July
S M T W T F S
1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31
Who's Online Now
8 members (ithaca1, canvasback, 1916XE, Jtplumb, eightbore, 1 invisible), 94 guests, and 5 robots.
Key: Admin, Global Mod, Mod
Forum Statistics
Forums10
Topics37,050
Posts519,665
Members14,183
Most Online462
Aug 5th, 2016
Previous Thread
Next Thread
Print Thread
Page 2 of 3 1 2 3
Joined: Jan 2002
Posts: 8,871
Likes: 142
Sidelock
**
Offline
Sidelock
**

Joined: Jan 2002
Posts: 8,871
Likes: 142
Originally Posted by L. Brown
According to the information I have, what used to be called double proof is now called triple proof, with the proofmark repeated 3 times. If your gun dates from the 30's, then that's not 11,000 kilos . . . but still a very stout proof at 18,000 psi. The Robust is more or less the Stevens 311 of France in terms of numbers produced . . . but much higher quality. Very solid guns. "Robust" is a well-chosen name.

No proof house marks on that one, Larry. Manufrance was allowed to proof their own firearms at a few points in history. A few of the French guys have posted that it was equivalent to proof at the official proof house, but, I don’t know the numbers. The exact, same gun will sometimes be seen with the word “Costo” on it, instead of “Robust”. Same gun. Same manufacturer.

Best,
Ted

Joined: Mar 2005
Posts: 10
dbh1956 Offline OP
Boxlock
OP Offline
Boxlock

Joined: Mar 2005
Posts: 10
Do the two "palm fronds" next to "Acier Hercule" mean double proof? I've seen pictures of three palm fronds on Darne before. What does 1100 kilos stand for? im curious because I know of a 20G "French" SxS at a LGS that I will look at next week. Ive got 65mm 16's on hand but a 65mm 20 gauge is a different situation and I would probably want to get it lengthened.

Joined: Jan 2006
Posts: 8,597
Likes: 78
Sidelock
***
Offline
Sidelock
***

Joined: Jan 2006
Posts: 8,597
Likes: 78
A proof pressure of 1100 kg/cm2 = 15,646 psi, for a service load pressure of about 10,000 psi
The pressure numbers were however obtained using lead crushers, and pressure derived by modern piezo transducers would be 10-14% higher.

I would be very cautious about lengthening the chambers of a light weight continental 20g, and then only by an expert like Dean Harris at Skeets Gun Shop
Tahlequah, OK
918-456-4749

Joined: Jan 2002
Posts: 8,719
Likes: 44
Sidelock
*
Offline
Sidelock
*

Joined: Jan 2002
Posts: 8,719
Likes: 44
regarding lengthening the chambers...why the vague caution? either there is enough metal there or not...i like .090 in front of chambers...what say you?


advocating doublegon happiness...via 90/30 guidelines...
Joined: Jan 2002
Posts: 8,871
Likes: 142
Sidelock
**
Offline
Sidelock
**

Joined: Jan 2002
Posts: 8,871
Likes: 142
Originally Posted by Drew Hause
A proof pressure of 1100 kg/cm2 = 15,646 psi, for a service load pressure of about 10,000 psi
The pressure numbers were however obtained using lead crushers, and pressure derived by modern piezo transducers would be 10-14% higher.

I would be very cautious about lengthening the chambers of a light weight continental 20g, and then only by an expert like Dean Harris at Skeets Gun Shop
Tahlequah, OK
918-456-4749

The OPs gun is a 16 Drew, not a 20.

The further I get down the road of life, the more French guns I see. What I haven’t seen on that road is a FRENCH gun, with FRENCH proof that suffers from thin walls. Quite the opposite, typically.

They might be out there. But, they ain’t running around in bunches.

The rest of the stuff, off the continent, I have no clue.


Best,
Ted

Joined: Apr 2018
Posts: 192
Likes: 11
Sidelock
Offline
Sidelock

Joined: Apr 2018
Posts: 192
Likes: 11
Originally Posted by dbh1956
Do the two "palm fronds" next to "Acier Hercule" mean double proof? I've seen pictures of three palm fronds on Darne before. What does 1100 kilos stand for? im curious because I know of a 20G "French" SxS at a LGS that I will look at next week. Ive got 65mm 16's on hand but a 65mm 20 gauge is a different situation and I would probably want to get it lengthened.

the two fronds on the barrel flats are not proof marks...they are in-house MF quality marks. most of the french makers utilize a similar marking system that denotes the quality of the gun...poincons on darnes, rabbits/swallows, etc....any symbol that is repeated is likely to be makers quality marks. this gun has only single proof marks...they are repeated on the barrel flats and the water table....the arrow through the bullseye target attended by the PT is the standard MF proof...PT is the post 1900 smokeless powder used in the proofing process. it may be shown one, two, or three times, thus indicating the level of proof.


but as doc drew shows (and ted attests to) the standard (single mark) french proof is a substantial test, and will provide a gun able to tolerate any reasonable load intended for a gun of the weight of these hunter's guns.

best regards,

tom


"it's a poor sort of memory that only works backwards."
lewis carroll, Alice in Wonderland
Joined: Jan 2002
Posts: 11,081
Likes: 20
Sidelock
**
Offline
Sidelock
**

Joined: Jan 2002
Posts: 11,081
Likes: 20
I would not bother lengthening the chambers. It's easy enough to work up light 3/4 oz target loads using standard American 2 3/4" hulls. Pressures will be well below that of a gun that has passed French proof. If you're planning on hunting with the gun, I'd just buy 2 1/2" RST's for that, or else something like the Gamebore British 2 1/2" loads.

