Lee Enfield No1Mk3 Headspace issues

Tbolt

Tbolt

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Hi All

I need some advice here.

I have a 1912 LSA #1Mk3* that had a case head separation.

I measured the bolt head and it is 0.631

it closes on the Go gauge
it closes on the No Go gauge
it doesn't close on the field gauge

How much of an increase in bolt head length should i be looking for?
I have a bolt head that is 0.6325 would that be enough?
 
Not answering your question, but an observation.
I believe case head separation is usually caused by the firing pin driving the cartridge to the full-forward position prior to ignition. Upon ignition, the forward area of the cartridge expands to grip the chamber and the rim is driven rearward against the bolt face. I place a small elastic band on the case immediately in front of the rim to hold the cartridge against the bolt face. The small elastic bands the ladies use in their hair seem to work well. Keep your fired cases separated according to the rifle they were fired in and neck size.
 
Those rifles were meant to fire military ammunition and not reloads... so if you plan on reloading it would be wise to follow post number 2 so the brass will fire form fully, and not stretch backwards... and then when sizing, size only enough so the brass is not sloppy in the chamber... you want it to head space on the shoulder, not the rim.
 
And, to answer your question, going to the .6325 head is only .0015 difference and that's not enough to make a significant difference.
 
Tbolt said:
It's been a few years since I worked on it, but it was factory ammo not reloads. not sure about the chamber.
Click to expand...

You can have this problem with ammo on the first firing.

Compare the size of the brass before firing and after firing, I bet you will see a massive difference between the 2 brass cases, the fired one will have blown out and towards the muzzle too. Lee Enfield chambers, especially old ones are known to have generous chambers, it has a lot to do with the dented and dirty ammo getting stuck in the chambers in the Zulu wars.

The headspace is just on the rim, the shoulder has nothing to do with headspace on this gun. Since you have it pass on a field gauge then you are ok, not great but ok.

What is the ammo you are shooting? Have you tried some PPU or military ammo? The brass thickness of the PPU is similar in thickness as the military brass, commercial brass like Remington and Winchester is known to be thinner and cause more of these issues.
 
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