No 4 extractor spring question?

I have replaced the the extractor spring with one optained from NUMRICH. It took a bit but I stumbled upon the correct method thru trial and error before I found this postinghttps://www.milsurps.com/showthread.php?t=32620.
The spring launched a couple of times after reassembly. The detent on the spring seemed to be aligned with the recess in the bolt but the hole does not seem large enough to allow the detent to seat fully as it seems to be on couple of my No 4s and No 5s (detent fully engaged in the hole with the surface of the spring resting flush with the interior surface of the bolt head).
It is holding in place currently but I have not fired the weapon yet. Is is possiable the detent on the new spring is to large? Any input would be appriciated.

One never knows what you'll get from Numrich. Could be the detent IS too large.

I'd compare the bolt head AND spring against a known good example AND try to interchange extractor springs. That will identify whether it's the knib on the spring or its recess in the bolthead that's the problem

could it be a No1 spring?
cheers
Ned

I was going to ask if it was the wrong spring, but I wasn't that sure they were different...

Are they even original springs or new manufacture? I've got both, (originals), in new condition which takes the guesswork out.

Mr. Laidler had addressed the diffrences in the No 1 and No 2 springs in a previous post so I had eleminated that as the issue. As much fun as I had putting the spring in this I hate to disassemble another bolt head but I believe that is the correct next step in narrowing down the problem. I think it is an oversize detent in the new the spring as the holes in my other bolts appear to be the same size. I will try Mr. Laidlers suggestion and post the results.
Thanks to all!

Vastly different aren't they?

Quote:

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Originally Posted by Brian Dick

Are they even original springs or new manufacture? I've got both, (originals), in new condition which takes the guesswork out.

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I am thinking repro though it was not advertised as such. I need a coachwood upper handgauad for my Lithgow No 1 Mk 3 if you still have one I will order both.
Thanks

Numrich extractor springs the last while have been crap!!!!! Even with the correct tool, the springs have been snapping left right and centre. I suspect by a file test that they are WAY to hard and not properly heat treated. Chinese or Indian quality to be sure.
I'd suggest buying a box of NOS (new old stock) off Eslime or any other auction site; keep them around and sell of the odd one to recoup some of your money. You can find the NOS springs on auction sites for a decent price and normally a lot less on the shipping than Numrich. Especially if shipping them outside the USA.

I've got some coachwood front handguards but no rear ones. Send me your bolt head and I'll install the correct nos spring for you at no extra charge. Email me for details.

The experts were correct. Upon examination of the Numrich part alongside an original there are significant diffrences. The detent on the Numrich part appears to be a ball bearing inset into the spring as opposed the originals stamped or punched detent with a much smalled OD which snaps easily into the recess hole in the bolt head. The Numrich spring is much thicker and heavier as well.