No4 Mk1/3 Origination and bolt head track

[Alan de Enfield]

So I'm still no further into knowing the original maker of the No4Mk1*

There is only a choice of two.

[ArtioZen]

I like rifle "forensics" though! My last pass / chance at finding its origin would have been ratifying an FTR removal of "US Property" marks as a policy or process- there could be feint traces remaining - when you try to look for such things, eyes and inferred images can be deceiving. Of course I can go through every inch of it again in a future total strip down for the tiny odd marks / tells that I may have missed this time. I also have a set or two of early low wall No4 wood which is more age appropriate for it - albeit marked by Sykes.

[Bruce_in_Oz]

The Ml1* bolt removal system probably "seemed a good idea at the time, your Worship", if starting with brand-new, correctly specced components.

However as bodies and bolts wear, the amount of "vertical' wobble increases and the lug on the bolthead floats up and down more. There is almost NO "vertical" support for the bolt body as it travels, apart from a bit of radiused surface in the top and bottom of the raceway. That "vertical float" causes the bolt-head to "rock" up and down and thus catch the ends of the gap.

A good TIG welder operator can build up the ribs with minimal "clean-up" required. The family motor-cycle mechanic and welding guru advises that a copper or similar shield with an extended centre tab to fit the "gap" and other edges to match the tapered profile of the slot will reduce the "clean-up" and act as a heat-sink.

How hard would it have been to fabricate a simple piece of "clock-spring" such that the bottom end hooked under the RHS sidewall and was clamped in place by the fore-end and with the top end folded in to "fill" the gap and having a small, turned-down tab to retract it? "What if" and all that jazz.

Oh, and chamfer the ends of the bolt-head "rib" for good measure.

[Maxwell Smart]

BSA didn't do the Mk1/1 to 1/3 modification for the UK Military.

But they did for commercial non-MOD contracts?

[Peter Laidler]

Yes, they did them convert Mk1's and 1/1's commercially. The reason was because they wanted to keep their own ROF's busy. BSA only got the No8 contracts later through gritted teeth for a couple of commercial reasons

[Lee Enfield]

...snip...
So I'm still no further into knowing the original maker of the No4Mk1* - although the FTR work is very good and thorough!

...snip...

This particular rifle appears to have been a Savage.

The "give away" is the second cut at the base of the front "pad relief" recess, and the "pad relief" itself - Long Branch never contoured their receivers this way.
Attachment 100668

[Peter Laidler]

Looking at engraving, I'd say that BSA never engraved their work as badly as that. That is dire..... Looks like someone did it in the dark, with his feet......

[browningautorifle]

Looks like someone did it in the dark, with his feet

So, that would be a "Fail" for a craftsman...? Pretty bad.

[ArtioZen]

Thanks Lee Enfield - An observation and snippet I did not previously know (I skipped receiver profile class). It does have a couple of Savage marked parts in the mix also. PL - Keep the engraving mirth coming - I'm dying with laughter here! It still shoots well IMHO Maybe optically occluded pedal finishing is the way to go?...

[Surpmil]

Thanks for the supporting info so far!

This was resurrected from a $101 sportster but shoots like a dream so is worth some effort to save. There is a light rub mark made by the lower side of the bolt head in the suncorite below the bolt head track. This tapers to be a heavier rub as the bolt closes - this may be the cause of the pressure challenging this bolt head out of the track at the gap. Ill look to add a chamfered edge to the bolt head to remove this rub and pressure first. if needed the end of bolt head groove chamfers can be next. I'll de-bur and round the receiver body rail edges too.

So I'm still no further into knowing the original maker of the No4Mk1* - although the FTR work is very good and thorough!

Worst case is its a very nice parts gun if the receiver continues to lose control of the bolt head. Or it waits for a good welder in my area. I was hoping to continue with this one in CMP meets and the like.

If you want to save it maybe take a piece of brass flat bar of the right thickness and profile the edge to match the bolt head guide, insert under the remaining rail and get the missing bits built up with TIG welding. I guess if you really wanted to get clever, you could take a piece of say, 1/8" flat and have that profile machined into one edge about 3/16 back from the original edge. That should leave you with a little projecting block that you could machine to fit precisely to the size of the original bolt head release slot. Then all your welder has to do is work up to the edges and build up enough for you to file it back to match the original profile of the rail. Then sell or rent it to those who want to repair their own!