Considering some version of lapping a Lee Enfield barrel?

[Rick]

Savage did 2 things that no one else did:

1. They straightened their barrels, still do, others did this too.

2. They lapped the barrels with an automated lapping machine, this is unique to Savage in that era.

The comment about Savage automatically lapping their barrels in a thread about 15 years ago leads me to mention this while wondering how they did it. Also curious if Long Branch did anything to the interior of their barrels after the drilling/reaming/rifling process was completed.

This personal experience might have some value for those considering whether there are potential gains to be made by lapping their Lee Enfield's barrel. Whether doing so by some version of 'hand lapping' or fire lapping.

In 2019 I became the 'ops manager' for a friend attempting to resurrect Montana Rifle Company after it was mis-managed into insolvency. MRC (the name at least) is in the process of being resurrected yet again by another company, but that is a different effort with nothing but the blueprints for the MRC bolt action. None of the original CNC machines or barrel making equipment.

MRC was briefly purchased and owned by Remington for the purpose of using MRC's century old Springfield Armoury surplus Pratt & Whitney gun drills to provide them with barrels for their AR-15 rifles. MRC was allowed to continue building barrels for their MRC bolt action boutique hunting rifles. All those barrels, whether intended for the Remington/Bushmaster AR-15s or for MRC's dangerous game hunting rifles were "hand lapped".

MRC's barrels from when Brian Sipe began the company until it's insolvency always had a reputation for accuracy. They were always "hand lapped" before being shipped to customers.

After, I tracked down some former barrel shop employees to begin the process of getting MRC back into operation, I scratched my head at how they had supposedly hand lapped each barrel while producing tens of thousands of barrels in the facility. I had carefully and painstakingly hand lapped two of my rifle's barrels practically one pass at a time using a poured lead lap with a stop at the end of the barrel to prevent the lap exiting the muzzle and a similar stop to keep the lap away from the ball seat.

For relevancy here, the very accurate 1950 Long Branch I did this with in hopes of even better accuracy and less trouble with cast lead bullets for practice and CBA military rifle competition had detectable differences in internal diameters (probably extremely minor differences only detectable by pushing a small cast lap through the length of the barrel). After I was finished lapping to the point of uniform force required to pull/push a lap the length of the barrel, I stopped. The bore of the rifle was more shiny, the bore diameter had only increased one .0005-" pin gauge - but I could still see very visible reamer and rifling marks. The results were slightly positive for both grouping of my best handloaded jacketed bullets and cast bullets were also significantly much easier to work with afterwards (this was before powder coating bullets was discovered).

Would I do it again? Considering that making and using the lap is easy, but it's also easy to be careless with the lapping and do more harm than good, probably not.

I was lapping what was already a well above average grouping new LE barrel, and few LE shooters are in my category of firing far more cast bullets down their rifle's barrels than they do handloaded jacketed. The grouping improvement I got for 10 round groups with jacketed bullets at 400 yards that I used as my test criteria probably wasn't worth the risk and the effort from what I started with. For a rifle with a barrel that has some degree of groddiness that I hoped to improve the grouping ability of, then I would do it again.

The MRC former employees, after we had gotten them on board as employees for the project, showed us what was considered "hand lapping" when manufacturing barrels for Remington AR-15s and MRC hunting rifles. The barrel blanks after drilling, reaming, and button rifling were clamped in fixtures about ten at a time. The employees then used a stout, short cleaning rod that had a long two-handed grip at one end and a worn barrel brush on the other heavily loaded with coarse steel wool.

The employees at the 'hand lapping' stations then went at the barrels with gusto, until at some point the company's standards on what the inside of the barrel should look like and .0005-" pin gauges told them was meeting company standards. This was circa 2019; Remingon had fled the AR-15 market in fear by then and Brian Sipe had bought MRC back from them at pennies on the dollar for what they purchased it from him. MRC rifles had a reputation for better than average accuracy as hunting rifles, apparently because they were all supposedly hand-lapped.

Like I assume most would be, I was aghast at this "hand lapping" process of going at drilled and rifled barrel blanks with coarse steel wool AFTER the barrel had been button rifled. Steel wool in any rifle barrel was a mortal sin in my life at that point, and I was watching these men go at it like an eight hour long crossfit exercise session... no overweight guys in that bunch. (Lots of complaints about tendonitis, however.)

After watching this, out of curiosity one day after work I did an experiment to see how much use/abuse of steel wool in a rifle barrel it would take to create some degree of what could be considered damage: visual rounding the top corners of the grooves/lands or increases in bore dimensions.

I took a scrap barrel (barrel had slipped during button rifling and had a small section in the middle where the lands/grooves were straight instead of the twist continuing), pin gauged it, examined the rifling, chatter and reamer marks with a borescope, and then copied the employees by going to town on the barrel with their coarse steel wool on a two handed cleaning rod.

It took a LONG time and a LOT of passes with that steel wool before the pin gauges showed me a .001" increase in bore diameter. Visually, I couldn't see any noticeable changes in the appearance of the top corners of the lands/grooves as I expected and was looking for. And... the reamer/button rifling marks were still very visible.

I suppose the only lesson learned is I no longer fear the idea of using a finer grade of steel wool to clean or rehabilitate a rifle barrel when the usual preferred methods aren't getting the job done.

Custom barrel makers like Lilja (who won't disclose his method) and McGowen (also in Kalispell MT and who also lap using the same method as MRC) also advertise that their rifles are 'carefully hand lapped' just as MRC said.

Lilja and McGowen are accepted as producing and selling very accurate barrels. Given that their barrels are made on far more modern gun drills and robotic cells than MRC's century old Pratt & Whitney drills and reamers dating back to WWI, if they're also lapping their barrels at some point in the manufacturing process rather than just inspecting and air gauging after the rifling is complete, there must be some benefit to lapping or they wouldn't be wasting production time doing it.

As far as fire lapping goes, I remember when that was the rage in National Match but I never felt any need at the time to mess around with it. I think there are justified concerns about firing abrasive loaded projectiles down a rifle barrel, versus careful controlled passes with a lead lap the length of the barrel. But when I compare a coarse steel wool coated bore brush rammed back and forth through a barrel blank by a sweating, muscular labourer on the barrel shop floor to fire lapping... I wonder just how much potentially worse fire lapping can be. (Ignoring the fact that fire lapping involves a barrel where the chamber has already been cut, whereas the coarse steel wool treatment involves just the finished barrel blank).

Lilja and a few other custom barrel makers for the precision rifle crowd out there say that you can lap a barrel TOO smooth - but I haven't seen any of them elaborate on what point a barrel is lapped too smooth.

In summary based on my brief experience in the rifle barrel manufacturing business, if I had a rough Lee Enfield barrel that I felt was lacking in grouping ability, I wouldn't hesitate to use some steel wool with a bore guide at the breech and a stop at the muzzle to prevent the steel wool from exiting the muzzle. Pin gauges in graduations of .0005" +/- (your choice) are relatively inexpensive on Amazon to have some control over your progress if you choose lapping.

Also wouldn't hesitate now to use steel wool to deal with leading or other fouling that other methods would not remove in a reasonable amount of time and effort.