Khaki Posted 26 February , 2012 Share Posted 26 February , 2012 Something I have always wanted to know, when a 'gun' is elevated in the firing position, what holds the shell in place before the breech is closed? khaki Link to comment Share on other sites More sharing options...
dannyhill86 Posted 26 February , 2012 Share Posted 26 February , 2012 The drive band, strip of soft metal at the base of the warhead that catches the rifling in the barrell and holds it in place. Or so I believe! Link to comment Share on other sites More sharing options...
centurion Posted 26 February , 2012 Share Posted 26 February , 2012 Friction - it's a close fit. Howitzers no different from AA guns in this respect. Link to comment Share on other sites More sharing options...
MikB Posted 26 February , 2012 Share Posted 26 February , 2012 There may be exceptions, but most AA guns were of a calibre where 'fixed' ammunition was used, with shell and cartridge already assembled. In that case, of course, the shell is held in position by the longitudinal strength of the cartridge case, usually with some clearance from the start of the rifling to guarantee a fit. Guns using obturators and bagged charges would require the shell to be rammed first to 'ring' the driving band into the start of the rifling so that it didn't fall back and crush the propellant charge when elevated. The 15" battleship guns used in the Queen Elizabeth and Royal Sovereign class ships were originally designed with an 'any elevation' rammer, the idea being that rate of fire would be increased by reloading the guns at shooting elevation rather than depressing back close to horizontal before doing so. In practice it was found that under battle-stress, the hydraulic systems powering the rammers might become 'starved', so that solid 'ringing' engagement wasn't obtained and the shell might follow the rammer back out of the breech on withdrawal. This could obviously present a very dangerous condition, difficult to remedy - so that in fact the guns were depressed back to some sensible angle prior to reloading. There was still some advantage in that this didn't have to be particularly exact. Off topic I know, but the County Class heavy cruisers famous in WW2 carried an 8" gun intended to be capable of 12 rounds per minute at elevations up to 70 degrees - presumably for heavy AA fire. I'd really like to know how this was supposed to be achieved - it certainly doesn't seem to give obvious time to depress and then re-elevate! Regards, MikB Link to comment Share on other sites More sharing options...
Khaki Posted 26 February , 2012 Author Share Posted 26 February , 2012 Fascinating subject and replies, I had visions of something like a spring powered lug that would have been depressed by the shell on entering and then depressed again by the closing breech. Thanks for the replies khaki Link to comment Share on other sites More sharing options...
MikB Posted 27 February , 2012 Share Posted 27 February , 2012 Fascinating subject and replies, I had visions of something like a spring powered lug that would have been depressed by the shell on entering and then depressed again by the closing breech. Thanks for the replies khaki If you inspect footage of WW2 German 88s firing - there's some on You Tube - it's apparent that some part of the round striking a trigger-stop causes the sliding block to snap across the breech to retain it. The loader forcefully accelerates the round into the breech, presumably so that he can get his hand out of the way before this happens. There's no sign of another crewman doing anything to shut the breech. I don't know the exact mechanism, but it's reasonable to think a cam at the limit of recoil opens the sliding block against a return spring and operates and sets the ejector, and when the thrown-in round resets the ejector to retracted position, this also releases the sliding block to close again. I'd guess if the loader fails to throw the round in with sufficient force, it may fail to release the sliding block and fall back out. If he follows the casehead with his hand right up to the stop, at best his hand will be violently pushed away by the closing block and it may be more seriously injured. I managed to stop the video at a point with the block about 2/3 closed, and the loader's hand was good 18" away by then. Regards, MikB Link to comment Share on other sites More sharing options...
Khaki Posted 27 February , 2012 Author Share Posted 27 February , 2012 Very interesting I'll try to see it. Thanks khaki Link to comment Share on other sites More sharing options...
