scubajohn Posted March 9, 2013 Report Share Posted March 9, 2013 As you im a newbie what difference does chamber sizes on shotguns make Quote Link to comment Share on other sites More sharing options...
la bala Posted March 9, 2013 Report Share Posted March 9, 2013 in old money, you wouldnt try to put a 3 inch cartridge in a chamber what is 2.75 inches Quote Link to comment Share on other sites More sharing options...
TIGHTCHOKE Posted March 9, 2013 Report Share Posted March 9, 2013 As you im a newbie what difference does chamber sizes on shotguns make It's the LENGTH that is IMPORTANT. Different lengths of cartridges will not fit in all 12 bore guns. Quote Link to comment Share on other sites More sharing options...
scubajohn Posted March 9, 2013 Author Report Share Posted March 9, 2013 AH yes but why, what the reason behind half an inch difference Quote Link to comment Share on other sites More sharing options...
Big Mat Posted March 9, 2013 Report Share Posted March 9, 2013 Get more shot of bigger sizes into the cartridges. Especially important with non toxic Quote Link to comment Share on other sites More sharing options...
scubajohn Posted March 9, 2013 Author Report Share Posted March 9, 2013 now i understand thanks mat id rather look silly on here than the club Quote Link to comment Share on other sites More sharing options...
Big Mat Posted March 9, 2013 Report Share Posted March 9, 2013 Its a sensible question. If you only shoot clays/normal small game then you're very unlikely to come across 3" and 3 1/2" cartridges! Quote Link to comment Share on other sites More sharing options...
shakari Posted March 9, 2013 Report Share Posted March 9, 2013 It actually goes deeper than that. The older guns had 2 1/2 inch chambers whereas more modern ones have 2 3/4 inch chambers..... You need to check proof marks etc but as a rule of thumb, an older gun with 2 1/2 inch chambers can usually take 2 3/4 inch shells IF (note the big IF) they're rolled crimp. Quote Link to comment Share on other sites More sharing options...
Gunnerbob Posted March 9, 2013 Report Share Posted March 9, 2013 now i understand thanks mat id rather look silly on here than the club No question is silly, we all need to ask sometimes, how will we know if we don't ask ? Quote Link to comment Share on other sites More sharing options...
Guest cookoff013 Posted March 9, 2013 Report Share Posted March 9, 2013 I fyou look at 12gauge barrel design you`d notice multiple things, such as the diameter of the chamber is about 0.800" and can be any size from 2" to 3.5". then there is a minute ridge, to feed into the forcing cone, the forcing cone reduces the chamber diamiter to the bore size, both the length and angle of the forcing cone in open to interpritation to the manufacturers. then this leeds us to the bore size, the bore is open to complete interpritation from the manufacturers to any diameter and shape. i say that because some new designed shotguns have minor reduced muzzels. so the chamber question is important. only the chamber dimentions are strict. the shells increased in size to accomidatet larger steel shot. Quote Link to comment Share on other sites More sharing options...
Frenchieboy Posted March 10, 2013 Report Share Posted March 10, 2013 To try to help the OP a little more maybe someone with a little more knowledge or a better way of putting things over could explain things a bit further. Lets say that we have a fixed choke shotgun that is chambered/proofed for 70mm cartridges. Would there be any difference in velicity etc between using say a 67mm cartridge loaded with 28g of 6 shot and a 70mm cartridge again loaded with 28g of 6 shot? i.e. Does that extra 3mm in cartridge length make any real difference. Quote Link to comment Share on other sites More sharing options...
kent Posted March 10, 2013 Report Share Posted March 10, 2013 To try to help the OP a little more maybe someone with a little more knowledge or a better way of putting things over could explain things a bit further. Lets say that we have a fixed choke shotgun that is chambered/proofed for 70mm cartridges. Would there be any difference in velicity etc between using say a 67mm cartridge loaded with 28g of 6 shot and a 70mm cartridge again loaded with 28g of 6 shot? i.e. Does that extra 3mm in cartridge length make any real difference. Its more a case of were the pressure is produced. Remember its the fired length we go off not the unfired length. Putting a real high pressure non toxic 2 3/4 shell through a 3" chamber is safer than through a 2 3/4" chamber if your gun isn't HP steel proof for this reason. However it is still not good practise though many of us do it, then again regardless of std of proof when the gun was new there are a few I have handled I wouldn't shoot anything through Quote Link to comment Share on other sites More sharing options...
