No4 Mk1 half-cock issue

[Jack C]

Hi all I've been reading your forums for a while now and I'd like to say I really appreciate all the information on here. I recently bought a 1950 Longbranch No4 Mk1* and I took it apart to clean it, but after I put the rifle back together it would fire when on half-cock but it wouldn't before I cleaned it. I am pretty sure I put the sear back correctly but this is my first enfield so I could have done it wrong. Any input would be appreciated thanks.

Information

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[CINDERS]

Hi welcome to milsurps, those with the technical knowledge will be along shortly, as long as you did not end up with any spare bits I am sure your issue can be sorted pretty quickly. But until it does and just to be safe I would not be venturing out to put any rounds down the tube.

[browningautorifle]

Perhaps a few pics of the bolt from the area of the cocking piece and the sear. I'll bet it's something simple...depends on how exactly you took it apart.

[Jack C]

When I took it apart I removed the the bolt then I drove the pins out of the sear and magazine release. The sear will engage in the half-cock position but it looks like it wont engage far enough to properly seat into the notch that prevents it from firing.

[CINDERS]

I am probably wrong but if you pulled the bolt to pieces then re-assembled it with the cocking piece screwed onto the firing pin to far then the notch would be sitting to far forward for the sear to engage correctly that's if I am correct therefore your FPP will be to short in theory, here is the link to all of Peter Laidlers articles he is the go to person on this weapon also if I have got the bit wrong about the cocking piece then I am sure to be corrected.

https://www.milsurps.com/showthread.php?t=16948

Peters reply to another question asked ages ago (2011) but it gives you the FPP you need;
If the bolt heads vary by .003 to .005", then there's every chance that you won't need to alter the FPP that is between .040" and .050". If it's too long, then just stone it down making sure that you maintain the radius of the tip. If it's too short, then take the appropriate amount off the face of the bolt head tenon or skim said amount of the beating face of the striker.

But before you do any of this, make sure that what you are going to do doesn't affect the lift of the cocking piece and the overturn of the bolt head when you change it. The bolt MUST be looked at as a whole unit, accurately set up and not just the sum of a load of parts screwed together.

[Bruce_in_Oz]

There was a cartoon in an old "Saturday Evening Post" portraying a man and his son in the classic basement workshop, with the son looking quizzically at a pile of parts on the floor.

Dad says: "Don't worry, son. A thrifty tradesman ALWAYS has parts left over".

I have searched through the surviving editions at my brother's house, to no avail.

Always thought it would make a great "unofficial" workshop T-shirt.

[browningautorifle]

That all looks correct, how about the bolt? Did you strip that? Pics of the cocking piece?

[Peter Laidler]

In short, if it's firing off the half cock then it would appear that the under-cut half-cock bent is broken. Or the sear nose is broken and will not sit in the undercut as it should. But looking at the photos it LOOKS as though the undercut lip is sheared away.

[Jack C]

In short, if it's firing off the half cock then it would appear that the under-cut half-cock bent is broken. Or the sear nose is broken and will not sit in the undercut as it should. But looking at the photos it LOOKS as though the undercut lip is sheared away.

The undercut lip is still intact, I'm not sure what the issue was but I took everything apart and cleaned it again and it functions correctly now. Thanks for all the help guys.

[Bruce_in_Oz]

Be careful with those cocking pieces.

I have encountered some that have been "over-cooked" and, whilst providing a great surface for sear "let-off" are extremely brittle, usually fracturing at the half-cock notch. I suspect these may have been "WW2 vintage" parts, heat-treated without the use of accurate pyrometers, etc; dark days and desperate measures and all that.

Also, some "Range" types were inveterate tinkerers, with varying levels of knowledge and skill. "Adjusting" the face of the "full bent" (front face) was common and potentially dangerous practice. One quick test is to fully cock the rifle ON AN EMPTY CHAMBER and apply the safety. If it does not rotate firmly, and relatively easily into the "locked" position AND / OR the cocking piece is NOT seen to move slightly to the rear as the "lever" is rotated, there is a MAJOR flaw in the components or the set-up.

Shortening the cocking piece by "re-profiling" the full-bent front face does two things:

It cuts into the hardened surface and weakens the surface and, secondly,

It allows the cocking piece and striker to "rest" on the sear (hopefully "unadjusted" itself), thus misaligning the "full-cock" safety notch in the cocking piece, with the driving end of the "locking bolt" (safety lever).

Technically, the "safety catch" is that other bit that threads onto the 8-start thread and which moves inwards to prevent the bolt being opened whilst the "safety" is applied.

The full bent, (front face of the cocking piece) should show NO "curves" AT ALL. DEAD FLAT laterally and at the design angle of 86degrees and 10 minuted from the horizontal. Weak sear springs are a potential hazard, as well.

Finally, a clean rifle is a happy rifle, as you have discovered, yourself.