MikB Posted 28 February , 2012 Share Posted 28 February , 2012 With an AA gun using an interrupted-screw breech like the 13-pounder, I would think the risk to fingers would be considerable, unless either the loader was closing the breech himself (if that was practical) or the gun was depressed to a lower angle for loading between shots. Regards, MikB Link to comment Share on other sites More sharing options...
johnreed Posted 28 February , 2012 Share Posted 28 February , 2012 In my day the Fixed Round was pushed home with a clenched Fist or in the case of seperate ammunition the cartridge case was push home again with a clenched fist. I my day the loader was issuee with a loaders mitt made out of leather. No loaders mitt listed on stores for 18 Pr. John Link to comment Share on other sites More sharing options...
MikB Posted 28 February , 2012 Share Posted 28 February , 2012 In my day the Fixed Round was pushed home with a clenched Fist or in the case of seperate ammunition the cartridge case was push home again with a clenched fist. I my day the loader was issuee with a loaders mitt made out of leather. No loaders mitt listed on stores for 18 Pr. John I can see that would work with the gun at an angle where the round wouldn't drop straight back out again. But you see pics of 13-prs on AA carriages elevated to 70 degrees or more. You'd never have time to swing the breech shut before the round fell out at elevations like that. The only way to save your fingers would be to carefully transfer support of the casehead to the breechblock as you lifted it to close - or drop the gun to 15 degrees or so and lose time, and maybe the thread of your shooting. I don't know if you'd get a gloved clenched fist far enough into the breech of a 13-pr to push the round fully home. Regards, MikB Link to comment Share on other sites More sharing options...
ianjonesncl Posted 28 February , 2012 Share Posted 28 February , 2012 From Drill Manual for 3.7 inch AA Gun. Many thanks for the link to Mike aka Skipman. Page 20 32, Duties of the Loader.This place should be filled by a strong man of medium height. He should have a special glove for the right hand. PLACE. Standing to the left of the gun about a meter behind and to the left of the breech. DUTIES. Place the cartridge in the chamber. Take the cartridge that is passed by the relayer, the right hand at the base and the left behind the ogive, turn towards the firer, elide forward on the left foot and place the ogive carefully in the breech, releasing it from the left hand; then slide the cartridge home by pushing the bottom with the palm of the right hryjd, the fingers open. As soon'as the shot is fired, without interrupting the maneuver, he announces to the range setter the proper range for the cartridge. Repeat also the fuze indications Page 21 (a) Moving the Safety Lock. The breech being closed and the safety lock in the roadposition, to take the firing position he grasps with his left hand the stop bolt knob, draws it to the rear and rotates clock-wise until its motion is finished. ( Opening and Closing the Breech. To open„ and close the breech, grasp the crank with°r both hands, nails downward, and rotate it to the end of the motion. At the end of the opening, eject the cartridge case. It is to be made with full strength. When the loader introduces the cartridge into the bore, the cartridge case rim bears against the ejector, pushes it forward and begins the breach motion. He then drops his hands to the side He holds the breech at the end of it's motion to prevent it's springing back, in case the bolt should not work. © Finishing up the Loading, In the case of large angles, if the loader does not succeed in pushing thc cartridge all the way, he finishes the loading with his left hand and closes the breech with the right. . Link to comment Share on other sites More sharing options...
johnreed Posted 28 February , 2012 Share Posted 28 February , 2012 Mike B The 13 Pr High Angle Mk 1 was adapted with A "Catch Retaining Cartridge" prevented the round from falling out when loaded at extreme elevation. John Link to comment Share on other sites More sharing options...
MikB Posted 28 February , 2012 Share Posted 28 February , 2012 Mike B The 13 Pr High Angle Mk 1 was adapted with A "Catch Retaining Cartridge" prevented the round from falling out when loaded at extreme elevation. John Aha! Thanks very much - like khaki's idea in an earlier post. Regards, MikB Link to comment Share on other sites More sharing options...
Rockdoc Posted 2 March , 2012 Share Posted 2 March , 2012 Whatever the catch mechanism was, it was easily removed. After the War, the converted guns that were still required were returned to standard condition. Keith Link to comment Share on other sites More sharing options...
johnreed Posted 2 March , 2012 Share Posted 2 March , 2012 Centurian With regards to your post No. 3 I have yet to have known about a fixed Howitzer round. John Link to comment Share on other sites More sharing options...
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