Reducing number of No.4 Barrel grooves to speed production?

[rayg]

Useful article here:

Firearms History, Technology Development: Rifling: Manufacturing: Broach Rifling

Broaching requires a serious upgrade in machinery from the basic “single-tooth” cutter method.

Once up and running, the production rate is quite high; the complex tool travels through the bore ONCE and the rifling is finished.

The other contender is cold (hammer) forging, as developed by out Teutonic cousins. They had to come up with a production technique that could keep up with their consumption of machine-gun barrels. When you have a fleet of thousands of MG-34 and MG-42 (and several other) guns at “work”, the demand for replacement barrels is ferocious.

The only fly in that ointment is the supply of suitable materials and machinery to make the mandrels and the rotary-hammer machines themselves.

The US used broach-cutting for some production; one notable product was all of the National Match M-14 barrels.

They also used a LOT of “traditional” machines.

Meanwhile, also in the US, another method arose: “buttoning”. The idea dates back to the late 19th century. However, it languished until the engineers at Remington refined it in the early 1940s

What a great link, fully explains the different rifling methods, Ray

[chanman]

Okay, a related question that's been bugging me just now. If 2-groove barrels were proven to work with the No.4 rifles, did Lithgow and RFI also make the same change to their SMLE barrels to save time?

[Bindi2]

Okay, a related question that's been bugging me just now. If 2-groove barrels were proven to work with the No.4 rifles, did Lithgow and RFI also make the same change to their SMLE barrels to save time?

Lithgow did not

[Bruce_in_Oz]

Don't know about RFI, but during WW2, Lithgow plant itself was churning out Bren and Vickers guns, with the rifle-making facilities moved to various "annexes". Last time I looked, the original Bren barrels were six-groove, right-hand twist. Our Canadian cousins certainly fitted barrels with "Bren-style", six-grooved rifling to a few No4s. But were they right or left-hand twist? Apparently there are a few Savage-made No4s floating around with six-groove barrels as well.

Because ALL of the barrels made by the system at Lithgow (and annexes), were single-cut on sine-bar machines, there was a move to make alternate (cheaper/faster) barrels for the rifles, but by the time that idea had done the rounds of committees and "evaluation", the war was starting to get very close to Japan and would likely not last much longer.

Drawing No. A-658 (traced from the original and updated in October 1944 and then amended in 1947), shows the standard, Enfield-style 5-groove barrel for Oz production.

However, it also contains a note:

"As alternatives, a barrel having two grooves diametrically opposite or four grooves equally spaced, would be acceptable."

Were any "alternative" barrels for No1 rifles actually made in Oz?

No idea.

[Peter Laidler]

It is always worth remembering that when you are geared up for quantity production (note quantity and not quality as I will mention MG cars in a second!) a production change, even to something APPARENTLY much simpler is always a challenge as it always means upsetting of ceasing or changing or altering something and ALWAYS at considerable cost too. So if your lines are running smoothly then it's best to leave it alone or, as in the Bren gun, change something a bit at a time over many many months.

MG and other bodyshells produced at PSF Swindon where I spent a month or so during the production engineering phase are a good example of this. Just to change from the earliest tailgates with multiple press-punched holes for the MGB/octagon/MG/GT to a three hole MGB-GT fixing cost many thousands and thousands of £££'s in press tool jig fixtures and line changes. Another apparently simple example during the same changeover period was abandoned simply on cost grounds and that anomaly remained.......

[CINDERS]

I think the 2 groovers are easier to clean IMO and given as stated larger bearing surfaces translated to greater accuracy, one can procrastinate on what's good and what isn't but when you think of the phases of production and War time pressures it really was a bit of rafferty rules if you got a shooter being at the lower rung.
Then you probably wouldn't as they would have been pulled from service after accuracy testing to give to the Marksmen, or fitted up into Sniper config.

To think of the 303 barrels being straightened by eye and a hammer then that is the real skill knowing where and how hard to strike the barrel to straighten it all through looking through it and the light reflected from inside the bore that is a real art long lost I surmise.
As now days you can have what you want and the limit is only determined by the length/depth of your pocket, all machined polished air gauged, lapped and yada yada with whatever your desire takes you I think Bartlein offers gain twisting as the Carcano rifles had in WWII (I might be mistaken there with the Carcano!).

P L did they ever do that type of thing when you were in service, hand straighten the barrels the old way or was it by eye and press or just machine.

Just like the old ways of making cars as Wes Harrison said you push the side of a car in now days and you get the ding but not the boing of the dent coming out!

[Peter Laidler]

We didn't straighten barrels at all. We did used to have an aiming rest set up with rollers to view suspects barrels The biggest offenders were the old L1A1 barrels. Even the AR15's/M16's were not in the easily bent league - nor do the L85's now that I think about it.

I seem to remember someone coming into the Armourers shop at Tidworth with what he said was a bent Bren barrel. Jeeeeeees, you'd have to go some to bend one of those. It wasn't bent but his aim was!

[Bruce_in_Oz]

L1A1 + excessively "vigorous" bayonet training = .....oh, dear.......

Ditto: grounded arms and unobservant truck driver.........

[Brian Dick]

Airborne drops with the M16A1 = ….. oh s--t……. Then there was the senior E6 NCO who lost his weapon on one of the jumps. He was always tough on us too about securing our equipment. That was a long night/morning. We combed the drop zone with M151 jeeps and 2.5 ton trucks using the headlights in police call fashion until we found it. Nothing really left serviceable except the lower and upper. All rebuilt and put back into service a few days later. We found just about everything else you could imagine too while we were looking for it. Had a truck load of stuff. Dang, it was cold too! A bit off topic. Sorry 'bout that!!

[Bruce_in_Oz]

A young member of our mortar platoon lost an L1A1 from a helicopter.

They were doing deployment training and the young bloke had to wrangle his rifle AND an 81mm mortar barrel in the back of the old UH-1H.

The chopper hit an "aerial speed-bump" at a fair altitude on the way and our hero had a better grip on the mortar barrel than on his rifle, and, as this was supposed to be a "tactical" deployment, the doors were open..........

A lot of grumpy diggers joined him in the ground search, but it was, to the best of my knowledge, never found.........Just another "interesting" "Loss and Damage" paper trail.

Extra duties???

Right up there with rolling the rations truck and the great "burning of the camouflage nets caper".......