What is the purpose of the Ejector Screw?

[Neuraleanus]

I've been looking for screws to better mount a Parker Hale sight onto a No. 4, Mk 1* that I recently acquired and I started to wonder about the so-called Ejector screw. All No. 4 rifles have one yet it doesn't seem to do anything. What am I overlooking?

Information

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[BVZ24]

It provides a raised bump inside the bolt channel in the receiver so that on extraction the rim of the cartridge hits it and bounces the cartridge out.

[Neuraleanus]

It provides a raised bump inside the bolt channel in the receiver so that on extraction the rim of the cartridge hits it and bounces the cartridge out.

Is there a spec on the bump?

[hayboy]

It provides a raised bump inside the bolt channel in the receiver so that on extraction the rim of the cartridge hits it and bounces the cartridge out.

Morning.
Just to add to this, I think more specifically it's for the ejection of unfired rounds. The friction against the side wall of the receiver is enough to eject the empty fired case as its extracted by the bolt. However, a heavier unfired round needs a bit more persuasion and this is where the tip of the extractor screw comes into play.
Best regards, Jon

[Alan de Enfield]

It only comes into play if you have an FTF.
As hayboy says - the "drag" of the case rim on the inside of the body is insufficient to flick the weight of an unfired cartridge out. The ejector screw is specifically located so that the case rim reaches the tip of the screw just as the bullet nose on a MkVII round (with an overall length of 3") clears the chamber
If fitting a PH sight using the ejector screw hole ensure that you buy the correct replacement screw that is long enough to go thru the PH sight mount, thru the body sidewall and just protrude enough to do its job.

[Neuraleanus]

It only comes into play if you have an FTF.
As hayboy says - the "drag" of the case rim on the inside of the body is insufficient to flick the weight of an unfired cartridge out. The ejector screw is specifically located so that the case rim reaches the tip of the screw just as the bullet nose on a MkVII round (with an overall length of 3") clears the chamber
If fitting a PH sight using the ejector screw hole ensure that you buy the correct replacement screw that is long enough to go thru the PH sight mount, thru the body sidewall and just protrude enough to do its job.

Yes, I've ordered a selection of BA threaded screws, which are not easy to find by the way, so I hopefully will be able to come up with something suitable.

[Alan de Enfield]

Yes, I've ordered a selection of BA threaded screws, which are not easy to find by the way, so I hopefully will be able to come up with something suitable.

The size you need is 3BA, but the length will be determined by the thickness of the sight mounting bracket.
The screw tip should have a slight angle ground onto it so that the 'angled flat points forward' when it is fully tightened up.
Be careful not to go 'too long' as you can get interference with the bolt and jam everything up.

[Bruce_in_Oz]

If anything like the same screw on a No1, it will be slightly "hard" on the small part that protrudes inside the body. Once firmly in place and smothered in Suncorite , it should never work loose of its own accord. A tiny dab of "light" Loctite will certainly do no harm, if you are "worried".

However ........

Bubba is everywhere and Murphy was an optimist.

[Alan de Enfield]

If anything like the same screw on a No1,

I realise this isn't what you were referring to but the No1 MkIII ejector screw is NOT the same as the No4 ejector screw.

The No1 MkIII ejector screw is a 'special' Enfield thread.
Comprising 0.1656" diameter x 37 tpi.
The original length was 0.205" but was later replaced by one 0.23" long.

[Bruce_in_Oz]

I realize the difference in the threads between No1 and No4 models. The similarity is in the function, not the thread form and pitch.

As much as a Gew 98 is "similar" to a Type 99 Arisaka or an 03A3 Springfield or M-17.

Maybe a better word might be "analogous"?