Paul223 Posted March 10, 2013 Report Share Posted March 10, 2013 It actually goes deeper than that. The older guns had 2 1/2 inch chambers whereas more modern ones have 2 3/4 inch chambers..... You need to check proof marks etc but as a rule of thumb, an older gun with 2 1/2 inch chambers can usually take 2 3/4 inch shells IF (note the big IF) they're rolled crimp. No sorry thats rubbish, the fired length is the stated size, so a 70mm cartridge will be 70mm opened up after firing, so using a longer cartridge which will go into the chamber results in the case unravelling into the forcing cone causing an obstruction which in turn will increase chamber pressure. A case fired like this will usually have a feathered or ragged edge to it caused by the shot and wad squeezing through! To try to help the OP a little more maybe someone with a little more knowledge or a better way of putting things over could explain things a bit further. Lets say that we have a fixed choke shotgun that is chambered/proofed for 70mm cartridges. Would there be any difference in velocity etc between using say a 67mm cartridge loaded with 28g of 6 shot and a 70mm cartridge again loaded with 28g of 6 shot? i.e. Does that extra 3mm in cartridge length make any real difference. indeed, whilst some say the reason is for increased weight of shot I'd say not so, it's probably more to do with metrication and standardisation, at the end of the day manufacturers produce 65, 67, and 70mm all with the same varying pay loads of shot, there can be an advantage to using longer cases in the fact more sealing area of the wad, speed is a result of quantity and quallity of powder. Quote Link to comment Share on other sites More sharing options...
wymberley Posted March 10, 2013 Report Share Posted March 10, 2013 (edited) but as a rule of thumb, an older gun with 2 1/2 inch chambers can usually take 2 3/4 inch shells IF (note the big IF) they're rolled crimp. Not a good idea though as sooner or later the 'IF' will be forgotten. Personally, I'm not so sure as I've just checked some crimped and rolled closure cartridges of different sizes - 2", 21/2 and 23/4 and in each case in the unfired condition the crimped are shorter which suggests to me that when fired they'll all be to the chamber length. Edit: Paul 223, my apologies. I read the thread earlier, walked the dog and jumped back in without reading through it again. Have just now spotted your post. Edited March 10, 2013 by wymberley Quote Link to comment Share on other sites More sharing options...
shakari Posted March 10, 2013 Report Share Posted March 10, 2013 The reason I added the rider of caution was for the obvious reason but if you check with any ammo manufacturer etc they'll tell you it's perfectly safe to use 2 3/4 inch rolled shells in a 2 1/2 inch chambered gun. Quote Link to comment Share on other sites More sharing options...
Paul223 Posted March 10, 2013 Report Share Posted March 10, 2013 No sorry but that is bad advice, the crimp type makes no difference to the fired length, stick to the correct length or shorter, but never longer regardless of crimp Quote Link to comment Share on other sites More sharing options...
shakari Posted March 10, 2013 Report Share Posted March 10, 2013 (edited) It absolutely isn't bad advice. I was first told it by one of the directors of Eley many years ago & he had their tech dept confirm it in writing to me & they have since re-confirmed it to me twice more. IIRC the reason you can do so is the OAL of an unrolled, rolled case (if you know what I mean) is less that the OAL of a crimped case and the rolled case obviously has a disc in the end. The end of a crimped case touches the forcing cones when fired but the rolled case, being shorter, does not. I probably still have the letters somewhere but if I do, I don't know where as we moved continents not very long ago and we still haven't unpacked everything but if you doubt me, I suggest you contact Eley or other reputable manufacturer to have them confirm it. Alternatively, measure a fired rolled case against a fired crimped case (obviously of the same length case) & you'll see the latter is noticeably longer than the former. I have however emailed Eley and asked them to reconfirm. Edited March 10, 2013 by shakari Quote Link to comment Share on other sites More sharing options...
wymberley Posted March 10, 2013 Report Share Posted March 10, 2013 IIRC the reason you can do so is the OAL of an unrolled, rolled case (if you know what I mean) is less that the OAL of a crimped case and the rolled case obviously has a disc in the end. The end of a crimped case touches the forcing cones when fired but the rolled case, being shorter, does not. Sorry, bit confused as to what you mean, could you possibly reword it? Alternatively, measure a fired rolled case against a fired crimped case (obviously of the same length case) & you'll see the latter is noticeably longer than the former. Just done it - Eley - the length is identical Quote Link to comment Share on other sites More sharing options...
