Breech Block Failure 1916/1920 Erfurt

Allen Brett · 01-26-2021, 02:32 PM

UPDATE:

I ordered and old "new stock" breech bolt that arrived in perfect condition. I swapped the breech out and put the firing pin and extractor from the original into the new block. The pistol will now cycle a new round with no problems (this was done manually and I did not fire the pistol). The next process was to check the headspace which is the current problem. I called all 3 gunsmiths where I live and they only do headspace work on bolt action rifles.

One of the three told me to pull the firing pin and extractor then use masking tape one layer at a time to see if the round would feed while slowly letting the toggle down. In short I ended up having to add 5 layers before the breech will not close when letting off the toggle slowly so the round is not being slammed in place. I used my calipers and the thickness of the 5 layers is 0.017. I found the following on a google search which took me to "LUGERFORUMS" and it stated the following "minimum headspace measurement from a SAAMI chart is 0.754" and the maximum headspace is 0.776", or 0.022" difference."

My question is using the factory round and having to add 0.017 before the shell would stop means I should be at 0.771 or slightly less which would put me under 0.776? If this is correct I should be within specifications to shoot factory loads?

Thanks,

gunbugs · 01-26-2021, 03:30 PM

The only way to actually check headspace in with the correct gauges. A cartridge is an unknown dimension, compared to a gauge. Tape is not an accurate way to gauge headspace. Bad idea. I would not take my firearm to said "gunsmith" for any work.

G.T. · 01-26-2021, 03:36 PM

A normal commercial 9MM brass case runs approx. .010" under the "GO" or minimum, so you .017"+ addition puts you right about in the middle of the range?... Make sure you check your first shot, and maybe a few more for primer damage/... best, til....lat'r...GT

G.T. · 01-26-2021, 03:38 PM

BTW, Allen, send the top half complete to me, I'll check it for you, no problem, no charge.... best, GT

01-26-2021, 03:36 PM	#3
G.T. Lifer Lifetime Forum Patron Join Date: Jun 2002 Location: Chandler Arizona Posts: 3,530 Thanks: 1,334 Thanked 3,711 Times in 1,014 Posts	you might be closer than you think? A normal commercial 9MM brass case runs approx. .010" under the "GO" or minimum, so you .017"+ addition puts you right about in the middle of the range?... Make sure you check your first shot, and maybe a few more for primer damage/... best, til....lat'r...GT

01-26-2021, 03:38 PM	#4
G.T. Lifer Lifetime Forum Patron Join Date: Jun 2002 Location: Chandler Arizona Posts: 3,530 Thanks: 1,334 Thanked 3,711 Times in 1,014 Posts	checking headspace BTW, Allen, send the top half complete to me, I'll check it for you, no problem, no charge.... best, GT

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01-26-2021, 02:32 PM	#1
Allen Brett User Join Date: Nov 2017 Location: Central Wyoming, USA Posts: 49 Thanks: 78 Thanked 26 Times in 13 Posts	UPDATE: I ordered and old "new stock" breech bolt that arrived in perfect condition. I swapped the breech out and put the firing pin and extractor from the original into the new block. The pistol will now cycle a new round with no problems (this was done manually and I did not fire the pistol). The next process was to check the headspace which is the current problem. I called all 3 gunsmiths where I live and they only do headspace work on bolt action rifles. One of the three told me to pull the firing pin and extractor then use masking tape one layer at a time to see if the round would feed while slowly letting the toggle down. In short I ended up having to add 5 layers before the breech will not close when letting off the toggle slowly so the round is not being slammed in place. I used my calipers and the thickness of the 5 layers is 0.017. I found the following on a google search which took me to "LUGERFORUMS" and it stated the following "minimum headspace measurement from a SAAMI chart is 0.754" and the maximum headspace is 0.776", or 0.022" difference." My question is using the factory round and having to add 0.017 before the shell would stop means I should be at 0.771 or slightly less which would put me under 0.776? If this is correct I should be within specifications to shoot factory loads? Thanks,

01-26-2021, 03:30 PM	#2
gunbugs Lifetime Forum Patron Join Date: Sep 2013 Location: Fairbanks, Alaska. Home of the best moose. Posts: 673 Thanks: 371 Thanked 1,202 Times in 407 Posts	The only way to actually check headspace in with the correct gauges. A cartridge is an unknown dimension, compared to a gauge. Tape is not an accurate way to gauge headspace. Bad idea. I would not take my firearm to said "gunsmith" for any work.