I discovered a surprise this evening. A couple of months ago, I bought a German 16 gauge by H. Burgsmuller Gewehrfabrik Kreiesen. From the name, I placed the date between 1876 and 1905. The proof marks place it as pre 1894.

The gun is Belgian proofed, has a steel fore end assembly with both a side swing action lever and a side swing fore end release.

Everything appears normal except a set of Brownell chamber gauges shows the chamber to be a 2-1/4" chamber (exactly). The bores are marked 16.8mm (.663) and they measure exactly that. No choke (and none indicated). The chamber gauges fit precisely in the chamber. The gun just seems to have 2-1/4" chambersd. I have never seen or heard of that (although there were several proprietary brass shell chambers in different lengths). Would that be the answer? I assume the chamber would be a 60mm in Europe.

Does it have forcing cones or does it have a sharp step where chamber i.d. steps down to bore i.d. ?

Might have been made/chambered specifically for brass cases if you discover a sharp step.

I know that the Belgian's produced Aluminium 12 bore case cartridges and some are quite short and around the 2 inch mark. At the time there were quite a few cautionary remarks in the shooting press warning against using them in English 2 inch chamber guns. I have a number of these Aluminium cartridges in my collection. Gun could have been specifically made for these. Some 16's and 24 bore cases I have are also shorter than 2 1/2". Lagopus.....

It has a pretty abrupt step like a several of the Parker's I own from the 1870 to 1882 period. That, and an 1874 Sauer Cape gun with a rifle barrel in 20ga x 50 mm is what made me think it might be a brass chambering. I was just surprised that a shot barrel ws chambered for a 2-1/4" cartridge. I was wondering if a 2-1/4" shotshell was ever marketed.

I have never seen any 2 1/4” 16 shells or even a slightly similar metric equivalent. It was not uncommon for chambers to be kept short to give a better, quicker seal of the fiber wads. I suspect that is what you have. Question becomes to shorten hulls to 2 1/4”- 2 1/2” or alter forcing cones to relieve the short chambers/sharp forcing cone issue. I’d try 2 1/2” loads as it is and see if the top of the hull gets torn up. If so you will need to slightly alter the forcing cones. But you might find everything works well as it is right now.

I had a couple of fascinating discussions with Tom Armbrust a few years ago about an 1891 16ga hammer double that I’d “discovered” had chambers shorter than 2 1\2”. “Had he ever come across such?” Even though the discussion was long his answer was short, “No.” And he suggested that I have the chambers cast. After doing that I called him back to report the results. He said, “Wait. Let me guess. The chambers have a step.” “How’d you know?” It seems he’d previously had a fellow from Europe make the same “discovery” and in the end they found his gun also had a step. Turns out my gun does have 2 9/16” chambers but with a step at 2 7/16”. We talked about several possible “whys”, some of which have already been mentioned above, but in the end had to be satisfied with accepting that we couldn’t be exactly sure why.

most paper shotshells and plastic as well, are measured 1/4" shorter than fired length. So a 2 1/2" shell unfired is 2 1/4

From researching the origin of center-break pinfires for the Reilly history, I came across arguments in the UK press from the 1850's at the very beginning of break-action guns in UK, on the use of a squared off shoulder at the end of the Chamber. Apparently this was the way Lefaucheaux made his guns and this was copied. The first UK-made commercially marketed center-break gun was of course by Lang in Jan 1854 and apparently he copied Lefaucheaux and used the squared off shoulder. Later, he and others tapered it. It appears the squared off shoulder was European and it looks iike it remained in use in Europe long after the chambers had begun to be tapered in UK.

Here are two letters in "The Field" from 1858 dealing with the issue:

02 January 1858, "The Field." Letter in which the author discusses Lang using the shoulder in his original center-break guns (1st one appeared in January 1854), then later switching to tapering the shoulder:



09 January 1858, "The Field." Reply by Lang (in his usual snotty way), in which he said he always ground off the shoulder (which makes you think he was getting his barrels from Belgium). This is gainsaid by the editor of "The Field."

Collath had a short chambered shot cartridge number 6 or 4 that was a 16ga but short according to what I have read in the past.

