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I'm in the process of restoring a NZ carbine and i always like to strip down rifles for a thorough cleaning.
Look at the gunk in the extractor spring
Well i got this surprise…. the bolt head tread portion is cut and so is the striker tip.
''Luckily'' for me i had a spare striker and i also have a spare bolt i can take the bolt head from.
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I am not sure how the cut threads would affect headspace, the bolthead in front of the threads would be the same length. Also, the collar on the striker would stop against the back of the threaded portion so the striker tip would have to be shorter in order to get proper striker protrusion.
Probably the firing pin tip broke off or was cut at some point and a previous owner thought he could fix the problem by regrinding what was left and shortening the thread so that the collar on the firing pin could travel far enough forward to hopefully get the stub of the firing pin to project far enough to strike the primer.
That was no doubt a failure, as the cocking piece would then slam into the rear face of the bolt with ever dry or live firing, so the firing pin was welded and ground back to something like original dimensions. There was no repairing the cut thread of course.
To be charitable, this may be a souvenir of hard times rather than Bubba at his best.
Like gerard488 said i'm not sure headspace would have been affected by cutting the tread portion ?
The striker tip is shorter than on the other and welding evidence is visible on it so it was ''reconstructed'' at some point.
I wonder if the spring force would have been affected since it would have had to extend further, until the collar made contact with the shorter tread portion ?
Like i mentioned these come from a NZ carbine and like many of them it is stamped DP... so i don't think it's too far-fetch to assume the striker was also cut at the time of the stamping.
Someone worked on it operational again.
In any case i was more interested in it for its collector ''value'' than for it's shooting capability .... (i'm not really interested in shooting any DP rifle)
I know there isn't much monetary value in it but i feel any NZ carbine is still somewhat desirable and deserve to be dressed up again.
I'll post better pics of the striker tomorrow and of current rifle condition
Somebody using No.4 striker, instead of the proper one?
Just a thought (and a wild guess): Is it possible the previous owner broke the tip off of the firing pin, then turned the firing pin out (unscrewed) one or two turns to salvage what he could? If the fin was unscrewed, then the collar run foul against the base of the bolt head, necessitating shortening that as well.
As Surpmil pointed out, this may have been an expedient fix to keep the carbine in the field.
Nope the pin is way too long for that.Quote:
Originally Posted by Mk VII
It was broken off at some point for sure ... by who, we will never know.Quote:
Originally Posted by smle addict
One thing for sure is who ever tried to repair it wasn't a qualified gunsmith (god i hope not)
Here's a few more pictures.
The first is of the rifle when i got it ... at first glance it looks rater nice.
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Next one... the collar doesn't even touch the back of the cut bolt head. It is fully inserted.
Attachment 109940
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You can see holes in the welds making the integrity of the repair rater sketchy to say the least. The repair is also crooked.
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No idea what happened at the back but someone seems to have thought hitting it would help things.
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And last but not least the repaired tip being too thick for the hole he decided to enlarge the hole.... yet like i mentioned and showed above it is still too small.
Guessing by then he just gave up on ''fixing'' it.
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Yeeesh… who knows what happened there. At least it's in the right hands now, and you are doing it justice.
Bloody hell! That's some first class bubba work, looks like a blacksmith had a go with a big hammer and a forge, between making horse shoes!Quote:
Originally Posted by tatou
Well done for saving her, I have a soft spot for NZ issued rifles, well done!
Was wondering what was done about the tapered hole in the bolt head.Quote:
Originally Posted by tatou
The cocking piece would soon have started to loosen up slamming into the back of the bolt, hence the peening in an attempt to tighten it up probably.
I was handed one where the striker stuck fast in the bolthead when the trigger was pulled, making it difficult to cock. It was a de-act, so not safety-critical.
Eventually decided someone had put a No.4 striker in it.
Made a brass collar to go on top of the striker collar and keep it further back from the bolthead.
LE / SMLE strikers have a different thread from No4 strikers: 1/4 x 30 TPI (Enfield Special) vs 26 TPI (1/4" BSF) on the No4.
LE strikers are also longer because of the greater length of the "tail" on the bolt body and the cocking piece that fits over it. As for the bashing on the tail of that striker; maybe the lock-crew was missing at some stage and bubba "peened" the thread.
