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I've never seen this type of gas block illustrated previously so I thought I would get some pictures of it and post them.
The flash hider, barrel and receiver are all B59 coded, ie. 1959 manufactured.
There is no front set screw to lock the front sight in position.
Very interesting screw setup.
|We can't see the front of the gas block where you'd expect to find the SCREW, securing, foresight. I don't think that the 1960 date has any real significance here, being simply a spare barrel used for a trial. In early production the hole for the foresight went through, down and into the gas plug and piston chamber. The gas would clog up the hole and penetrate into the thread, effectively locking the foresight into position. And no amount of soaking, heating or wrenching with the comb. tool would shift it. But what WOULD really shift it was one of the crunchies using his super strength comb. tool - or better still, a pair of snipe nosed leatherman pliers that would shear the blade off. Don't laugh, they'd even shear them off without unscrewing the locking screw as well..... That used to be a Y repair needing a new barrel
Tankie and Skippy and KtK will have or remember the jig that could be used to accurately align the drill to drill out and retap the (5mm metric fine?) thread.
I believe that this barrel was a trial to ascertain whether a side-clamped block/blade would be a more robust method of securing and eventually loosening the blade. Never seen one but remember and know the problem and the adopted repair. The alternative was to drill and tap a blind hole.
Hands up anyone out there in the universe who hasn't broken a tap off with the last tweak of a tap in a blind hole......... Be honest........
As Peter pointed out this would be a trail barrel, this one will be from BSA and will relate to the perceived issues with securing the foresight with the "SCREW, securing, foresight". There is mention about the issue of retaining the screw in the Rifle Steering Committee (RSC) minutes. The arrangement of the screws reminds me of what became the C1 / L2A1 foresight, except the Automatic had the removable foresights ears. I don't think the barrel is a 'spare' its been manufactured at BSA with the altered Gas Block, note the Gas Block doesn't have the the NSN, Maker and Year stamped on the left hand side and since Gas Blocks aren't swapped out by Armourers, its a factory made barrel.
I'll keep doing some more digging and see if I can find some more info
Pete, in 'Our' Day. Snapping a tap in a Blind hole was indeed a Disaster! NOT a problem these days. With the advance in Technology, EDM can now be enacted for this problem.
For those that are unfamiliar with this procedure. The affected part/item is placed in a tank of fluid (Not sure what type of fluid it is. I used to take the part to the workshop. Leave it there after explaining what I required doing to it) Clamped in a vice/ jig. & an upper 'Post' would be electricly lowered down with a Copper tip. Shaped to the part & size that was required. Basicly, the 'Post' came down itself, electricly driven & programed to do this. In an up & down motion. Whilst at the same time, a string electric current was fed to the Copper tip. This caused a spark to 'jump' between the small gap of the tip to the part needing work.
The electric spark ERRODED the metal, in a Pricise area that it was needed. Eating away the metal slowly & precisely. This process is known as SPARK ERROSION.
When the broken tap is eaten away completely, another tap can be run down the hole easily, to clean out the threads. And Hey Presto! You have rescued something, that WOULD have worked out quite expensive or in some cases. Virtually impossible to replace with another.
Kerosene can be used for the fluid in the EDM tank, I have a mate that has a EDM
:thup:Quote:
Originally Posted by nzl1a1collector
We used to get a firm in with one to remove the broken studs from the entablature on the MAN main Engines, in this case a square hole was produced to enable a square drive to be inserted (similar to a 1/2 socket extension, but much bigger) longest part of the job was getting all the gear in the Engine Room......
I wonder if I could get one to remove the 8BA screws sheared off by the unwary/unwise when they try to strip the seized turrets off their No32 telescopes. Bless 'em.......
We had an early variant of this at the metallurgy lab at Portsmouth uni, called an Argon Arc disintegrator and I have a feeling that it was an Australian invention
If you snap off a tap made from high CARBON steel, you can, at a pinch, break it up in situ with suitable HARD, small punches. High-carbon tool steel is VERY brittle but provides a good working edge.
High Speed Steel (HSS), on the other hand is a bit more "elastic" BUT, when you snap off a HSS tap in a blind hole, it gets VERY interesting trying to remove the stub at the bottom of a blind hole. Bashing it with a hard punch merely smears it into the partly-cut threads; VERY nasty.
There are special "tap-removers" that look like a bundle of pins and are intended to be used BEFORE any "violence" is visited on the offending remains. The nice folk at Brownells have a range of these in their catalogue. Any decent specialist tool supplier should also stock them.
EDM is the modern solution and has the advantage of not damaging the "goods" whilst removing the offending tap "parts".
Taps broken off in cast iron have been removed with the judicious application of strong acid (nitric) as cast iron is not as reactive with strong, CONCENTRATED, nitric acid as tool steel. (Method of LAST resort, NOT to be used on valuable gun parts).
A useful product in its own right, but this is about extracting busted ones.
Further to previous regarding the removal of broken taps:
The folk at Waltons have some suggestions, here.
And, from the world of clock-makers:
To remove a broken or damaged steel screw from a brass item, make up a paste of Alum and water, place over the broken screw.
Leave for 24 hours.
The screw will have been eaten away, leaving the brass intact.
This is the sort of info that used to be "common" knowledge.
Another example is the use of molasses as a "bath" to remove bulk rust from iron and steel items, without introducing potential hydrogen embrittlement and such. This is a SLOW process, but when restoring stuff from a century or more ago, what's another couple of weeks / months?
Using molasses, now I have never heard of that one! My long retired Father in law, used to be an antique clock seller/ restorer and he showed me some very old tricks for restoration. For instance "age colouring" small replacement parts in a tin with fresh oak shavings and ammonia. Some very clever tricks learned by resourceful clock makers having to use what came to hand down the centuries.
A lot of these are directly transferable to firearm restoration.
Of steel in brass on No32 telescopes. In the past I have been able to drill out the steel screws using the usual methods but where the bubba has had a go previously and totally xxxxxx up the situation I have resorted to cutting the corner off, and soft soldering a new corner onto the turret area THEN drilling and tapping afresh.
To be honest, I have nothing against putting right or correcting someones cock-up as it's a learning experience. Just so long as they STOP when it's gone wrong and don't compound the problem by continuing further and further into the sh......, er....., quagmire!