Is this a 2A / 2A1 or a No1 Mk3 ?

The 2A / 2A1 rifles were very marginal in passing the proof test and actually twisted the body so the proof testing was changed until they passed.

Any over pressure, or using heavier bullets than the 144-150g that they are deisigned for is like playing Russian Roulette.

If using heavier bullets you need to download the powder.

But - to answer your question - NO - a No1 Mk3 extractor (designed for extracting a case with a rim) will not reliably extract a 7.62 (rimless) case.

The profile and length of the 'claw' is very different for the 7.62 round.

I think you have hit the nail on the head.

Any "incident" that has cause such events should be checked out by a competent gunsmith before proceeding.

For you own safety please don't try to "shade tree 'smiff" this issue.

These are warnings of serious damage.

Awhile back. I inadvertently over charged a cartridge. Needless to say, the result was a bent bolt body. After taking a large hammer to the bolt handle, I was able to remove it from the reciever. I took an unissued bolt body and tried to insert that into the reciever and it stopped short of the lug recesses. I took the reciever to my friends machine shop and took some measurements. The slabside/leftside of the reciever had bent outwards from the lug recess back. The short lug on the bolt body was cracked as well.

Do not attempt to repair this rifle unless you have an extremely confident gunsmith willing to vouch for the safety and functionality of it and then give it a good think.

That (and the OPs problem) sound typical of the weak Ishapore body and an overpressure 'event'.

This was exactly what the Ishapore factory found happened when they tried to manufacture them from the "supposedly" superior grade of metal - they went back to the same metals as specified by the British and it just squeezed thru the testing.

Extract from “Gun Digest 33^rd Anniversary 1979 Deluxe Edition”

Article Author : Mr A G Harrison

Qualification : Former ‘Proof Master’ of the ‘Rifle Factory Proof House, Ishapore, India’

A bolt action rifle similar to the SMLE MkIII*, modified to fire the 7.62mm NATO cartridge, was produced at Ishapore, first in February 1965. The receivers were made of SWES 48 steel and with the NATO proof cartridge the receivers were found to distort with both the dry and oiled proof round. The material was changed back to the EN steel so now the rifles stand up better to dry and oiled proof. 

I’ve not shot cast loads in my No. 4 rifles, but it should not be difficult to load safe cast bullet loads.  Typically, velocities must be kept mild to prevent leading the bore, so I really wonder what went wrong here…

I wrecked a No4Mk1 action body. I was loading up 215grn RN's

and can only assume that one of those rounds was way beyond maximum charge weight. I felt the added kick, heard something make a crunch sound, and the magazine simply fell out. I tried to lift the bolt handle up and it was stuck solid. When I got home I removed the stockset and the scope and then got to work with my 5lb hand sledge. When I got the bolt assembly out you could visually see the bend from the lug contact points back. The short lug was cracked almost completely apart and the threads on the bolthead were flattened.  The only part of the cartridge to remain was the very bottom from the rim up to about 1/4". Everythingelse was pulverized brass.

I unscrewed the barrel, took off everything I could and then cut that reciever up, purposely leaving a couple of reciever bits out of the main bits so nobody could try to weld it back together...

Frightening - there is a lot of energy just a few inches away from our face.

I always switch off the phone and TV and tell the family not to disturb me (unless someone has died).

It only takes a fraction of a second of loss of attention and we can end up double loading, or squib-loading - which can be as bad as it can leave the bullet half way up the barrel and the next shot results in ..................

5th November 2019

That happened to me once in pistol reloading.  I’ve gotten in the habit to visually inspect all charged cases in the loading block (holds 50 cases) before seating bullets.  

Thought I had a picture somewhere - found it ............

7.62 on the left, 303 on the right

If specific over charges are involved this is the wrong place to discuss them.

You are all very experienced reloaders but other readers may not be.

I'm gong to let this ride because it has a lot of good info, but if unsafe reloading becomes a big part I'll be obliged to close it.

If you must discuss "Elmer Keith Commemorative Overloads" please go to PMs to do so.

Thanks.

No problem.

Just checking on the old "thread drift".

Dress the screw slot first.

use an impact driver?