shakari Posted March 10, 2013 Report Share Posted March 10, 2013 (edited) I'd be interested to see a pic. I do know Eley have told me several times it's perfectly OK to do & I do know I've been doing it for some years in my old 12 gauges (1923 & 1934) without problems & have noted fired rolled cases come out whole & crimped (on the very odd occasion I've used 'em) come out with the ends slightly feathered. I'll also be interested to hear what Eley tell me this time. Edited March 10, 2013 by shakari Quote Link to comment Share on other sites More sharing options...
Dangerous Brian Posted March 11, 2013 Report Share Posted March 11, 2013 I'd be interested to see a pic. I do know Eley have told me several times it's perfectly OK to do & I do know I've been doing it for some years in my old 12 gauges (1923 & 1934) without problems & have noted fired rolled cases come out whole & crimped (on the very odd occasion I've used 'em) come out with the ends slightly feathered. I'll also be interested to hear what Eley tell me this time. I have seen printed on boxes containing 67mm crimped shells suitable for 2 1/2 inch chambers (which is 65mm in new money as I understand). I have never seen that statement on a box of 70mm shells nor would I expect to regardless of whether they are rolled or crimped. As already said before the case length is measured before it is closed, so it makes no differnce what crimp you use as the fired case will end up being (more or less) it's original length. The advantage of a roll crimp is you can get more shot in it for a given case length compared to the industry standard star crimp, all other components being equal. Would it be unacceptable in your opinion to fire a 70mm RTO finished case through your 2 1/2 inch chamber gun then reload that same case, finish it with a star crimp and fire it again? It sounds to me like the message might have got a bit mixed up somehwere along the way. Quote Link to comment Share on other sites More sharing options...
shakari Posted March 11, 2013 Report Share Posted March 11, 2013 (edited) The messages I've had Eley and other ammo manufacturers have always been extremely unequivocal as one would expect from an ammo manufacturer. My shotguns are fairly/very good quality and I'm extremely careful what I put through them and would always ask manufacturers advice and of course follow it...... but they have on several occasions told me I can use 2 3/4 rolled in my 2 1/2 inch chambers and as I've previously said, I've never had a 2 3/4 rolled case come out with any feathering whatsoever but on the odd occasion I've used 2 3/4 crimped, they have always come out with a little feathering in the end of the case. Eley haven't replied me yet but (assuming they do reply) I'll post it asap. I've also searched for their previous communications but can't find them I'm afraid...... but quite honestly, that doesn't surprise me as I have something in the region of 25 boxes of gear that still hasn't been unpacked....... I'm still looking for something like 200 x .500 Jeffery cartridge cases and about twice that number of bullets.... I know they're there somewhere but just can't find the bolody things anywhere! LOL! Edited March 11, 2013 by shakari Quote Link to comment Share on other sites More sharing options...
Paul223 Posted March 11, 2013 Report Share Posted March 11, 2013 I have my doubts that a roll crimp 70mm case will chamber in a21/2 inch chamber with out wedging into the forcing cone a little, anyone have a roll crimp 70mm they could measure? Quote Link to comment Share on other sites More sharing options...
wymberley Posted March 12, 2013 Report Share Posted March 12, 2013 I'm still looking for something like 200 x .500 Jeffery cartridge cases and about twice that number of bullets.... Let us know how you get on with your 'Good Reason' for having that little lot here in the UK! Quote Link to comment Share on other sites More sharing options...
shakari Posted March 12, 2013 Report Share Posted March 12, 2013 (edited) I'm not in the UK I'm in Portugal and until about 18 months ago lived in South Africa for some years. Quite honestly, I seriously doubt I'd even ever consider moving back to the UK now it's the way it is. Edited March 12, 2013 by shakari Quote Link to comment Share on other sites More sharing options...
wymberley Posted March 12, 2013 Report Share Posted March 12, 2013 I'm not in the UK I'm in Portugal and until about 18 months ago lived in South Africa for some years. Quite honestly, I seriously doubt I'd even ever consider moving back to the UK now it's the way it is. That's me sunk without trace! Can do no other than admire your choice of country. Quote Link to comment Share on other sites More sharing options...
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