manthing Posted August 13, 2017 Report Share Posted August 13, 2017 How does one know to what standard their gun is proofed? I ask because I've just picked up a box of Gamebore Special Load 12g, BB, 36gms 70mm. And before I use them I need to satisfy myself the gun is up to the 3.25 tons psi that they generate. I found the proofing marks on the underside of the barrel block but can't find a specific proof Mark fro the pleasure quoted. The gun is a Lincoln no2 btw Any help would be appreciated Quote Link to comment Share on other sites More sharing options...
bruno22rf Posted August 13, 2017 Report Share Posted August 13, 2017 What exactly is stamped? Quote Link to comment Share on other sites More sharing options...
quentyn Posted August 14, 2017 Report Share Posted August 14, 2017 i thought if your gun was proofed for 70mm cartridges it was proofed for any commercial ( not home load) 70mm cartridge ( assuming non steel) or am i looking at this too simply ? Quote Link to comment Share on other sites More sharing options...
dougall Posted August 14, 2017 Report Share Posted August 14, 2017 A modern Lincoln in reasonable nick would be fine,presumably it is just the odd shell at Charlie? Quote Link to comment Share on other sites More sharing options...
Scully Posted August 14, 2017 Report Share Posted August 14, 2017 On 14/08/2017 at 04:44, quentyn said: i thought if your gun was proofed for 70mm cartridges it was proofed for any commercial ( not home load) 70mm cartridge ( assuming non steel) or am i looking at this too simply ?No, you're not. Quote Link to comment Share on other sites More sharing options...
manthing Posted August 14, 2017 Author Report Share Posted August 14, 2017 I will try and post a photo of the proof marks later. Yes I got a box as I've seen a fox moving from land I have permission on into the pens in some woodland I don't have permission on and was just trying to do the keeper a favour, no ulterior motives at all,,, honest. Quote Link to comment Share on other sites More sharing options...
wymberley Posted August 14, 2017 Report Share Posted August 14, 2017 On 13/08/2017 at 22:06, manthing said: How does one know to what standard their gun is proofed? I ask because I've just picked up a box of Gamebore Special Load 12g, BB, 36gms 70mm. And before I use them I need to satisfy myself the gun is up to the 3.25 tons psi that they generate. I found the proofing marks on the underside of the barrel block but can't find a specific proof Mark fro the pleasure quoted. The gun is a Lincoln no2 btw Any help would be appreciated Purely for info as you already have the answer. 3.25 tons per square inch. PSI is pounds per sqare inch. Never seen them but you might just find that the 3.25 is the required proof pressure for the gun in which they are to be used and not that which the cartridge develops. Quote Link to comment Share on other sites More sharing options...
neutron619 Posted August 14, 2017 Report Share Posted August 14, 2017 (edited) On 14/08/2017 at 07:44, Scully said: No, you're not. +1. If it's a 70mm chamber, it'll fire 70mm commercial cartridges safely. If it wasn't going to be capable of that, it would have gone bang by now. A gun is a pressure-bearing device operating well within the limits of the steel of which it is made. This is why firing a couple of proof cartridges and measuring the chamber / inspecting for cracks is actually sufficient to determine safety. Because metal only deforms / cracks when it's Young's modulus is exceeded (I think its Young's and not Hooke's), any force which doesn't exceed its tensile limit will be successfully resisted. This doesn't change with age - it's a property of the metal itself - so provided the gun isn't allowed to rust / degrade, a gun that safely fired 2¾" nitro cartridges in 1922 - for example - will safely fire them today. You'll also probably find that a good number of "high speed" clay cartridges produce pressures as high as (or higher than) many hunting loads. 36g isn't much shot on slow powder in a 12ga - you can load it with plenty of wiggle-room, pressure-wise. Edited August 14, 2017 by neutron619 Quote Link to comment Share on other sites More sharing options...
