How to evaluate Mk1 barrels

[bentwrench]

Hello all,

I am getting a parts kit prepared to build into a semi Bren. I have a nice kit MK1* type from Enfield..

I have a couple Lithgow MKII barrels that are new, never fired, and have the nicest bores I have ever seen on any gun. I also have a number of MK1 barrels ranging from very good to OK in condition. I would like to use both types for display and shooting. I can feel a difference with a .30 cal bore brush between the barrels, some are defiantly looser than others. I was thinking of machining some hard wax slugs I could push through the barrels and then measure them to get an idea of the wear. I could also machine a step gauge and check each end as well. I do have a small lathe at my disposal.

What is the best way to evaluate the bore condition, and what are acceptable tolerances for the Bren?

Information

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[Peter Laidler]

The BEST way is to scrub them clean and simply accuracy test them each individually. Armourers had loads of different gauges that would overrule the results of the accuracy test. But we don't work like that now. If it is accurate, then it's accurate and that is all the gun needs (unless you are shooting what we call 'overhead fire')

Sometimes a dire looking barel will shoot like a dream while a gleaminhg bore will shoot like a pig. Don't believe me, then just ask any rifle shooter!

If you REALLY want a load of bore gauge info, then ask again but the range and accuracy tet is the way to go initially

[bentwrench]

As a collector of military firearms I couldn't agree with you more, I have some rifles with sad looking bores that proudly outshout most new guns. A couple of the barrels I have show some throat erosion, and some rounded rifling. I am trying to narrow down which barrels to shoot, and which ones to clean up an use for display etc.

Ok so here is another question... Were the barrels matched to a specific gun? I have a few with "S" stamped on them which refers to a "Second" barrel for the gun with the matching serial number. Is it naïve to assume that any old barrel will work? Or is there a fitting process before a barrel can be used with a particular gun? I assume as long as the barrel nut locks up tightly the gun is good to go, is there more to it?

[Peter Laidler]

There were two barrels, each numbered to the gun of course and each barrel was to be used at the same rate so that they wore out together. Both barrels had to be the same mark/type and the second barrel was marked S. But in real life, we didn't mark the second barrel S because some dozyarses would think that this was S for SPARE and just shoot the sxxx out of the first barrel

Barrel fitting was done using different sized barrel nuts making sure that both were TIGHT but at the same time, both had to CHS up correctly and both had to allow the same amount of breech block clearance etc etc. THere's a LOT more to it than this of course..........

[bentwrench]

Anyway to identify the the barrel nut size, some mark or number? Also I have seen shims were these used for this purpose as well.

I can't assume the barrel that came with the kit was actually used with the gun before it was cut up. Building the kit will require setting the headspace to one barrel, I would like to be able to change barrels and fire the gun, not just for display reasons. I may need to procure and modify a second barrel nut to do this. Or I could get lucky have check a bunch of barrels till I find two that hold the proper head space, lockup, etc.?

Were these gun only fired with one type of barrel? Never mixed MK1 and Mk2? Even in combat as last resort?

[Peter Laidler]

There were shims of .002" and .003" I seem to remember but only two, to a max of .005" But NOT for CHS purposes, only for tightening the barrel. And I seem to recall that only ONE of the pair of barrels could be fitted with shims that were slid over the breech end exactly square-on using a special sleeve.

If I might be a bit bold as to say so, you're being a bit silly (I'll be diplomatic and leave it at that.....) in your last sentence, or a bit pedantic. As a matter of course Armourers were told to keep barrels as matched sets according to their mark/type. In combat or stress situations, what do you think?

You'll need to go some to modify a barrel nut. The ring part and threads are diamond hard. Barrel nuts are all numbered acording to size. But in truth, the size is a bit like rifle bolt head sizes or Bren locking shoulder sizes. Known only unto god! That's why we had a big box of them to pick and choose

[bentwrench]

I am sorting through a some mis-information I have been told. I appreciate your responces.

I was curious to the effect of using a gun (for what ever reason) with the wrong barrel(not one of the matched pairs). Was it generally the case a gun would function just fine? Or was this a risky coarse of action?