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Subject: breech mechanism
XeReX    11/30/2007 12:43:19 PM
can anybody gimme a link where i can find detailed info about breech screw mechanism????
 
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ArtyEngineer       11/30/2007 4:00:46 PM
 
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neutralizer       11/30/2007 8:53:32 PM
1.  Today breach screws are invariably used with BL ammo (ie no metal cart case) and larger calibres (including naval and coast artillery in the first half of the 20th century)
2.  A century ago they were also used with QF ammo (ie with metal cart case) and smaller calibres
3.  Today some BL ammo is used with sliding block breaches (Germany and UK)
4.  Screw breaches have 'interrupted threads', this means that closing them only requires a fraction of a full circle turn to screw them in the breach block which means they work fast.  Various mechanisms are used to minmise the breach distance the lever for opening and closing  the breach has to be moved.  The Welin interupted thread and Asbury breach opening/closing mechanism has been used with US and UK guns since WW1.
5.  Screw breaches are fitted with a 'lock' (as in 'flintlock' or 'matchlock' of history), this holds a 'primer' (also called a 'tube' by some countries).   Primers are usually percussion but electrical have been used by naval and coast guns.
6.  The most advanced screw breach today is probably that used with the latest version of the French AUF2 155mm SP, this has a primer magazine that loads primers into the lock automatically, more usually primers are hand loaded into the loc by hand.  The screw is not Welin. 
7.  When fired the primer sends a flame through the vent into the chamber where it ignites the cartridge in the bag of propellant.
 
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XeReX       12/1/2007 2:35:00 PM
Thanx a lot.. but infact I had already read that page.... This is rather basic info regarding Breech Mechanisms. I am looking fora bit more in-depth information about "Welin" and "Cylindrical"  Breech Screws.... Somehow I couldnt find that on net. I hope U coluld help me with that as well.
Still.... thanks anyway... and looking forwarrd to some more from from U
 
 
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neutralizer       12/2/2007 12:48:44 AM
Interrupted thread and stepped segments with varying radii.  The design achieves a large bearing surface but needs only a small turning movement to close.
 
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