While thinking about self reliance I got to thinking about bullets.  That’s not surprising, considering cast bullets is my specialty.  In particular, bullets for BP cartridges.  The limited velocity is compensated for to some extent by weight.  Hence the big calibre heavy bullets in such rifles as the Sharps.  Weight adds momentum and thus allows more range than lighter bullets at the same velocity.  That’s all simple stuff that’s known ( I hope ) by all of us.

There are advantages to paper patched bullets.  Moulds are ( relatively ) easy to make.  Moulds are usually cherry cut or lathe bored.  For the amateur there are technical difficulties with both, related to the lube grooves.  Paper patched bullets don’t need lube grooves, so they can be made by drilling and reaming in a lathe.  Aluminium in particular is easily to machine with simple home made reamers.

Paper patched bullets can be cast from softer alloy than plain base or gas checked, so they hold together better on impact and provide an element of controlled expansion.<

If they are used with nitro powders they can be fired at jacketed velocities thus offering longer range than plain base, though it must be conceded that the advantage over gas check is not much.  Higher velocity offers not only longer range but also flatter trajectory and thus longer point blank range.

If a little extra work is accepted, gas check rifle bullets can be made in home made moulds.  The mould cavity is reamed without lube grooves as described above.  If the pilot portion of the bullet is gripped in a simple collet chuck the lube grooves and gas check rebate can be machined.  Antimonial lead alloy machines very easily and accurately.  I don’t mean machine each groove individually.  It needs some special but easy to make tooling.  Three or four cutting tools ground to the desired shape are mounted together on a tool holder, and two directional stops fitted to the lathe carriage.  The grooves are then cut in a single pass.  While I have not tested it, I’d guess that 50 per hour could be done.

Of course, then you have to find gas checks.  For several years they have been available at only a few dealers.  That will get worse.  They are also expensive.  That’s another advantage of paper patching.

[Originally posted to SATalkGuns -- Admin]

If government gets it’s way, there’ll need to be a lot of improvising done to secure arms and ammo in future.  I might have written about primers before but here goes anyway.  Large primers can be substituted for small primers but not the other way round.  It’s not difficult to enlarge a small primer pocket to take a small primer.  Needs a lathe and it’s time consuming, but those will not seem like big problems in an emergency.  About the only things to be cautious about are ejectors striking the primer in auto pistols, but that’s just a matter of checking the dimensions of your pistol.  The other thing might be that chamber pressures might be a little higher.  Wouldn’t be much, would just need the same caution as needed for any change of primer or other component.

Why would anyone want to substitute primers ?  Availability.  Might be circumstances when you take what you can get, whether at retail or in informal trade with others.  Also, in a survival situation, it’s a good idea to ensure that all components are interchangeable.  That is, don’t get caught with only small primers when your 308 rifle needs some.  What happens if SAPS takes all your guns ?  You’ll have to get at least one from wherever you can get it.  So you won’t have much choice of what it is, and thus what primer the ammo will need.  Yeah, I know common sense says make sure you’ve got some of everything.  But if you have to make a choice of one primer type only, choose large, at least you’ll be able to use them for any calibre gun you come by.

But I do foresee a scenario in which small primers could be used in cases with large primer pockets.  It’s time consuming but not technically difficult to drill and tap a hole in a case head, and machine and solder in a threaded insert with a small primer pocket and flash hole.  Not strong enough for nitro powder, but OK for black powder loads.

BP offers other advantages.  Converting berdan cases to boxer is risky because the pockets are bigger.  It was commonly done in the arms embargo days of the seventies but is risky because of leakage.  Lot of guys filled the gap with nail varnish but I wouldn’t risk it.  But BP pressures are so low that the nail varnish trick should work quite well.

Centrefire primers are more potent than the old BP primers.  I suspect that a small primer would ignite BP quite well even in a large case.  The low pressure of BP also means pistol primers can be used in rifle cartridges.   Then again I’ve never been entirely convinced that they couldn’t be used in nitro rifle loads.  44 Mag pressures are close to rifle than pistol pressures.  But whatever the arguments about that, it makes no difference with BP.

Something I’d like to know is how many BP rounds can be fired before fouling stops it ?  Must be a few, as the Lee Metford 303 loads were compressed BP.  Gas checks work by a scraping action.  Would they be any use in clearing BP fouling ?  Anybody know ?  Anybody care to load a 303 or 458 Win mag with BP and cast bullets to see what happens ?

[Originally posted to SATalkGuns]

I have just done a little job which, though small in itself, taught some lessons that might be of use to others.  It was a Tasco variable scope, one of those that has a graduated range drum for quick range setting in silhouette shooting and no doubt other disciplines.

