Caravanman Posted August 7, 2015 Report Share Posted August 7, 2015 My new (old) Eibar has 70mm chambers and proofed to 850kg yet all my Gamebore 70mm shells are for 900kg proof. Any recommendations for a suitable cartridge? Quote Link to comment Share on other sites More sharing options...
scarecrow243 Posted August 8, 2015 Report Share Posted August 8, 2015 Hi some boxes of cartridges have the same pressure rating ie 900kg no matter the shot load Quote Link to comment Share on other sites More sharing options...
deershooter Posted August 8, 2015 Report Share Posted August 8, 2015 Shot load has nothing to do with pressure ,just because it's 34 gram doesn't mean it's higher pressure than 24 gram Quote Link to comment Share on other sites More sharing options...
wymberley Posted August 8, 2015 Report Share Posted August 8, 2015 My new (old) Eibar has 70mm chambers and proofed to 850kg yet all my Gamebore 70mm shells are for 900kg proof. Any recommendations for a suitable cartridge? Are you sure that the 900 figure is in kgs? Quote Link to comment Share on other sites More sharing options...
scarecrow243 Posted August 8, 2015 Report Share Posted August 8, 2015 900kg or 3 tons is the limit for 2 3/4 - 70mm magnum on eley cartridges 850kg is for standard cartridges makers put higher kg etc to cover them selfs Quote Link to comment Share on other sites More sharing options...
wymberley Posted August 8, 2015 Report Share Posted August 8, 2015 900kg or 3 tons is the limit for 2 3/4 - 70mm magnum on eley cartridges 850kg is for standard cartridges makers put higher kg etc to cover them selfs Are you sure about that post? Quote Link to comment Share on other sites More sharing options...
scarecrow243 Posted August 8, 2015 Report Share Posted August 8, 2015 if you have a box of eley 2 3/4 magnum lead catridges they tell you that the proof pressure is 900kg or 3 1/2 tons 3 inch is 1000kg or 4tons some guns are marked in bars ie 850 bars etc every gun proof tested are tested at a higher pressure than the gun is marked for as every cartridge dose not give constant pressure due to powder.temp etc etc Quote Link to comment Share on other sites More sharing options...
ChrisAsh Posted August 8, 2015 Report Share Posted August 8, 2015 So if his gun blows up you are happy for him to claim damages off you if that advice is wrong, as you are 100 percent you are correct I would advise you use the cartridges that meet the proof house stamp Quote Link to comment Share on other sites More sharing options...
scarecrow243 Posted August 8, 2015 Report Share Posted August 8, 2015 i am saying he should look at the boxes he has and look at the proof pressure ie if they have say 85okg for 24grm load and 850kg for a 36 gram load its a standard printing on the boxes Quote Link to comment Share on other sites More sharing options...
wymberley Posted August 8, 2015 Report Share Posted August 8, 2015 The problem is we're talking 20th Century and the OP has not given the load. The standard 2 3/4" (70mm) service pressure was 3 1/4 tons. The Spanish, as stated above, did proof many 70mm guns at 900 kg/sqcm and this permitted the use of 1 1/2"oz and, again, as indicated, permitted the use of the 2 3/4" Eley Magnum which probably accounted for more wildfowl than any other cartridge for 12 bore users. Consequently, if the OP's cartridges (which are obviously somewhat dated) are annotated as requiring a proof load of 900kgs, then he might like to think twice before using them in a gun proofed at 850. With regard to the current situation, he can use any cartridge annotated 12-70. Quote Link to comment Share on other sites More sharing options...
Gunman Posted August 8, 2015 Report Share Posted August 8, 2015 As there have been many changes to proof pressures and the way they are both measured and tested ,even those of in the trade get confused . An email to the proof house or cartridge loader stating the proof marks and date of proof might help . Quote Link to comment Share on other sites More sharing options...
Paul T Posted August 8, 2015 Report Share Posted August 8, 2015 I had a concern a while back when some one handed me some 'mini-magnum' cartridges on a fox drive and it got me thinking about my older guns and which cartridges I could safely shoot. To extract from my post last year... "I then phoned Lyalvale Express who put me onto a very knowledgeable chap who explained the whole thing on pressures and velocity (for 2 1/2"). Legally they are not allowed to manufacture and sell a cartridge which exceeds 700bar pressure and a 2 1/2" chambered gun is proofed for 850bar (3 tons). The majority of their cartridges are in the range of 500-600bar typically - Lyalvale have a 2" 25g cartridge at 530bar and a 42g 2 3/4" at 600bar and the pressure is moderated by using different powders. So the rule of thumb would be if the guns are nitro proofed and the chamber is correct, then it will be fine." I am GUESSING (the key word) that similar will apply for 2 3/4" cartridges and the legal pressure limit will be a long way below the 900kg, so at 850kg proof marks your gun SHOULD (another key word!) be fine with any 70mm cartridge. If you want to use Gamebore cartridges I'd just give them a call and ask what the relative figures are - explain why and you should be given a definite answer. Do post back up here as I'd be interested to know... Quote Link to comment Share on other sites More sharing options...
Caravanman Posted August 9, 2015 Author Report Share Posted August 9, 2015 Thanks for the replies. The cartridges arnt old, they are Velocity 29g 6. Quote Link to comment Share on other sites More sharing options...
wymberley Posted August 9, 2015 Report Share Posted August 9, 2015 Thanks for the replies. The cartridges arnt old, they are Velocity 29g 6. Hi, Just purely out of interest now - does the box give a range of different proof limits or just the kg/sqcm? I only ask as that rating is now obsolete and one would have expected something in Bar or even MPA as, as I wrongly thought, they're not dated but current. Cheers Quote Link to comment Share on other sites More sharing options...
Caravanman Posted August 9, 2015 Author Report Share Posted August 9, 2015 Quote Link to comment Share on other sites More sharing options...
wymberley Posted August 9, 2015 Report Share Posted August 9, 2015 Many thanks for taking the trouble to do that. They've cleverly covered all of the more modern various proof stages. Of the various options detailed, the (70mm) is the one you'll be interested in I think you'll find. Quote Link to comment Share on other sites More sharing options...
matone Posted August 10, 2015 Report Share Posted August 10, 2015 You could just use 2 1/2" ....67mm loads to be sure. Quote Link to comment Share on other sites More sharing options...
Caravanman Posted August 10, 2015 Author Report Share Posted August 10, 2015 Yes. Off out just now to get some. Quote Link to comment Share on other sites More sharing options...
Caravanman Posted August 10, 2015 Author Report Share Posted August 10, 2015 Just picked up a slab of Eley pigeon 65 mm Quote Link to comment Share on other sites More sharing options...
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