Sometimes German Chambers are cut tighter. I owned a16ga German Gun marked at building with 70mm chambers, yet I discovered that they were cut tighter than my Belgian marked 70mm chambers. So much so brass RMC hulls fire formed to the Belgian gun through repeated use could barely slip half way into the German gun. Yet the German gun was clearly marked 70mm.

It maybe the gun built for earlier fiber wads is more narrowly chambered and it is likely 65mm or if marked 70mm.

Nobel's "Unique" and Lancaster "Pygmies" short shells
https://books.google.com/books?id=inQCAAAAYAAJ&pg=PA339

On the next page are illustrations of several chamber/cone variants; No. 1 with the step or "square" cone, and mention of 2" cases by Joyce

One thing that I found with using my brownells chamber gages is when I measured a couple of my German Guns they measured short do to a taper in the chamber. try measuring with a micrometer or make a chamber gage out of a wood dowel and sand a slight taper on the front half.of the dowel

AGS,
You didn't show proof marks but said it was proofed, so I'm guessing it has a 16 in a circle on each barrel. This mark is for the standard 65mm chamber. A gun with any other chamber has to be marked with the length of the non-standard (as example 70 for 70mm, etc.) chamber. This mark is placed by the proof house after the "view proof"(mark-crown U), which included verification of dimensions. This means the chamber measured 65mm, within whatever tolerance was allowed. It is possible a modern gauge is larger in diameter, at the end, than the Proof Houses gauge. Gun makers, like anyone else, were conscious of their costs and often reground their chamber reamers as many times as possible and still pass proof. I don't know that this is the case with your gun, it is just a possibility.
Mike

Mike (& AGS), this was Tom’s strongest suspicion on my earlier mentioned gun. Frugality dictated regrinding the reamers as many times as possible and still stay within whatever limits that particular maker set.

The gun may just be on the small side of the spec. End of chamber diameter spec for a 16ga is .742 to .732. The end of my Brownells plug gage is .735. When chamber reamers got dull they sharpened them each sharpening made them smaller. Check the chamber length with a barrel wall thickness gauge. The indicator will change direction at the end of the chamber. My 12ga Brownells plug told me an LC Smith had 2in chambers. BWT showed it to be 2 3/4in

Collection of Aluminum shells courtesy of Lagopus

Well, I tried every test mentioned. Measureing with a depth caliper simply didn't work. While the chamber looks like it is stepped, the caliper end rod never was able to catch on it. It is apparently a very short radius or cone. A bore gauge pushed in stopped suddenly at the step, and measured 0.731. My Brownell gauge also measures exactly .735 at the front (yes, we have a winner!). To confirm, I tried a Magtech brass case and a Cheddite 2-1/2 inch case. They both measured within .003-.004 of 2-1/2" and were new and unused. With the extractors retracted on dismounted barrels, they both pushed in easily until flush. The trouble appears to be tight chambers and bores.

I have a set of 28" inserts in 28 gauge I recieved on a Parker I bought which really didn't need them. They are a two diameter design and the front has been turned to fit the chokes and the two rear sections are supposed to fit inside the normal bore. The muzzle ends fit well but the steps on the barrel section are oversized by a few thousanths. I need to hone or bore the barrel slightly for some pits in the back half (barrel walls are very thick) and plan to take them down a few thousandth's until the inserts have a proper friction fit. I this doesn't take the barrels enough to cean them up, I will likely use the inserts and shoot light 28's in it. Closest I will likely ever get to buying a hammer 28.

Drew, thanks for posting the photo for me. The crimp closed aluminium 12 bore cartridges are 2 1/4" when fired and contain 1 1/8th. ounce of shot. The 16 and 24 bore ones are also 2 1/4". The 12 bore ones on the right are 2 1/2". I once owned a Belgian .410 shotgun with the chamber length marked on the Proof Marks as 63mm. which equates roughly to 2 1/4".

Some German made shotguns I have encountered have very sharp angled chambers and I can only think that it was done to accommodate a true 2 1/2" paper roll crimp case that when fired would give a seamless transition of the shot from cartridge to bore. 2 1/2" being 65mm. it is considered safe to fire a 67mm. cartridge in these guns but the sharp chambered German guns will chew off the end of the case a bit and leave it ragged looking. Lagopus.....