SMLE unlocks bolt on firing!

[303Guy]

Not mine - on a different thread this fellow had a problem with his bolt unlocking and I mean fully unlocking on firing. Not all the time, sometimes it would do nothing and sometimes it would half unlock then it would fully unlock! He took a video of it in action. It was been fired by a very brave ex-marine. He was smiling too!:-)

Non of the guru's (several armourers) has ever seen this before.

It was decided the probable cause was a worn bolt cocking piece cam (well, that was what I suggested and he thought it could be) so he's now looking for another bolt.

[Multigunner]

While bolt kick up is not uncommon full unlocking is rare. I would suspect a badly set back bolt and locking shoulders.
Theres a very small rake to the locking lug surfaces. Imperceptable when new but it can grow over time if unsuitable ammunition is used, such as MkVIIIz machinegun ammo. The No.4 can normally handle MkVIIIz ammo, but its not recommended for the No.1/SMLE rifles.
Bad lots of MkVIIIz have been reported. One batch generated over 60,000 CUP and velocity of 2900 FPS. Way too hot even for the No.4 and pushing the limit for the P-14 or even for MG use.
Another lot was found to have what looked to be 196 gr Soviet bullets substituted for the 174 gr Mk8 boatail bullets, these cartridges damaged some rifles in Australia years ago.

If theres a very noticeable rake to the mating surfaces the action body may not be salvageable.

[303Guy]

Just been examining my rifles and what I see is that if the bolthead pushes the striker too far back the bolt handle could conceivably lift to the beginning of that rake and that could well provide the impetus to cam the striker into the short groove. The owner says the camming face looks worn compared to mine. One of my bolts has too much lift from the bolthead but still some ways from the rake.