Updated No.4(T) Scope Pad and Mount Blueprint Drawings

[Badger]

With thanks to member mudpuppy, we've updated the article titled Mechanical Blueprints and Specifications for the Enfield No.4 Mk1(T) Sniper Rifle (click here) in the Technical Articles for Milsurp Collectors and Re-loaders (click here).

Low quality pics shown below for illustrative purposes only

(Click PIC to Enlarge)(Click PIC to Enlarge)

Due to the poor quality of the originals, some of the drawings were challenging to read the very small print dimensions after digitizing, so Mudpuupy requested better quality versions from the "Pattern Room". Unfortunately, they weren't a lot better and as he wrote me, "I had to sit down with a caliper, my copies of the drawings, an original set of pads and rifle to confirm what was on the drawings. I edited the drawings and re-typed all the relevant information so it is clear now."

The addition to his original article, which included drawings and specifications for the scope mount, pads, pad screws, thumb screws and cheekpiece, now provides these additional higher quality digitized images of the No.4(T) scope pads and their receiver mountings. Refer to Note #1 under the Collectors Comments and Feedback section of the article to obtain these new updated blueprint drawings. If you want to get the best images, download the PDF file versions and then use the Adobe PDF reader to "zoom in" and blow them up so you can read the fine dimensions and specs.

Regards,
Badger

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[Peter Laidler]

There is a problem with working to the drawings and it's exactly what H&H discovered in the early days. And it's that the left side of the rifle bodies came to them in all shapes and sizes because it wasn't even a critical gauged surface (just measure a few if you don't believe me.....)! Just a few thou (.001") here and there are really nothing in themselves but on a No4T, this manifests itself a thousand times in accumulative error with the telescopic sight.

It was this very fact that decided H&H to pull the plug on the dribs and drabs of Savage, Maltby and BSA rifles and concentrate on ONE given source. The most constant in terms of quantity and just as importantly, quantity (to keep up the production line momentum) were BSA so from that day onwards, they only took from BSA.

From the drawings, you could assume that if you made the pads to this spec, fitted them, mounted a bracket and scope, you'd have an all singing and dancing deadly accurate No4T. WRONG.

H&H knew that even BSA's offerings were,at the very best, mediocre, they set about making PARTIALLY complete pads and put the partially complete pads onto the rifle. Then they held the barrel between centres (it's the barrel that directs the bullet don't forget.....) and machined the spigot on the front pad for depth to collimate (or optically align) the bracket for deflection against NOT the body, but the barrel. Then they machined the rails on the rear pad to collimate (or optically align) the centre line of the bracket for elevation.

Notice that now, regardless of the shape or thickness of the body, everything was machined AFTER the pads were fitted with one purpose. And that was that the centre line of the bracket would be EXACTLY collmated to the centre line of the bore. This was done on a couple of redundant lathe beds. And for those of you that don't believe this, then I have a few dozen of the partially finished pads, pulled from Sid Harveys pockets as he walked me around the factory.

And it is for this very reason that a member of the H&H staff was sent to Canada to get a grip of their cumbersome and oh-so-slow conversion line and speed up production there. In fact, they sped up production so much and fast that telescope production couldn't keep up!

You can always tell a fake by looking at the collimation of the telescope. Even the very best faked up No4T's, unless they know exactly what they're doing and have been in the game for a LONG time will make the mistake of copying the drawing or an old set of pads. But afterwards, when the rifle is zeroed, with the point of the grat high left or right or down in the side, then you'll know...........

If there is any call, I'll do a long article about exactly how they did all this but I seem to recall doing something earlier. Maybe someone can call it back if I did..........

[rgg_7]

Peter...I agree with you on the pad installation.....the datum of the pads must be in parrell with the the barrel bore. Very good info.

Brackets also have variation. How was a replacement bracket fitted to a No4T that lost its scope?

Lots of mismatched rifles that shoot very well so there must be a technical explaination.

[Peter Laidler]

Answer to RGG. If a rifle lost its scope in service, that was never a problem. As an example, (although the scope would really be in the case....) one that was air dropped in a container might have the ocular end smashed making the scope unserviceable so at Base workshops, they'd fit another telescope. BUT, as the collimation of the bracket matched the bore exactly, there wasn't really a problem. But replacement telescope was officially a Base Workshop repair.

As for a rifle that had lost its scope and bracket. Phew.......... If I was just a civvy shooter or 'gunsmith' or even worse, an 'enthusiastic amateur', I'd just get another scope and bracket, screw it on, grind seven bells out of the old number with my angle grinder then, with my new number set, set about punching in the NEW number and saying that it's deadly accurate and original. I'd zero it as best I could so that it was reasonably on for that day, then sell it on for a kings ransom.

