST the 2 3/4" loads were lower pressure than their 2 1/2" loads. http://parkerguns.org/forums/showthr...light=20+gauge

Ken

Dead on right. How many times has this same matter come up ? Over and over and somebody must feel that their gun is so infirm that it will blow up if the slightest miscalculation is made . Enough, enough.

Agreed Bruce and Bill - but we can choose to be responsible or we can choose to be irresponsible when it comes to what ammo we stuff into our various shotguns....

There are neophytes in the realm of old side-by-sides who join our ranks or come onto our various websites every day of the year and I think it borders on the irresponsible to indicate they can 'throw caution to the wind' and shoot anything they want in their recent acquisitions.

As for me, I will continue to advocate for caution.





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I'm with Dean. Since none of us can know the abuse to which our maybe 120 year old guns have been inflicted, it would seem prudent to use reasonable due diligence to at least establish that the chambers/barrels have not been modified, and to use loads ballistically equivalent to those for which the gun was originally designed.
Parker Bros. probably knew what they were doing, documented the load with which the gun was patterned on the hang tag, proved every gun, and built in a significant margin of safety.
It HAS been proven that the pressures generated by turn-of-the-century smokeless loads were quite similar to today's if at the same payload and fps

Though opinions were offered, the cause of this blow up, to my knowledge, was never established by a metallurgical failure analysis
http://www.doublegunshop.com/forums/...=491058&page=1

http://pic20.picturetrail.com:80/VOL.../413569864.jpg

A buddy was bidding against somebody's grandma at an auction in Liberty, Mo. on a Damascus barrel 16g Parker. Grandma won, and told him she wanted it for her grandson to use turkey hunting. She didn't believe him when he suggested that use with modern turkey loads would not be a good idea.

Since this is a very frequent question, maybe in the "Help" section at the top of the Forum a "PLEASE READ THIS BEFORE SHOOTING YOUR PARKER" post could be generated? The FAQs seem to be overlooked.

I just added "Please review the General Information "Is my shotgun safe to shoot?" FAQ before using your L.C. Smith or Hunter Arms Co. Fulton shotgun." to the header of the LCSCA Forum.

No wonder the neophyte is confused. In one place he finds Sherman Bell’s test results in the Winter 2001 DGJ article where he writes:

“With loads that are sensible in a light 2 1/2 inch gun, we see no dangerous pressure levels produced. I see no reason, related to safety, to modify an original 2 1/2 inch chambered gun to shoot 2 3/4 shells, if the 2 3/4 inch load you intend to use would develop pressure that is safe in that gun, when fired in a standard chamber.”


Then in another place he finds Larry Potterfield showing him how to lengthen the chamber of an antique Parker:

https://youtu.be/amBveFBnVgY