Long Branch 69L Mk 1/3 gets a new Barrel

I’ll post more photos once I install the barrel. I finished reamed the chamber this afternoon. I did this with the barrel off the action. This always makes me nervous, as you can mess up the throat this way. I borescoped it afterwards and it looks good. Hopefully I did not bugger it up. 

The biggest problem I have had is getting the old barrel off.  These barrels are on tight. Finding a workable action wrench and barrel vice took me a while. The set I have seems to work, but it required a lot of sanding to get the tapered aluminum barrel vice bushing to fit the chamber reinforce. Despite being advertised as a Lee Enfield action wrench and barrel vice, the fit to the chamber reinforce was all wrong giving only a line contact.  I ended up wrapping an old barrel I had with sandpaper around the reinforce and chucking it in the drill press.  Then holding the bushing down over the sandpaper to get the right taper.  Even then, the barrel wants to spin in the vice, you have to put a lot of torque on the two bolts that clamp on to the barrel.  

One thing I don’t really like about the action wrench is that it relies on clamping forces as well, and it clamps right on the forward part of the action body over the threaded area. This must be squeezing the body down onto the barrel threads, which just makes it harder to turn. I wish I had drawings of the original action wrenches and barrel vice.  I thought about sending the barreled action off to Brian d**k to separate for me but I decided I didn’t want to put it in the mail. 

It’s much easier installing the barrel. The Criterion barrel comes with a set of breeching washers of four thicknesses in increments of .001 inch. The thinnest one seems to be the right one giving a 14 deg barrel under turn before applying any torque. The next size gave about 20 deg which I think is excessive.  My measurements of under turn are fairly approximate using an adjustable protractor held on the knocks form flat and movable arm held vertical to the body. 

I probably won’t get anymore work done on it until Thursday. 

What Ive done in the past, is mark each side of the block onto the barrel with a #2 or grease pencil and carefully file but using a small triangular file.

Ive also used a hacksaw when doing pinning and carefully on other systems opening up the cut with needle files. Like one would do when making a dovetail.

If its done this way, the edge of the cut can be peened over to tighten up on the pin if necessary.

A trick associated with using a hacksaw blade is to grind one side of the teeth off. That way you can control the width of the cut and keep the cut straight. This is a good method for fixing buggered screw heads that are just peened over and dressed off nice and smooth again.

As for how it was done originally I always assumed it was done primarily by hand fitting on initial assembly. 

The reason for my thinking is, sometimes when swapping barrels stocks and what have you, the block for the sight will interfere with the front of the stock and the sheet-metal bands that reinforce it.

Often theirs not much room to work there if the original slot has been cut because of the diameter of the pin and how distorted they become.

For this reason I would assemble the fore-end to make sure the block is positioned correctly. Every once in a while one will need moved front a touch. The good news is, the lugs on the barrel will keep the block straight and keep it from wiggling left and right when you file. Just make adequate clearance to the stock is available.

I use the attached fore sight block (a clean machined one) to index the barrel with levels once its coming up to tight and then you can check it on a heavy piece of glass or a scrap of that ground granite they cut for counter tops by turning the barrel over to the block and the sight ears on the make do surface plate. Sometimes yo need to lever them a little bit to get them just so.

First, get the barrel leveled in the barrel vice. Unfortunately, can’t use the flat on the Knox Form as it is hidden under the vice bushing. I use a spirit level along the top of the front sight block band.

Barrel clamped up very snug, using a 2 foot ratchet and socket on the vice bolts. Powdered rosin on the reinforce and both surfaces of the aluminum bushing and the inside surface of the barrel vice.  Anti-seize lubricant on the barrel threads. Action wrench aluminum bushing also dusted with powdered rosin and pushed over front threaded area of the body. 

Measured the body under-turn at 15 degrees when snugged by hand.  Reynolds stated 18 deg was the requirement, but during wartime production, this varied a lot. The next size up breeching washer would put the underturn at over 20 deg, so I used the thinnest washer, 0.037 inches thick. 

Action wrench fitted and bolts torqued, not as tight as barrel vice, not putting nearly the torque on the wrench to install the barrel as it took to remove it. 

Torque action body to barrel until it is level with the front sight. I use a close fitting drill bit thru the back sight ears. The final tweak to align the body took about 100 foot lbs, an estimate, not using a torque wrench here. Had one foot up against the bench leg and gave it a good pull. 

Action wrench and barreled action body removed from the barrel vice. You can see the two aluminum bushings here.

Headspace checked. With two layers of aluminum foil (.0013 thick total) the bolt just closes on the 0.064 GO gage, so headspace is a fraction over 0.065 inches with the same #1 bolt head, just where I want it. Bolt a long way off locking on the 0.070 NOGO gage.

All done…

Torquing the barrel higher than I did makes it that much harder to remove. I don’t think I was anywhere near yielding any material, but with the next size washer, I might not get that barrel off. The barrel I removed had about the same underturn angle, and it was tough to get off, took about 80 lbs at a 4 foot lever arm (320 ftlbs).  The last barrel I did had about 12 degrees underturn, and it shot well. 

Page 185 of Reynolds book states the No. 1 and No. 4 drawing requirement for the breeching up angle was 10 to 14 degrees. For some time, this angle was substantially lower for the No. 4 in practice. The issue was studied and the final desired angle was 18 deg which was to give a standard breeching “load” of 120 lbs +/- 5 lbs. I presume he meant foot pounds of torque and not pounds force, unless the load is associated with the specific tooling used. I concluded 15 degrees should be satisfactory.