The striker is supposed to be an extremely "close" fit in the cocking piece. This is to be achieved, not by any "locking" effect of the thread, but by the striker body diameter and parallelism being a "perfect" fit into the matching, similarly precisely-made hole in the body of the cocking piece. "Wobbly' cocking pieces are a major threat to the safety of the trigger/ sear operation.
My initial thought was to save the bolt head by doing something like this but the enlarged striker hole worries me too much...Quote:
Originally Posted by Mk VII
Even though i don't plan to shoot it, being DP, i still like for it to be in as much good order than i can make it.
I have the parts so might as well use them. If i need them for something else i'll know where they are.
It still a work in progress so i might decide on another direction before i'm done.
---------- Post added at 03:26 PM ---------- Previous post was at 03:21 PM ----------
This is the most unsafe (at least that's how i felt) rifle repair i've come across so far.Quote:
Originally Posted by Bruce_in_Oz
I've seen deep pits but these were not cause by someone.
The person that did this probably fired dozens if not hundreds of rounds and never had problems, but the trouble who knows when it would have failed.
Most of the NZ Carbines were stamped DP & the firing pins tip were snipped off (mine still remains in that form) a lot have been "reactivated" over the years
I have two of them, one that was sporterized and the other that wasn't and both have DP markings.Quote:
Originally Posted by 5thBatt
Now that you mention it, i took a closer look at the full length stock one and the striker tip does protrudes but as a suspicious sharp edges (squarish) were it should be rounded off.
I'll have to check on that but my guess is that striker tip was also rebuild.
I'm in the final stage of finishing the stock on the sportrized one and was also checking the new bolt head, i noticed it would have to be fitted to the old body since the rotation is not enough. (sometimes you get lucky and they fit right off the bat)
Funny you mention you left your's in that ''snipped'' form...
I was thinking about mine and since i wasn't planing on firing it because it's a DP and that fitting a new bolt head would be pointless.
I would simply chop the ''fix'' off the old striker, fix the back end as best i can and reinstall both the old head and striker in the rifle.
I have no real reason to have it fully functional and working on matting the parts is kind of pointless (except to satisfy my OCD)
The bolt head is from a fully working bolt assembly and i would hate to risk not having it fit properly in case i need it for the future.
So i've finished restoring my second NZ Carbine (DP) and sure enough the firing pin looks funky.
Although the work on this one appears to be better, it lacks ''refinement''
Looks to me, he or they, lengthened a SMLE striker by cutting it and adding a length of pin to it.
What i am wondering, and maybe those of you that know about brazing can tell me is why was the cuts made like V notches... does it give the brazing more strength ?
Still not planning on firing that one neither but i am intrigued by the technique used (i know next to nothing about brazing or welding).
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When we welded something like that firing pin body we sharpened it like a pencil in the lathe. Then you build it up. You can't weld two ends together without filling it. Cutting the groove gives you edges to weld to. Then you carefully take it down. I had to do a '73 Winchester firing pin once...HAD to as there were no replacements.
Thank you for the explanation Jim. I had a feeling that was the reason but like i said, i'm pretty much useless when it comes to anything welding or brazing.:thup:Quote:
Originally Posted by browningautorifle
The fundamental difference between welding and brazing is that welding is achieved by melting and fuzing the original metal forming the joint, optionally adding material of the same type. Brazing and similar processes such as silver soldering or hard soldering uses a different metal to achieve the joint.
In brazing, the jointing material invariably has a lower melting point to the base metal, however the jointing action is achieved by the filler metal alloying with the surface of the base metal. Ideally the thickness of the layer of jointing metal should be as thin as possible so that the majority of the joint is made from alloyed material, which is usually stronger than the filler. Brazing alloys are usually made to have the lowest melting point achievable (eutectic alloys) which means that they go straight from solid to liquid with no "pasty" stage. This means that they are able to flow up narrow spaces by capillary action. As a result, the best brazed joints are made by cleaning up the jointing surfaces, but leaving only a small gap between them. When the joint is heated up and the brazing material added (after fluxing to chemically clean the surfaces!) the metal flows almost instantly up the joint giving a very strong bond.