scotslad Posted August 14, 2017 Report Share Posted August 14, 2017 I know I have some shells which are 70mm that my SxS's can't handle pressure wise but were fine in the SA when I had it. But they were labelled magnum loads. I think from memory my shotguns had 900kg? marked on them but the shells had 1500kg? was a while ago now so my numbers could be out Quote Link to comment Share on other sites More sharing options...
dodeer Posted August 14, 2017 Report Share Posted August 14, 2017 Any 70mm gun will shoot any lead commercial loaded 36/38/42gr non magnum load. Quote Link to comment Share on other sites More sharing options...
manthing Posted August 15, 2017 Author Report Share Posted August 15, 2017 I can't seem to get a photo to pick up the marks.... I asked the question purely because it's the only time I've seen such a warning on the box, to be honest it put the willies up me a bit. Supplementary nubie question. Lol The gun is marked at 76mm so does that mean it will take 3" magnum shells Quote Link to comment Share on other sites More sharing options...
motty Posted August 15, 2017 Report Share Posted August 15, 2017 Sounds like you have a 3" magnum shotgun! Quote Link to comment Share on other sites More sharing options...
neutron619 Posted August 15, 2017 Report Share Posted August 15, 2017 On 14/08/2017 at 21:09, scotslad said: I think from memory my shotguns had 900kg? marked on them but the shells had 1500kg? was a while ago now so my numbers could be out I don't think there have ever been any shotguns proofed at 1500 kg/cm² or 1500 bar (close, but not quite the same pressure), but you may have seen cartridges indicating 1200kg or 1320kg for maximum individual pressure or equivalent proof pressure for the loading. The tables used by the CIP are here: http://www.cip-bobp.org/homologation/en/tdcc_public?page=1&cartridge_type_id=7 You can see - apart from all the pressure values associated with the different gauges and chamber lengths, that there is such a thing as a 3" 28-gauge cartridge, a 3½" 20-gauge cartridge and that they still, occasionally, encounter 14-gauge guns. Quote Link to comment Share on other sites More sharing options...
wymberley Posted August 15, 2017 Report Share Posted August 15, 2017 On 15/08/2017 at 10:04, manthing said: I can't seem to get a photo to pick up the marks.... I asked the question purely because it's the only time I've seen such a warning on the box, to be honest it put the willies up me a bit. Supplementary nubie question. Lol The gun is marked at 76mm so does that mean it will take 3" magnum shells Unless those were made for the USA market, I'm surprised that there aren't additional figures for suitable proof given in addition to the older UK tons. Re the 3" magnums - possibly but not necessarily. Have a closer look at the proof marks. Beware though, the gun is Italian so there will be a barrel weight stamped on there and it is possible that this can be confused with a proof pressure given in Kgs/cm2 Quote Link to comment Share on other sites More sharing options...
neutron619 Posted August 15, 2017 Report Share Posted August 15, 2017 Also beware that there are (Italian) guns out there which have 3-inch chambers and "Superior Proof" to 1000kgs, which is not equivalent to modern 1200bar "Magnum" proof. These were guns intended for use with home-loaded or other special types of ammunition. They're usually marked with "provisional proof", "final proof" and "supplementary nitro proof" marks, along with the number of kg/cm² (i.e. 1000). In practice, you'd probably get away with it, but it may be worth bearing in mind. Quote Link to comment Share on other sites More sharing options...
wymberley Posted August 15, 2017 Report Share Posted August 15, 2017 On 15/08/2017 at 11:58, neutron619 said: Also beware that there are (Italian) guns out there which have 3-inch chambers and "Superior Proof" to 1000kgs, which is not equivalent to modern 1200bar "Magnum" proof. These were guns intended for use with home-loaded or other special types of ammunition. They're usually marked with "provisional proof", "final proof" and "supplementary nitro proof" marks, along with the number of kg/cm² (i.e. 1000). In practice, you'd probably get away with it, but it may be worth bearing in mind. This highlights my point above nicely. One is barrel weight and the other, proof. Quote Link to comment Share on other sites More sharing options...
