Help deciphering target barrel markings

[Surpmil]

I wouldn't touch the shoulder at all. Lap the washer with fine emery paper on a dead flat surface such as a piece of heavy plate glass, lapping plate or gauge block. A piece of very fine-grained granite countertop can be a cheap option too; a sink cut-out for example.

That way you are taking off thousandths at a time and can't go too far, too quickly as can easily happen in a lathe, apart from the alignment issues with a round, tapered exterior.

[jonh172]

Don't forget these rifles were only proofed for the 144gn NATO round. In reality they are 303 Brit. When the change over to NATO ammo the range shooters who wanted their rifles converted in Australia had to send them to Lithgow for the conversion,. Not all passed proof and were not returned. If your rifle did not have the proof stamp you were kicked of the mound NO DEBATE.

Thanks!
I’ll be careful, no sense “hot rodding” it, it’ll just be a fun mid range rifle and just “cuz”

---------- Post added at 10:07 AM ---------- Previous post was at 10:02 AM ----------

I wouldn't touch the shoulder at all. Lap the washer with fine emery paper on a dead flat surface such as a piece of heavy plate glass, lapping plate or gauge block. A piece of very fine-grained granite countertop can be a cheap option too; a sink cut-out for example.

That way you are taking off thousandths at a time and can't go too far, too quickly as can easily happen in a lathe, apart from the alignment issues with a round, tapered exterior.

Not gonna lie, this is exactly what I was going to do!

I have a piece of refrigerator shelf plate in my shop for these very purposes. I have “lapped” many M14 and M1 Garand gas locks this way to snug up perfectly.

Although I have a lots of experience trimming shoulders in the lathe, lapping the washer has the added bonus of not modifying the original barrel.

Thanks!!

[Alan de Enfield]

A little story about Breeching up washers from PL


I wonder how many of you read the thread on our sister Enfield collectors milsurp site regarding take-off barrels and the problems re-indexing them when used in another rifle afterwards. This is nothing new, not even with NEW barrels, especially ‘new’ old 40’s barrels that were still in the system until a few years ago. And dare I say it, but Savage spare barrels seemed to be the worst offenders.

At our big field and base workshops it wasn’t such a problem because we’d usually have a long racks of barrels, both new and almost new that we could use until we’d get one with the correct ‘hand-tight’ underturn that we could select for final fitting. Oh, yes……, before I forget, we always graded our barrels in quarters of life. If a barrel was in its first quarter of life then it’d be almost as new and so on to a last quarter of life where it was probably shot out. But shot out didn’t mean that it was duff or inaccurate either. Anyway, I digress………….. But don’t get the impression that it was just barrels where the breeching up threads were slightly out of index. It was the rifle bodies too. And if you got a rifle where the breeching up thread was ‘late’ (that is, commenced even a minute of angle late), then getting a barrel that would underturn was difficult. So I’ll take you through what could and would happen.

Sniper rifles were the worst because they were always at a premium and the Command AIA, (the Assistant Inspector of Armaments) would always specify new barrels for these but that was easy to say but sometimes difficult in practice. So where a new barrel couldn’t be found with the correct underturn, the breeching-up face of the body would be smoother-off with a smooth file, just a gnats knacker or as you wild antipodeans or colonial savages say, a RCH so that a datum surface was available. Then the best-fit barrel would be fitted until it read the correct underturn THEN a reading would be ascertained as to the thickness of material required to get the correct underturn. Lets say that in our case, it was .028”. That’s twenty eight thousandths of an inch.

Someone suggested that his gunsmith will insert a .028” steel shim and that’s the answer. Others have suggested that it’d be a good idea to gently swage the shoulder of the breeching-up face of the barrel, sufficient to take up the slack. DO NOT USE THESE METHODS. THEY ARE XXXX POOR ENGINEERING PRACTICE and verging on the best bubba practice you will ever have the privilege of seeing. Have you digested that?