Joined: Oct 2009
Posts: 6,084
Likes: 89
Sidelock
***
Online Content
Sidelock
***

Joined: Oct 2009
Posts: 6,084
Likes: 89
Originally Posted by Ted Schefelbein
Originally Posted by Drew Hause
A proof pressure of 1100 kg/cm2 = 15,646 psi, for a service load pressure of about 10,000 psi
The pressure numbers were however obtained using lead crushers, and pressure derived by modern piezo transducers would be 10-14% higher.

I would be very cautious about lengthening the chambers of a light weight continental 20g, and then only by an expert like Dean Harris at Skeets Gun Shop
Tahlequah, OK
918-456-4749

The OPs gun is a 16 Drew, not a 20.

The further I get down the road of life, the more French guns I see. What I haven’t seen on that road is a FRENCH gun, with FRENCH proof that suffers from thin walls. Quite the opposite, typically.

They might be out there. But, they ain’t running around in bunches.

The rest of the stuff, off the continent, I have no clue.


Best,
Ted

While I don't have the experience Ted does, the dozen or so Manufrance Ideals that I have owned or handled ALL had barrels that would more than handle any load you wanted to fire off in a gun of that weight. Didn't matter if they showed single, double or triple proofs.


The world cries out for such: he is needed & needed badly- the man who can carry a message to Garcia
Joined: Jan 2006
Posts: 8,597
Likes: 78
Sidelock
***
Offline
Sidelock
***

Joined: Jan 2006
Posts: 8,597
Likes: 78
In reference to this
I know of a 20G "French" SxS at a LGS that I will look at next week. Ive got 65mm 16's on hand but a 65mm 20 gauge is a different situation and I would probably want to get it lengthened.

I only have end-of-chamber wall thickness for one French gun
1950s Verney Carron 12b., 2 5/8" chambers: 0.100"

For interest - 4 Francottes
Francotte (1938) 12b., 2 5/8" chambers: 0.098"
Francotte (1894-5) 12b., 2.5" chambers: 0.085"
Francotte (1896) 12b., 2.5" chambers: 0.085"
Francotte (1930) 20b., 2.5" chambers: 0.095"

Possibly those with experience with French guns could share the end-of-chamber numbers

Joined: Mar 2005
Posts: 10
dbh1956 Offline OP
Boxlock
OP Offline
Boxlock

Joined: Mar 2005
Posts: 10
Sorry I muddied the water with mention of another different shotgun. I looked at it today. A 20 gauge Helice. I will post about it separately. I did not buy it but took some photos. I hate dark gunshops! Trying to edit the photos now.

Last edited by dbh1956; 05/23/22 08:48 PM. Reason: misspelled shop
Page 2 of 3 1 2 3

Link Copied to Clipboard

doublegunshop.com home | Welcome | Sponsors & Advertisers | DoubleGun Rack | Doublegun Book Rack

Order or request info | Other Useful Information

Updated every minute of everyday!


Copyright (c) 1993 - 2022 doublegunshop.com. All rights reserved. doublegunshop.com - Bloomfield, NY 14469. USA These materials are provided by doublegunshop.com as a service to its customers and may be used for informational purposes only. doublegunshop.com assumes no responsibility for errors or omissions in these materials. THESE MATERIALS ARE PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANT-ABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. doublegunshop.com further does not warrant the accuracy or completeness of the information, text, graphics, links or other items contained within these materials. doublegunshop.com shall not be liable for any special, indirect, incidental, or consequential damages, including without limitation, lost revenues or lost profits, which may result from the use of these materials. doublegunshop.com may make changes to these materials, or to the products described therein, at any time without notice. doublegunshop.com makes no commitment to update the information contained herein. This is a public un-moderated forum participate at your own risk.

Note: The posting of Copyrighted material on this forum is prohibited without prior written consent of the Copyright holder. For specifics on Copyright Law and restrictions refer to: http://www.copyright.gov/laws/ - doublegunshop.com will not monitor nor will they be held liable for copyright violations presented on the BBS which is an open and un-moderated public forum.

Powered by UBB.threads™ PHP Forum Software 7.7.5
(Release build 20201027)
Responsive Width:

PHP: 7.0.33-0+deb9u11+hw1 Page Time: 0.044s Queries: 35 (0.023s) Memory: 0.8526 MB (Peak: 1.8992 MB) Data Comp: Off Server Time: 2022-07-04 12:22:02 UTC
Valid HTML 5 and Valid CSS