Breeching Up

[Peter Laidler]

Hello from wet, miserable, rainy Warminster, home of the Infantry, where Salisbury Plain has turned to mud. Ah, yes, breeching up.

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!

Information

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[limpetmine]

From this colonial savage, thanks! I always wondered just what the measurement of an RCH was, and now I know, .028 inch!
And I always thought it was "just a skosh"...

... 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”.

[ireload2]

What did you do when you installed a barrel that appeared to be good but shot poorly? What types of inspections and tests were performed to identify the source of the problem?
Did you ever have barrels that had to be scrapped even though they appeared to be in good condition?

[jmoore]

From our rather limited samples, the Glock armorer's dept. declared an RCH to be 0.0025"! (circa 1989)

P.S. thanks to Lou Clark (don't think he's with us anymore)

[limpetmine]

I have since lost the opportunity to do any first hand investigation, therefore am at a loss and at your mercy to get it right.

From our rather limited samples, the Glock armorer's dept. declared an RCH to be 0.0025"! (circa 1989)

P.S. thanks to Lou Clark (don't think he's with us anymore)

[Peter Laidler]

We examined barrels thus. Visual inspection, Examination with gauges then range test from the Enfield rest for accuracy. Then zeroed weapon. If the barrel failed the visual examination we got a second opinion (unless it was pretty obvious of course.....). If it failed any of the others, it got the chop.

The main problem for new barrels that failed to zero were that occasionally the bore was eccentric with the tube. So it passed everything except ability to zero

[Thunderbox]

We examined barrels thus. Visual inspection, Examination with gauges then range test from the Enfield rest for accuracy. Then zeroed weapon. If the barrel failed the visual examination we got a second opinion (unless it was pretty obvious of course.....). If it failed any of the others, it got the chop.

The main problem for new barrels that failed to zero were that occasionally the bore was eccentric with the tube. So it passed everything except ability to zero

Peter,

Occasionally new condition barrels turn up that, for no apparent reason (bedding, sighting errors, wear, crown damage, etc), group well but have an MPI well outside the adjustable zero range of the sights.

I assume that these barrels are simply not straight - although its often not apparent by viewing the bore.

I know the factories had wise old gnomes and huge machines capable of fixing errant barrels, but have you ever tried to do this in the workshop? Is it a matter of trying to bend/spring the barrel in the opposite direction to the flying group?

[Peter Laidler]

No I've never tried but the old and bold used to tell us that if the last 6" of the bore was straight, then it would group. But, alas, might not zero! We also had a 'GAUGE, testing, straightness of bore' too that was 6" long by accident or design. I had an eye for barrel viewing but never attempted to straighten one. I lie..., I did do it once for an L12 sub cal barrel for an L1A1 and it worked but.............

An easier method was to remove the barrel, take it to the welders bay and ask them to gas axe it!

I was told that the very skilled barrel straighteners were only used to straighten the very expensive Bren and BESA barrels because these had extensive machining on the outsides that made them very expensive while it was easier to simply scrap a normal rifle barrel. Maybe Enfield Lock could ask his Lockies about this

[tiriaq]

An ex-RCEME armourer I know told me that the most accurate No. 4 he ever tested was rejected because there was no pressure bearing at the tip of the forestock. Even though it shot beautifully, it was rejected because its bedding was not up to spec.
I assume it was subsequently reworked so that there was the prescribed amount of upward pressure.

[gunner]

A not really professional test for the bore is to use a brigth white wall and glue a black sheet of paper on it. Now you must look thru the bore half in the white and half on the black. If you hold it exactly and the bore is straight, you can see the light semicircular shimmering from the muzzle to the chamber. If the bore isn`t straight the light is ending on that point the barrel begins to be bent. Hope that anybody can understand my bad technic english.

Regards

Gunner