Questions on chamber length

[Cory Rams]

So here’s something new after all these years. I just watched a YouTube video talking about a double gun and showing marks on it. Obviously there’s not enough marking on mine really tell me much. The YouTuber was talking about his 28 gauge that had a “28-70” stampeded on the receiver. He said the 70 was mm and the equivalent in inches was 2 3/4 inches for shells. Well, I have a number 65 stamped on my underside of my barrels which if I went by this logic it would tell me it’s closer to a 2.5” inch chamber and not a 2 7/8” chamber??? Back in the 90s. I had a gun Smith measure my chamber and told me it was 2 7/8” 10 gauge. I have shot RST shells 2 7/8” in it with no problems. Drops right into the chamber and shuts fine. Wondering if maybe somebody had it bored out to 2 7/8” or if there’s just enough free play in the chamber that they fit???? Does this make sense to anybody here that can chime in and tell me if that’s what the 65 stands for? Actually 65 mm is equivalent to 2.55906” so I’m guessing it is saying it’s a 2.5” chamber that’s been bored to 2 7/8” or has a lot of free bore? Just about all my hand loads are shorter since I roll crimp them with 2 7/8 and shells and cut them down. I would say most of my hand loads are 2 5/8 inch to 2 1/2 inch. The RST 2 7/8 inch factory loads fit just fine in there. I’ve shot in quite a few of them as well so I’m kind of confused now if that’s what the 65 really means. Like I said above, maybe bored it out or it has some free play?

[Drew Hause]

The gun does not appear to be a Parker.
6.5 would be the Ferlach proof mark for a 65 mm chamber
65 was used by the Belgian proof house (after 1892)
British chamber length would of course be in inches, until post-1989 and then metric.

Chamber length can be modified over the life of a gun, and the standard turn-of-the-century U.S. 10g shell was 2 7/8" (after firing).

There is an easy way to measure chamber length using a 3" x 5" index card, rolled lengthwise, and slid into the chamber. It will partially unroll and expand to the chamber diameter.
Gently advance the card until it stops at the end of the chamber (where the forcing cone constriction starts), use a pencil to mark the card at the breech end of the barrel, and repeat the steps to see if it always comes to same spot.
Then use a ruler to measure the length marked on the card.
The chamber must be clean, and it works best with a new 3” X 5” card.

Let us know what you find.

[Cory Rams]

Yep, thanks for the heads up. I’ll have to try that. I would assume it’s been bored out over its life to 2 7/8”. It’s a Charles daily stamped gun with not a lot of markings on anywhere. Did a post on it here years ago and I was told that the Deeley fore end release lever had a patent from 1873 so they figured it was somewhere in that neighborhood for production.

[Drew Hause]

Very old thread but Ken Georgi lists the hammer guns in the 1885 SD&G catalog
https://www.shotgunworld.com/threads...-double.27815/

https://www.doublegunshop.com/forums...&Number=586962

[6pt-Sika]

Originally Posted by Drew Hause

Very old thread but Ken Georgi lists the hammer guns in the 1885 SD&G catalog
https://www.shotgunworld.com/threads...-double.27815/

https://www.doublegunshop.com/forums...&Number=586962

Ken Georgi is a good guy ! He was in our group that went to Córdoba in February and I may see him in the morning at Prospect Hall

[Cory Rams]

One of those posts up above is my gun I believe. Drew, thanks for getting me on the ball and having me measure the chamber length finally got to it today. It averaged 2.775”. It explains why the two and 7/8 inch RST shells never pattern worth the darn. The hulls were so long that they were folding over the forcing cones and I’m sure my shot cups and shot were getting beat up. At least it got me into reloading 10 gauge. When I started reloading and using a roll crimp all my shelves are at least a half inch or so shorter. Plenty of clearance when my hulls “un rolled” from firing. I loaded up for the other day that have to be long enough that they’re just gonna be almost even with the forcing cone or right in back of it. I’m sure they’ll be fine. I still have 3 boxes laying around of unforced 2 7/8” impossible to find 1 1/4 oz lead loads. Just opened them up. There’s total of 13 of #5’s and 6 of number 6’s. So basically one short of 2 boxes. I’d hate to tear apart just for the hulls. Might have to see if I can trade someone for 2 5/8 ounce or some hulls.


It sounds like 65 mm (2.55”) which is what my barrel is marked falls in between 2 1/2 inches and 2 5/8 inch (which is 2.625”) ammo? I’ve been trying to do some research and looking at old posts here it seems like most shoot 2 5/8” loaded RST ammo in their 65 mm chambers? I’ll just make sure to cut my hulls shorter than 2.775” which is chamber length to my forcing cone… just like I’ve already been doing for years.

[6pt-Sika]

I’ve had Parker’s in 10 , 16 and 28 that lettered with 2 7/8” chambers . There were plenty Parker 20’s that lettered 2 7/8” as well .

[Cory Rams]

My guess is I just have a generic old gun because I dosen't have squat on it for stamping or numbers. Just that number #65. Not really much on the receiver or anywhere else for stamping either other than a few numbers…”396” and “FR”… or “FB”. There is also the same stamping on of F…R,P, or? Is kinda worn off. My gun must be either super old or was generic from the dollar store back in the day….lol. either that or the guy that made them had sore fingers and didn’t like the stamp. I know Charles Daly was an importer. I wonder what manufacturer this came from that he rest stamped his name on it. Guessing it will always probably be a life mystery to me.

[6pt-Sika]

Started the shoot Saturday at Prospect Hall and Ken Georgi and I were on the same squad . He shot well ! I got over heated and only did two of the six events . I took my butt to the club house and cooled of in the air con .

[Cory Rams]

Sounds fun ….and hot! You’re definitely on the other side of the states from me because it’s been cool and rainy here.