doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com 16 Gauge Length

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.....