Considering some version of lapping a Lee Enfield barrel?

[Eaglelord17]

Meanwhile, in the Khyber pass a goatherder in a yurt is pounding out SMLEs with a forge, hacksaw, hammer and manually powered rifling machine made from bits and pieces of a GAZ-69.

Depending on crude people want to get, if there is a will there is a way. You can literally rifle a barrel just using a cutter (on a long rod), some lead, and another barrel. You line both barrels up basically nose to nose. You then pour the lead into the other barrel with your cutter in the middle. The lead works as a guide and it will guide your cutter to make a duplicate of the barrel with the lead plug whatever the rifling on that barrel is. Lots of brute force and ignorance required for that as well as patience. Takes a very long time from what I read on it, generally at least 8 hours. You also have to cast the lead multiple times. Basically no one does it this way anymore, but 150 years ago this was a option available to the gunsmiths of the era.

[Bruce_in_Oz]

Lapping a Lee Enfield barrel?

By my reading, SMLE barrels were "lapped" from Day Onoe.

Rhe "reason" was that the boffins were trying to claw back the muzzzle velocity lost when th e barrel was abbreviated from its priot "long' dimension.

This lapping was supposed to be "progressive", with the BORE diameter increasing towards the muzzle. B4ear in mind, this was the same era in which the Patt '03 bayonet was deemed to "shortfor actual combat. and the '07 clone of the Arisaka Type 30 bayonet introduced to regain the spirit of the pike. I have had Lithgow "H" barrels here , new in their packaging, that were measurably "belled" at the muzzle.

Arguments rage about bore-lapping? My reading indicates that those barrel makers that lap their barrels, do so on "over-lenght blanks, then lop off the first and last inch or so, to remove such belling that is caused by "runout" in the process.

Several rifle-builders regard the entire practice as "pre-wearing" an otherwise good barrel.

If you ever get to see the full process of "Hammer-forging' of barrels check out the "lapping machines".

These are ONLY used to precision polish the internal bore of the stumpy "blank", BEFORE it gets pounded into barrel (and chamber) shape. Interestingly these "stubby' barrel lapping machines operate vertically; with the "lap" slurping up the abrasive "mud" on each stroke.

[Rick]

Meanwhile, in the Khyber pass a goatherder in a yurt is pounding out SMLEs with a forge, hacksaw, hammer and manually powered rifling machine made from bits and pieces of a GAZ-69.

Nah... Fast Firearms LLC is just a few miles away at The Hajji Armory Formerly Known As Bagram Air Base.

[Rick]

Lapping a Lee Enfield barrel?

By my reading, SMLE barrels were "lapped" from Day Onoe.

Rhe "reason" was that the boffins were trying to claw back the muzzzle velocity lost when the barrel was abbreviated from its priot "long' dimension.

I'm still curious exactly what they did at the end of the barrel manufacturing process. From what I've seen in my short time in the business of manufacturing button/cut rifling barrels, the barrel blanks are drilled, reamed, and rifled with a bit of extra meat on each end that the gunsmith/receiving company doesn't have to worry about quality, belling, etc. If the barrel is to be sold as a finished product, you still start with a bit of extra meat on the end before finishing with chambering, barrel profiling, etc.

So, in wartime where I would assume an extra bit of metal at the end that was to be cut off would be considered to be a waste of a wartime strategic material and time. Was the rod stock for the barrels cut to the finished length of the LE barrel, then the drilling, reaming, and rifling began - no waste scrap?

If I had to bet $5, I would place my guess and bet on lapping not having anything to do with regaining velocity lost due to new variants of the rifle having shorter barrels. In a .303, the Quickload guys can do the 'what if' calculations, but I'm guessing lapping the bore will have little to do with muzzle velocity. I would take a wild arsed guess and say each 1" reduction in length might be worth 20 fps lost... that's where the issue is; lopping 5" off the original length barrel would cost you about 100 fps. But that's just a guess.

[Bruce_in_Oz]

That "velocity" equivalence caper is, apparently true. Bear in mind, that smokeless powder and jacketed bullets first entered British service in 1889. It was closely modeled on the German bullet for the Commission 88 cartridge.. Heavy and blunt-nosed. It all went out the window only a few years later when the crafty Germans introduced a much lighter, SPITZER bullet at a significantly higher muzzle velocity. The first serious adopter of this was the USA; .30-03 to .30-06.Britain tinkered with a "light" pointy bullet of approximately 150 grains. The catch was not accuracy or effectiveness, but getting it to feed reliably. The existing magazines were designed around a longer, differently-shaped bullet. Note the rapid progression through various marks of magazine before WW1. Eventually, somebody got it right with the Mk V11. A bullet of the same length as the old torpedo, but lighter at 174 gn. The same overall cartridge length was retained. The way most machine guns of the era worked is by dragging the rounds backward out of the belt, (Maxim) or "strip" (Hotchkiss) .

The .303 Mk V11 certainly proved itself as a rifle and machine-gun cartridge "One round to feed them all".

[Rick]

Thanks for the response Bruce. I have some general knowledge of the evolution in military bullets from about the time of the Minie ball design, but not as specific as you recounted.

My last comment was towards the suggestion that barrels may have been lapped in an attempt to regain some velocity lost due to barrel lengths decreasing rather than for some other reason i.e. a finding that it would reduce barrel fouling. I would assume that trials before production began would have supported that additional expense and time to do that, for whatever reason.

As to the possibility that lapping a barrel results in significantly increasing muzzle velocity, my experiences with 5.56 and 7.62 barrels being cut down looking for a uniform accuracy node (and my reading over the years) suggests that in a caliber with the expansion ratio of .303 British, you would see a velocity loss of somewhere around 20 - 23 fps for each 1" reduction in barrel length. I am certain that at some point in the past, multiple curious people have tested that with Lee Enfield barrels by cutting them down while chronographing the results.

Black powder would probably show some different results regarding how much velocity was lost per inch of barrel; probably a greater velocity loss per inch of barrel. But in either case, I can't see any significant recovery of velocity by way of lapping barrels after the drilling, reaming, and rifling is complete. I suppose it could be possible, but I spent a day carefully lapping my Long Branch rifle chosen for competition use in hopes of wringing every bit of grouping ability I could out of it, as well as preparing it for use with cast bullets in CBA military benchrest matches. I didn't see any significant improvement as far as chronograph results.

It is a fine barrel for cast bullet shooting in that I don't get any leading in the barrel unless I do something wrong, but it is quite possible that has little to do with the effort I spent casting lead laps to lap the barrel from end to end to be as uniform as possible. At the same time I also had custom bullet moulds cut to fit the ball seate/leade as tightly as possible to maximize obduration of the bore as quickly as possible. That was accompanied by lead alloy selection and heat treating the bullets after casting to best match the pressures of the loads being used. Other than if I had started out with a fugly bore on the rifle, a custom mould and some applied casting science probably had more to do with the results than all that time I spent lapping the bore.

I remain curious as to how manufacturers, especially Long Branch, made the barrels. If they started out with blanks of near finished length and then drilled, reamed, and rifled and when and how they did all the profiling and threading to end up with a barrel that could be screwed on to the actions properly indexed during times of wartime manufacturing. I'm not a collector or historian, but I wonder how many rifles every single day left armories like Long Branch in WWII or BSA or somebody else in WWI. Dozens per hour, certainly. If they lapped them prior to applying the finish and attaching them to the receiver, that would be an additional cost in labor, time, and expense. Minimizing those costs is reflected in the simple sight the Savage manufactured No. 4s left the factory with.