manthing Posted August 15, 2017 Author Report Share Posted August 15, 2017 You lot are just doing me nut in now...😁 Going to have to find a better light to photograph it in and you can then advise as appropriate. Quote Link to comment Share on other sites More sharing options...
neutron619 Posted August 15, 2017 Report Share Posted August 15, 2017 On 15/08/2017 at 13:39, manthing said: You lot are just doing me nut in now... Going to have to find a better light to photograph it in and you can then advise as appropriate. Ok - we'll take a look if you think it's worth uploading the pictures. However, if you can find the numbers "12-70" anywhere on it, probably inside a diamond, or if the second number is larger, you are unequivocally good to go. Quote Link to comment Share on other sites More sharing options...
wymberley Posted August 15, 2017 Report Share Posted August 15, 2017 On 15/08/2017 at 13:39, manthing said: You lot are just doing me nut in now... Going to have to find a better light to photograph it in and you can then advise as appropriate. Don't panic. You've got the chamber length sorted so just look for the figures as mentioned. Just one thing, the weight is in kgs so you might just see - dependent upon how neat the stamping is - a comma (or whatever) which is actually a decimal point. Ie, 1.200kgs. Two stars each inside a 'cog' side by side would be good. Quote Link to comment Share on other sites More sharing options...
manthing Posted August 16, 2017 Author Report Share Posted August 16, 2017 (edited) On the top barrel it's stamped 76mm and 18.4 The bottom barrel is stamped KG1.550 and 18.4 This should be a photo of the block Top line is serial number and what looks like makers stamp, bottom is I'm assuming the proof marks Edited August 16, 2017 by manthing Quote Link to comment Share on other sites More sharing options...
manthing Posted August 16, 2017 Author Report Share Posted August 16, 2017 For some reason the thumbnail won't open on my phone so this should be a linked full image. Quote Link to comment Share on other sites More sharing options...
wymberley Posted August 16, 2017 Report Share Posted August 16, 2017 (edited) OK you have the 2 stars we were after. Before you have a look here: http://www.shotguns.se/html/italy.html a brief explanation. When you scroll down to the 2 stars, you'll see a figure for PSI. When you divide this by 14.5 to convert it into Bars, it won't be quite right. This is because a while back some bright boffins at the SI (SI Units) - possibly to simply justify their existance - decided to change its value for some - not all - applications of which our needs fell into one such category. Consequently, if you use the value which was used at the relevant time - 14.7 - it makes perfect sense and you'll realise that you have a superior or magnum (lead) proofed gun. Edit: Oops, didn't see Post #20, there's the barrel weight as described. Edited August 16, 2017 by wymberley Quote Link to comment Share on other sites More sharing options...
manthing Posted August 16, 2017 Author Report Share Posted August 16, 2017 Thanks for that wymberley. And thanks to all that have participated in my ongoing education and befuddlememt. So I don't need to worry, I can load anything upto and including 3" magnum in lead shot? Not even going to ask about steel proofing lol. Quote Link to comment Share on other sites More sharing options...
Mr.C Posted August 16, 2017 Report Share Posted August 16, 2017 and AN is date code for 1985 Quote Link to comment Share on other sites More sharing options...
neutron619 Posted August 16, 2017 Report Share Posted August 16, 2017 (edited) On 16/08/2017 at 09:18, manthing said: So I don't need to worry, I can load anything upto and including 3" magnum in lead shot? Yes - the 17637psi pressure indicated by the marking exceeds 1200 bar which is magnum proof pressure. You're quite safe. However, the gun isn't steel proofed, on the basis of anything you've said so far. You meet the pressure requirements, which is the main issue, but the proof houses do other inspections / tests for a specific steel proof mark to be applied. Once again, you'll probably have no issues, but it's really up to you. Edited August 16, 2017 by neutron619 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.