This is what you do. Knowing that your barrel needs .028” underturn, get yourself a proper breeching up washer made. I’m not going to teach you or your machinist pal how to suck eggs but if you need .028”, then get the breeching washer made .128” THEN machine .100” off the breeching up face of the barrel (no, the breeching UP face, not the BREECH face silly…..). But I’ll let you into a secret. At our large Base workshop in Singapore, we were running major overhaul programmes of everything including L1A1 rifles. Then, someone noticed that the tough, hard, readily available and exact diameter required L1A1 breeching up washers were between about .055” and .070” thick. Now, we’d just take the barrel to the little Chinese fitter/turner (he had a big pile of breeching up washers in his tray anyway) and say .”028” please Lim” and he’d mount the barrel and machine away .032” from the breeching up face. You’d walk back to the Armourers shop, past Steve’s Magnolia ice-cream van where you’d spend the next half an hour discussing politics or the Viet-nam situation or the new flower arrangement in the church with the rest of the blokes……..Oh, I’ve gone off at a tangent again…… Anyway, armed with the new barrel with .032” machined off the breeching up face PLUS a new .060” L1A1 breeching up washer you’d know that .060” - .032” was .028” which is JUST the underturn we need to tighten the barrel to make it PERFECT on the flat-plate we used to ensure that it was perfectly tight, upright and square.

Is that simple enough? It might be a tad more thoughtful that a steel shim or a good battering around the barrel flange that won’t last twenty minutes but it’s how the pro’s do it.

There are a few afterthoughts too. I’m telling you this so that when YOU need to do the job, then YOU tell your gunsmith how its done properly. And go and buy a selection of L1A1 breeching up washers now, while they’re available. When a badly shot-out/rusty bore No4T Lyman TP rifle was recovered recently, it too overturned by as much as it should have underturned, even with a new barrel. Our main workshops were at their wits end as there were only a few barrels from which to select. So what method do you think THEY utilized? Yep, got it in one. And it shoots as sweetly and accurately as it ever did. And as for us young 20 year old lads discussing politics, Vietnam or Flower arranging in 60’s Singapore…………, then if they did, I wasn’t part of the discussion!

[jonh172]

Thanks Allen!!

I’ve read that countless times, printed it out a read it over and over while flying long legs.

I won’t even require 10thou off the shoulder or washer so swiping a little off the washer will work out great!!

Jon

[Surpmil]

Then the best-fit barrel would be fitted until it read the correct underturn THEN a reading would be ascertained as to the thickness of material required to get the correct underturn. Lets say that in our case, it was .028”. That’s twenty eight thousandths of an inch.

This is of course referring to a case of over-turn: where the barrel turns past the point it should be at when tightly "wound in".

I assume feeler guages were inserted between the front face of the receiver (aka: "body") and the barrel breeching face, and the barrel hand-tightened against the gauges until the correct under-turn position (or probably a little more) was established. That would give the depth the breeching washer needs to project past the existing face.

When wound on with a four foot handle on the wrench and well-oiled threads, there would be considerable "over-turn" to provide for I suspect. It is striking what a difference lubrication makes: what seems like the "tightness" of compression turns out to be in large part friction. Was reminded of this the other day in tightening something without and then with oil on the threads.

[jonh172]

Got the level out and measured the timing angle.
It was 25 degrees.

I taped some 220 wet and dry to my glass plate and removed a thou at a time until I got the timing down to 16 degrees.

I also cleaned the face of the receiver

Imgur: The magic of the Internet

[Surpmil]

Nicely done, though I wouldn't trust a piece of glass that thin to stay flat when pressed down on. Not easy to move the action over the paper without it tipping eh? I found you have to hold them near the barrel ring, press down well and start moving slowly.

Have often wondered how true the threads and front face of the receiver are to each other and to the bolt way. Would be interesting to make up a gauge to test that.

[jonh172]

I hear ya!
Like you said firm grip at the base and slow swipes.
You know you’re going too fast or not enough downward pressure when it starts chattering!

A receiver truing gauge should be easy enough for a machinist to make?
You should get one made and rent it out! It would pay for itself in no time!

[Surpmil]

Thanks Surpmil,
I’ll figure out the twist and report back!

It is also a 4 groove barrel, not sure if that was standard??

Yes, I believe they were all four groove. IIRC the lands have a noticeable bevel on the outside edge which could be mistaken for wear at a glance. Pretty sure they came in 10, 12 and 14:1 twists with 12 being the military pattern. They could also be bought without any threads or Nock's Form.

I'm sure there are people here who have more precise info.

[jonh172]

Picture shows the rifling and that it has a dovetailed front sight block for the globe target sight.

https://i.imgur.com/FC7MWOF.png

Being an L42 clone I’ll eventually have to remove the block to install the military front sight.

2 questions coming now:

1-were the blocks just soldered on? I see evidence of solder at the joint but was there a set screw or cross pin as well?
2-did the L42 use a standard No4 front sight and protector?
Would it be correct to simply install one after removing the block?