Welding is a fundamentally different process. In welding, the base material has to be brought up to, or very close to, its melting point. In the old days, fire welding was achieved with alloys such as wrought iron by bringing the parts up to a "pasty" state where there was a mixture of solid and liquid material, and then hammering the parts together to achieve fusion. This was the process by which Damascus barrels were produced, but could only be done with certain alloys which had a "pasty" state as they melted. Welding pure metal or Euctectic alloy was only achievable when gas and electric methods of bringing steel up to melting point were developed. Welding is achieved by creating a puddle of liquid metal between the elements being welded. As the base material is being melted, you cannot achieve the fine gaps needed to create capillary joints. In a weld, the depth of the weld is limited to the depth of the weld pool, which is invariably less than the thickness of the material you are welding unless it is very thin (which causes other issues!). It is difficult in welding to fill gaps as the surface tension of the materials in the weld pool is quite high.
Welded joints are therefore much more of a surface effect than braised joints, and if a through weld is required, space has to be created to take the weld material which is added to fill the void. In practice a bevel is ground off the edges of the elements to be joined and a bead of weld run along the groove thus created. This is the reason for the V section in the welds illustrated above. One of the main criteria in weld design is the required weld penetration depth, and shallow welds are one of the primary causes of weld failure.
The choice of whether to braze or weld is not, as popularly considered, that of absolute strength, but more the nature of the join. A good brazed joint can be as strong as a weld if properly designed and carried out!
Someone once told me that the way of understanding welds and braised joints is to think about braising as using glue, whereas welding was more like using duct tape...!
Awesome, thank you guys for the great explanations. Wont make me a better welder but it does help a lot in understanding what is going on.
Cheers :super:
The other advantage of brazing is that the lower temperature of the brazing metal means there is usually no possibility of actually melting or distorting the pieces being joined, as there is in arc welding, nor the kind of instant contraction / "pulling" that makes it a bit of an art to maintain the relative positions of pieces being arc welded.
I'd have to disagree slightly that the depth of weld is limited to the depth of the weld pool, unless one means in each pass over the joint; one usually makes several passes over larger or deeper joints.
Or that welding inherently involves only fusing together the original metal of the parts being joined: only forge-welding does not involve the addition of new metal to the joint.
Brazed or gas welded joints are also generally much neater, and less obtrusive or likely to require treatment with a "welder's eraser".
The point I was trying to make was that in brazing, the fusion between the original parts and the braze material is a surface alloying process whereas in welding, the metal of the original part has to be melted and becomes part of the joint. This has two consequences, in that in a braise, the physical structure of the original part is only slightly affected (you can still get distortion!) but that the surface of the joint can be much larger due to the jointing material flowing by capillary action through the joint. In a weld this does not happen as the surface tension of the liquid in the weld pool keeps it local, and the depth of fusion in the weld is not much greater than the depth of the pool. As you point out, this is why, where a deep weld is required, multiple passes are required. A weld always results in the physical dimensions of the original part being changed, both from heating effects and as a result of liquification of the original structure..Quote:
Originally Posted by Surpmil
It is possible to create welds without adding filler, known as "autonomous welds" but only in a limited number of weld types such as outside welds in thin metal or where a weld can be run along the edge of a double flange. Autonomous welds are sometimes designed when welding exotic materials where adding a different filler metal would be an issue.
Most of my welding is using TIG, which I consider to be the best method for gunsmithing. It is as precise as gas welding, but without the need to give houseroom to acetylene, which often upsets insurance companies! You can also use TIG for brazing, although the filler rods are expensive. The only better technology is laser welding, which is a bit outside my budget!
Most common weld fillers for steel are low carbon. eutectic alloys that end up as fairly soft mild steel. You end up with a reasonably tough join, however it can be a bit soft for bearing surfaces. If you are doing welds to build up worn or damaged surfaces you might want to think about using one of the more specialised fillers or case hardening after dressing the weld.
I've just picked up a TIG, so it's going to be interesting to play around with. A garage sale here just yielded a full mid-sized bottle of acet., an O2 bottle, hoses, and and a nickel-plated Smith's oxy-acet torch, all for a tenner. Less than the deposit on one of the bottles now; though have no need of either I'll use the acet. and take them back for the deposits. I should get some propane tips really, especially for tasks like burning off powder-coating and stubborn accumulations of paint and dirt. A touch of air burns all such stuff off beautifully, but when one has to pay for the gasses it gets expensive quickly!
"hard facing rod" was what they used to call the sticks for wearing surfaces here.
' Enjoyed the chat.
"Let sleeping insurors lie" I always say. :D