In the real world of the Armourers shop in the Field or Base Workshops in Dusseldorf, things would be a whole lot different......... Do you realy want me to tell it all again..............? For a start, you just KNEW that you wouldn't be going off early and if it was sports afternoon, you wouldn't be doing sports either. Because you'd remove the telescope from the replacement bracket and rotate it, adjusting the point of the graticle so that as it rotated in the special rotation blocks set into the 'STAND, Instrument', the point was always on the same point at a distant object a mile away. This ensured that the point of the grat was in the centre of the optical screen and therefore exactly aligned with the centre-line bore of the telescope tube. Then set the range and deflection drums to mechanical zero The you'd mount that back into the bracket. Now for the tiresome bit.

You have to align the bore of the rifle onto a distant aiming point, say 1 mile away or a special chart and keep fitting the bracket with scrapers and fine fitting ensure that when you remove and replace the bracket, it fitted EXACTLY and aligned EXACTLY, every time to the optical axis of the rifle bore.

The worst one was deflection error because you had to scrape the meeting face of the front or rear pad or bracket because there was virtually no allowable deviation error. Elevation error was a little less exacting but still very tight. We had a tray full of brackets of course and we'd select the best and closest fit but it was never going to be easy.

Knowing that it was never a simple task, even with 15 or so brackets to choose from, can you now understand why I cringe a little when owners say that all the brackets and rifles interchange and it's a doddle to swop them around........ What they need is a day in an Armourers shop of the era with a crusty, wise old ex wartime or Korea war Sergeant who only accepts quality. Oe of my old Sergeants Stan Ayley used to say - and I used his words on many occasions myself later - '...near enough isn't good enough. But EXACTLY right is near enough.

Ah, yes, where were we before I was rudely interrupted.......... brackets..., yes!

There was also a repair policy later in the life of the No4T and L42 where we could refit mismatching bracket cradle caps. This wasn't a whole barrel of laughs either........... Luckily, at the later end of the L42 life, salvation came in the form of complete new replacement brackets that were also a reasonably good fit. And I've mentioned these Roger Payne offerings before. We didn't know that these new brackets from Ordnance were the brainchild of our very own forumer, Roger Payne who very astutely offered the MoD 50+ to eke out their dwindling L42 spares

[rgg_7]

Peter....greatly apreciate you taking the time to provide an answer to a nagging question. So many folks are mating brackets to scopeless rifles these days without regard to fit and function. Cheers, Ron

[Peter Laidler]

It's a fact Ron. Some of the original brackets mated to 'original' rifles are worse than useless but I don't say anything. Hopefully those belonging to the forumers are better. Quite clearly, some mismatches are truly genuine, like those refitted by us ....... or as genuine as can be reasonable and I can't see a purist having a problem with one of these either but the mix and match cowboys, well...............

[jmoore]

No known pics of the H&H tooling are there? Keeping the whole setup rigid enough for machining the pads whilst mounted on a "spindle'y" action-end bore plug has been a puzzlement for a while.

ETA:Quoted from above-

"H&H knew that even BSA's offerings were,at the very best, mediocre, they set about making PARTIALLY complete pads and put the partially complete pads onto the rifle. Then they held the barrel between centres...and machined the spigot on the front pad for depth to collimate... the bracket for deflection against NOT the body, but the barrel. Then they machined the rails on the rear pad to collimate (or optically align) the centre line of the bracket for elevation."
"This was done on a couple of redundant lathe beds."

I might find a use for that old lathe bed yet- it'll surely never turn parts- the headstock was gutted!

BTW The old Curtiss factory floor pics at the Smithsonian were absolutely essential when we were making fixtures for P40 assemblies.

[Brian Dick]

As one that's actually fitted a couple of reproduction brackets to unscoped/original rifles in years past, I have to agree with Peter. It's a bugger of a job and my hand hurt for a week after scraping the bracket for proper fit. I now have a handy tool supplied from a dealer in England for removing metal at the the front spigot bearing which will help a bit, (if I ever have to use it), but I didn't have it then!

[jmoore]

Brian, was it a custom ground tool, or something they just had? I've made some custom cutters, but its generally easier to farm it out. Mind you, all this is just an academic exercise right now, but might be interesting to replicate the original mfg. set-up for funnies. Scraping is a good (but SLOW) way to fit existing assemblies, I'm thinking of seeing what production dramas H&H had when starting from scratch. Its definitely not gonna be a for profit enterprise, I've learned better!

[Surpmil]

It's not generally recognized AFAIK, that it was the canny Soviets who were the only ones to overcome these issues in a way suitable to mass production. The PU scope mount can be screwed onto the receiver in reasonable alignment to the bore using the as-made mating surfaces. Then, to collimate for windage, material is filed off the two projecting lugs on the back of the mount until the scope is properly aligned. For elevation, two grub screws are adjusted and voila!

All this only works because the whole mount pivots both vertically and horizontally on the front 'ball'.

Not only that, but the scope can be aligned for cant by grinding more or less off one of the projecting lugs.

Someone either got themselves an Hero of Labour medal or saved themselves from a trip to the Gulag with that design, or both.

Of course it wasn't recommended to remove the scope in the field, but then snipers didn't do that much with the No4(T) either from what I've read.

rgg_7, ponder the "spindle'y" action-end bore plug a little more and you'll see how it could be made less 'spindley".