Trigger Question on Mk 4

[Norton1]

Most of the time the trigger is a solid 2 stage unit. Pull till the two lugs engage and then a crisp break and it goes the rest of the way. But once in a while it is a single stage unit. Maybe once out of 15 times?

I've the CD on this rifle and everything appears to be good. The two bumps on the trigger look new, the sear end is as shown in the book, engages well, and is crisp off the second stage, and the face of the engagement lug on the bolt looks good. The trigger guard and plate is flat but does have a very small, 1/32", downward movement when the main screw is turned in. It is a MK II bolt in it -

I've pulled the stock off it and assembled the rifle without it and every time I work the bolt and trigger it works flawlessly. I even moved the main screw up and down a bit to see if that was causing any issues and there aren't any that I can see.

I have noticed in some pictures the main screw has what appears to be a metal bushing it goes through prior to engaging the threads in the receiver.

Any ideas on this? It's one heck of a surprise when it goes single stage.

Thanks

Steve

Information

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[Norton1]

Sorry - it's a No. 4 Mk 2 (least the bolt is stamped Mk II

[Peter Laidler]

It's not what the BOLT says, but what the body says. Come back when you can tell us what Mark/type of body the rifle has. But very basically, if it sa going from a perfect double pull-off to a single pull-off trigger occasionally, then something is moving slightly or an axis pin is worn.

But no one can answer the question until we know more

[Norton1]

Here ya go - Attachment 31782Attachment 31783

[Peter Laidler]

Ah, it's a Mk1. Check that the fore-end is fitting properly and not moving back and forth. Make sure that the trigger guard is FLAT. Contrary to what some amateurs will tell you, the trigger guard is not, nor has it ever been used as a medium to adjust the trigger pull-off. Replace the sear and trigger axis pin as a matter of course..

Oil, assemble and test again.

If it is STILL giving you the occasional single pull-off go for the bolt and see that the striker is dead straight and that the cocking piece is tight on the striker.....................

I could go on and on but most of it is pretty obvious.

When you've reached the end of the line, go back and stone a little from the radius of the LOWER trigger bent. That'll give you a tad less first pull. But without the rifle on the bench, it's all conjecture

[Badger]

With thanks to Advisory Panel member Peter Laidler, check his article presented in two parts in the Technical Articles for Milsurp Collectors and Re-loaders (click here).

"The Trigger Pull-Off" - Part 1 (By Peter Laidler) (click here)

"The Trigger Pull-Off" - Part 2 (By Peter Laidler) (click here)


This interesting article is accompanied by a detailed photo montage of a previously damaged skeletonised No.4(T) rifle, used as a training piece for budding Armourers to learn with and develop their skills. As Peter says "It appeared that this ‘rifle’ had never been finished as a ‘T’ as the front pad hole had not been drilled. During bead blasting after a hard life as a skeletonised rifle, it was established that the screw had sheared off and simply been made off level. Drilled out and extracted, it’s back to its former self. Waste not, want not as they say…". Other photos in the article show the clear interaction of the sear, cocking piece and trigger during various phases of its operation.

Article Extract .....

Pictorially, this shows the trigger at the end of the first pull, both ribs touching the trigger bent or flat of the sear with the sear nose at the extreme edge of the cocking piece………, just ready for the off.


(Click PIC to Enlarge)

Hope that helps …

Regards,
Doug

[villiers]

I have noticed in some pictures the main screw has what appears to be a metal bushing it goes through prior to engaging the threads in the receiver.

If it´s missing on yours, you should get one. Just hope you haven´t squashed the wood by overtightening the main screw.

[Norton1]

Thanks all - and I did read both of those articles prior to posting.

And would anyone have the dimensions of the bushing? And I also hope I have not squashed the wood.

And what would be the best material to make the pins for the sear and trigger? Mr. Wadham's book talks about a tight trigger and what to watch for with that so I could put the unit in the milling machine and redrill them to accommodate a tighter trigger. By his measurements I am within tolerance on the trigger play.

Thanks
Steve

[Brian Dick]

Replacing the axis pin should tighten it up as Peter said. Why redrill and go to a larger size? Seems extreme to me. I've got hundreds of bushings here if in need. You need a long one you can fit properly using Peter's article.

[Norton1]

Brian - not to belabor the point but I have a small machine shop and I think I can make a bushing out of stainless, or any other material for that matter, rather than incur the expense of buying one. That's why I was asking for the measurements for it. Peter's article does not address the bushing per se but says "After ensuring that the collar is a PERFECT fit and is nipped between the body" which leaves me wondering how I would determine that fit. I can make the collar tight to the wood and the Main screw but how about length?

I'm a retired Marine Corporal. I don't have a lot of money so if I can manufacture what I need it saves me money and provides a lot of gratification in doing the job myself. Any assistance is very much appreciated and this forum has provided a ton of it!!

Thanks
Steve