Breech Block Failure 1916/1920 Erfurt

mrerick · 01-22-2021, 11:15 AM

In particular, the toggle train is, in fact, a long series of parts with axle pins holding the train together.

Wear at any of these axle pin points will contribute to headspace problems, and actually be additive.

I once had a LP08 that kept breaking axle pins between the breech block and the middle toggle. I finally solved the problem by replacing that axle pin with an oversized pin (by .5mm). which lengthened the toggle train and stabilized it.

Check and see how much play (front to back) is in the toggle train. That could have been the initial problem that let gas bypass the cartridge oblation ring and enter the breech area. Remember that the 9mm Luger cartridge body is slightly conical to aid in extraction. It doesn't take much toggle train looseness to contribute to a headspace problem and allow this to happen.

Something was loose enough for the gas to bypass the cartridge body before it came completely out of lock. If it didn't come through a pierced primer hole, it had to travel some route around the cartridge case.

As you replace the breech block, consider that the other two axle pins may be holding worn middle or rear toggles in the train as well.

01-22-2021, 11:15 AM	#11
mrerick Super Moderator - Patron LugerForum Life Patron Join Date: Dec 2009 Location: Eastern North Carolina, USA Posts: 3,920 Thanks: 1,377 Thanked 3,135 Times in 1,518 Posts	In particular, the toggle train is, in fact, a long series of parts with axle pins holding the train together. Wear at any of these axle pin points will contribute to headspace problems, and actually be additive. I once had a LP08 that kept breaking axle pins between the breech block and the middle toggle. I finally solved the problem by replacing that axle pin with an oversized pin (by .5mm). which lengthened the toggle train and stabilized it. Check and see how much play (front to back) is in the toggle train. That could have been the initial problem that let gas bypass the cartridge oblation ring and enter the breech area. Remember that the 9mm Luger cartridge body is slightly conical to aid in extraction. It doesn't take much toggle train looseness to contribute to a headspace problem and allow this to happen. Something was loose enough for the gas to bypass the cartridge body before it came completely out of lock. If it didn't come through a pierced primer hole, it had to travel some route around the cartridge case. As you replace the breech block, consider that the other two axle pins may be holding worn middle or rear toggles in the train as well. __________________ Igitur si vis pacem, para bellum - - Therefore if you want peace, prepare for war.