Longbranch No4 Mark I* 6 groove barrell

I have a No 4 Mk I* that went through an apparent arsenal rebuild in 1950. The rifle has matching bolt and receiver serial numbers, I've found the LB stamp on everyting but the trigger which is marked with a square shouldered 'S' (savage?). Both the receiver and the barrel have the Canadian acceptance stamp of the 'C' around a broad arrow. The barrell is blued, the receiver is parkerized, all the other parts appear to be blued. The odd part about the barrell is that it has 6 grooves instead of the 2 or 5 grooves that appears to be standard. I've attached images of the bore and the barrell markings. Does anyone have any insight on the 6 groove barrell? The flat on the top of the barrell is stamped 'CMK4' and there is a small diamond stamped about halfway to the muzzle.

I have C Mk4 barrels from 1949-1958 dated installed on various LB FTR'ed and newly manufactured rifles.

Probably a Savage barrel. How does it shoot?

Long branch produced 6 groove barrels around 1950, these barrels were made on bren gun tooling. See Skennertons "The Lee Enfield" page 313!

Definitely manufactured at CAL Long Branch. There'll be a little tiny "6" stamped on the bayonet lug too. They're not uncommon but not as common as the normal 1950's production five groove barrels. I think the rifling is the opposite twist from the five groovers too.

Bout the time you start to think you're winning the rat race they come out with faster rats. Now I gotta find a 6 groove LB.

Indeed, there is a 6 stamped on the bayonet lug. I'm going to have to set up a decent rifle range and see just how this shoots. I got it nearly 20 years ago, spent a couple hours scraping cosmoline off it and fired a couple of test rounds through it to make sure it worked. All my rifles, guns and pistols were oiled up well, packed in crates and stored in my brothers basement since 1995 when the Army shipped me overseas. Been out of the Army for a few years but until now I never had room to unpack them. It's like Christmas in my house :) every week I pull another rifle off the rack and research it.

Okay, I set up a target at 100 feet and took 5 shots while standing and supporting the rifle on a pile of lumber. Considering the low light and my degrading eyesight I think it shot a rather nice group. Got one a little higher than the rest but the other four are grouped 3/4 inch wide and 1.5 inch tall. Sights are set like they were when I bought it. I think a good marksman, or even me at a benchrest and actually wearing my glasses, could have gotten a much tighter group than this.

When I imported all of the Greek war reserve Long Branch rifles, there were 13 in the batch of 200 or so if I remember correctly. I sold the last one a couple of years ago.

We established during student projects that the amount of grooves didn't matter at all. 2, 5 or 6...., it was pretty well academic. What DID count was that the bullet was and remained stable in flight

\i forgot to add that it was critical that it remained spinning in flight too - but that is part of the stability issue

I wonder if the six grooves get more blow by than 2 groovers and a lower velocity as a result?
And on the same/similar question, wouldn't a two groove barrel generate a lot more friction with all that surface area against the bullet case and be prone to problems like build up or faster wear? I realize of course that they went on and performed well over many years, but an experts comments on the possible downsides will be interesting anyway,
cheers

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.

Anyone got one in their sticky paws?

Good point you raised RJ but in the great scheme of things friction really wouldn't come into the equation in short barrels simply because all friction generates is heat (I realise that this isn't technically/scientifically correct chaps but........) and this absolutely minute amount of friction heat energy is immediately swamped by the propellany heat energy.

2 groovers don't wear faster....... they wear at a slower rate purely because of the greater surface area

By fluke I happen to have one each of Savage and Longbranch six groove barreled rifles. The Longbranch is, of course, a re-furb while the Savage is an early Mk I (no star). My question is- why did manufacturers bother with 5 groove or 6 if there is no theoretical or practical advantage? The only answer that I can think of is that wear on the sharp edges that grab the bullet whilst spinning it up to a zillion rpm is distributed over a much greater length with 5 or 6 groove rifling. A meaningless anecdotal observation- my Savage has a darkened, pitted bore but still shoots very well.

Ridolpho

To be honest Ridolpho, the number of grooves is pretty well academic just so long as it imparts gyroscopic or stabilising effect to the projectile.

Peter: Indeed, I've seen no reference that suggests any difference in accuracy as issued- but what about longevity? Were there comparisons done after 5000 or 10,000 rounds? I would imagine this might be a bigger issue with machine guns (Bren).

Ridolpho

Quote:

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Originally Posted by Maygyver

Okay, I set up a target at 100 feet and took 5 shots while standing and supporting the rifle on a pile of lumber. Considering the low light and my degrading eyesight I think it shot a rather nice group. Got one a little higher than the rest but the other four are grouped 3/4 inch wide and 1.5 inch tall. Sights are set like they were when I bought it. I think a good marksman, or even me at a benchrest and actually wearing my glasses, could have gotten a much tighter group than this.

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What is the up pressure on the muzzle like?

Also is the main screw tight?

Is there any gap under the main screw?

what ammo?