Criterion Barrels for No.4

[Peter Laidler]

There's FAR more to it than that Tiriaq....... Just from an Armourers perspective, we'd re-barrel one body with, say, 25 barrels to choose from and they'd all under or even overturn differently and even when it was all correct on the parallel gauge, the foresight block would/could be visibly off line and.............. and.............. Someones STILL got to set the machinery up and if they're doing it from drawings gleaned from back engineering, well.........

Just mark my words............. If they're serious, ask them to speak to someone who has breeched up a few or even had cause to manufacture just the breech end. And at the end of it, you've only got .010" CHS to play with unless you supply a set of bolts.

Not a job for the faint hearted. Just phone me and remind me of my bet at the end of December and we'll down a small scotch together over the phone!

Added later. Errrrr, I meant bolt heads and not bolts! Sorry

[tiriaq]

These barrels would not be the equivalent of service replacement barrels. They would be commercial barrels ready for final fitting, not unlike the barrels widely available for installation on any number of other actions. It is a standard gunsmithing job to rebarrel rifles. Often the 'smith starts with a barrel without any machining at the breech, and threads, chambers and headspaces the barrel. Barrels with the breech already threaded and the chamber cut almost to full depth are common. Machining a barrel shoulder to allow the barrel to breeech up with sights t.d.c isn't rocket science.

[Bruce_in_Oz]

I don't know about UK or Canadian service, but here in Oz, Lithgow actually produced No4 barrels for the target rifle fraternity into the 1960s. These were produced alonngside the "H" barrels for SMLE target rifles.

These Lithgow No4 barrels had the front sight locating lugs but no bayonet lugs and were apparently otherwise as per original spec.

One very interesting note is that the drawing specifies two "grades". What this means is that there was a "standard" barrel with the nominal "factory spec" thread start and a "replacement" barrel on which the thread start was advanced by 10 degrees.

This "advance" of the thread start was to allow appropriate breeching torque on installation on "pre-loved" receivers exhibiting crush of the internal breech thread and/or the front face of the breech ring.

Note: No4s and 5s breech up on the front of the receiver; SMLEs and older models breech up on the internal ring at the rear of the breech thread of the receiver, just like Mauser 98s are supposed to.

Trivia time: Mausers (98s anyway), use a true 55degree Whitworth form thread. Many commercial replacement Mauser barrels have 60degree threads; not good practice. No4s also have a true 55 degree Whitworth form thread. HOWEVER, SMLEs and earlier Lees and Martinis use a wierd "Enfield special" form of 49degrees, 40 minutes included angle. Pitch is the same 14TPI, diameter is nominally the same but with different tolerances.

[muffett.2008]

Bruce, I had a few Lithgow No.4 barrels, the front lugs were long and extended almost to the tip, doing both jobs.

[tiriaq]

The receivers that would be the candidates for these barrels - if they ever materialize - would be an extremely mixed bag. Provision for fitting could be an asset. Installation is going to be performed by civilian gunsmiths, rather than by service trained armourers. The tools will be generic. While it would be most convenient if the barrels could be simply torqued in, that would not be a reasonable expectation.

[Bruce_in_Oz]

The "embuggerance" with No4s is the lugs at the muzzle end.

I have done a couple of P-14 and SMLE barrels by carefully measuring the distance from the receiver front to the internal breech ring and from the receiver front to the face of the bolt-head (striker cocked to hold the bolt back against the lugs).

A few simple calculations give the maximum tenon length and how much headspace will result; tweak carefully.

Then cut the breeching thread and try-fit hand tight.

Remove barrel and cut chamber, then try-fit again.

The extractor cut should be done before final torquing up. If you have a Mk1* P-14, don't forget the clearance cuts in the back of the tenon for the 1* pattern bolt lugs

Once the barrel is "final" fitted and headspace is correct and chambering and extraction is satisfactory, jig up the whole assembly and cut the slot for the frontsight key.

With a No4, one trick is that when you profile the barrel before fitting, leave the muzzle-end section where the lugs are as a cylinder. Then after the back end is OK, set the assembly up and mill away everything that doesn't look like a sight base or bayonet lug. Unless you have a custom-ground shell cutter, this will keep you busy for some time.

Plan "B": Turn a simple collar where the front sight assembly goes. This should be a little smaller than the width across the usual lugs.
Then centre the base up in a chuck and bore out to a close match to the cylindrical lug on the barrel.
Slide on the base and line it up using the instruments of choice.
Douse the mating surfaces with "Super Wick-In" Loctite and leave for a day.
Carefully drill hole for locking pin. Note, you can be traditional and go with tapered pins, or be tricky and use a parallel hole and nested roll-pins.
Machining the bayonet lugs to actually retain a bayonet is an optional extra for bonus "tech-head" points.

Cheers

[trooper554877]

If you shoot under current NRAA rules and are looking at replacing a No4 barrel don't even worry about the bayonet lugs. Rules now say you don't need them to look like a genuine barrel just original profile,
Cheers
ned

[muffett.2008]

Yeah Ned, that's why they are getting away with reprofiled heavy target barrels in 308 and just necking down.
Some people call it cheating.

[Bruce_in_Oz]

But wait, there's more......

The blanks I have been playing with are 0.3025 / 0.311, 1:10 L.H. twist and made here in Oz in a joint experiment with the barrel maker. The first ones went into P-14s. These shot fairly well on first outing with boat-tailed Jugoslav ball. I just don't have a spare pallet or two of Mk7 lying about. The donor rifles appear to be "rufurbs" from the Baltic states and the bedding is "interesting" where it exists. The next step is to whip out the Decvon and tidy that area up.

However, I also run a No4 that has been fitted with a "pre-loved' barrel from an Omark target rifle. Because of the profile of the Omark barrel, and the lopping off of most of the chamber end, the breech reinforce is not quite the same as the original. The rest of the barrel is profiled as per a "proper" No4 and the front sight is attached as per previously described, with Loctite and roll-pins.

Yes, it is a .308" (nominal) groove job. The reason for this was the rapidly diminishing supply of "proper" ammo or projectiles. It is throated so that it will take Mk7 if I had any. It mostly gets fed the Australian 155gn BJD answer to the classic Sierra Palma bullet. These are used in my "real" Omark for other types of matches.

In the "No4.1", these work quite nicely, but the "compromise' throat means that I am probably not getting the best out of the barrel or the bullets. However, I AM shooting; that is, whenever I can get the time away from earning a living. The No4, (with only original sights), and using the BJDs, has a couple of deer to its credit, so I must have done something more-or-less right.

[tiriaq]

.30/.303 is an option that allows the use of the numerous fine .308 bullets.

Here is another way of mounting a service type front sight on a lugless barrel-
Obtain a scrap barrel, and soft solder the front sight base to the barrel. Cut off the barrel section with the front sight base, and bore out the barrel/base to suit the barrel. Cross pin or bond in place. The remains of the lugs may be just "cheeks" soldered in the grooves in the front sight base.