The drum is really a sleeve that fits over the steel stem that actually rotates to controls the reticle.   The stem has an annular groove near the top.  The drum has a pointed grub screw in it’s periphery that engages the annular groove, by which means the drum turns the stem.<

The centre line of the screw is slightly higher than the centre of the groove, so that when the point of the screw is tightened into the groove it engages the top edge of the groove but not the bottom.  It thus pulls the top rim of the drum down hard against the top of the stem.  The problem is that being only a single screw it pulls the drum firmly down on one side but not the other, leaving it skew and partially obliterating the horizontal graduations on the turret below the drum.

The task was to make it level.  My first thought was to fit another two screws, so that there would be three at 120 degree spacing. The selective loosening and tightening of these should make it possible to get the drum level.  So the plan was to get two more screws and drill and tap two extra holes in the drum.  The screw is a socket head grub screw approximately 3.50mm diameter x 5.00mm long with a 90 degree point.  Screws are seldom exactly nominal diameter.  This one measured 3.43.  It could therefore have been 3.50 x 0.60 metric or 6 x 48 US.  But the pitch fitted neither.  As near as I could tell it was 56 TPI but could have been 0.50 metric.  The snag was the neither is a standard metric or US, not even a standard metric or US fine.  So it was completely non standard which meant no chance of getting a tap.

The only practical choice was to scrap the existing screw ( leave it in place but not engaging ) and drill and tap holes for three new screws of standard thread.  The thickness of the metal was such that the existing 3.50mm thread left very little metal at the sides, with the risk that the slightest error in drilling the holes would leave the walls dangerously thin.  I therefore elected to use 3.00mm metric which were available at my local engineering supplier and for which I had taps.

So far so good.  The job basically consisted of two operations, drilling and tapping the holes and pointing the screws.  On the face of it, drilling and tapping three holes in the periphery of the drum seems easy.  No great precision is needed, they don’t have to be spaced exactly 120 degrees as long as they are reasonably close ie eyeball close.   They do however need to be radial ie facing the exact centre of the drum not skew.  I set the drum up in a small machine vise mounted on the vertical slide of my lathe facing the headstock in which was fitted the drill chuck.  The fixed jaw of the machine vise was at the bottom, providing a shelf at a constant height.  I drew a circle on a piece of masking tape using the drum as a template.  Then I made three marks at the 3, 6, and 9 O’Clock positions on the circle and stuck in down on the shelf formed by the bottom jaw of the vise with the 6 O Clock mark exactly facing the drill chuck.  It was then possible to clamp the drum in the vise and adjust the cross slide

That was the easy part.  The real problem, which I hadn’t expected, was machining the points on the screws.  The smallness was the problem, how to hold them and get them on centre to machine a concentric point.  The first attempt resulted in eccentric points.  Very eccentric.  They did the job after a fashion, but it took a lot of fiddling to get the drum level.  That’s because an eccentric 90 degree point can be withdrawing from engagement even while the screw is being turned inward.  It offended my sense of quality so a better method had to be found.

Simple collet chucks are easy to make for use with a four jaw chuck, but not so easy for something as small as 3mm.  Worse, such a chuck must have a hole exactly the diameter of the work.  In this case that was 2.90mm or slightly less.  That was OK but the difficulty was slitting a 3mm hole.  Again, can be done but all things added together was getting seriously awkward.  Not difficult for a watchmaker for real messy for us ordinary mortals.  I needed something accurate that I could easily make.

The answer was found in a minaiture V block.  Why not use an ordinary V block?  Because the groove in the bottom was too big and so was the diameter of the clamp screw.  Furthermore, even a small V block is too cumbersome and the clamp rotating at high revs too much risk for my delicate knuckles.  I made my little V block from a 50mm length of 20 x 6mm bright drawn strip.  The V was cut in the 6mm edge with a slitting saw between centres and the work mounted in the machine vise on the vertical slide.  It is a small V, less than 3mm deep.

A little clamp was then made, secured to the block with two 3.50mm tapped holes.  Two bigger holes were drilled through the wide side for attaching to a sub faceplate in the 4 jaw chuck.  Oh, yeah, I forgot, also had to machine a short piece of rod to exactly same dia as screw for setting to centre.  That’s because the screw is too short to set with a DTI.  The setting rod was clamped in the V block and set to centre with the 4 jaw and DTI, then removed and the first screw clamped.  As the screws were only 6mm long ( I bought them a bit longer than the original for clamping ) they only protruded from the V block about 2mm.  It proved quite easy to machine the points.

Are they perfect ? No, not to the last few microns.  Are they good ? Yes, the points are nice, and visually dead on centre through a 10 x watchmaker’s loupe.  At any rate they work a lot better than the first lot.  The drum is now nice and level on it’s turret and is more securely fitted with three screws instead of one.

From this I learned several useful things.  First, a simple V block is good way of setting work dead on centre, or any desired amount off centre.  Second, how to make decent V blocks.  Hadn’t thought of it before because it’s not something used often.  Might be used more often now I’ve seen the usefulness.  Third, it showed yet again the sheer usefulness of a 4 jaw chuck.  Couldn’t have been done in a three jaw.  Also, the usefulness of slitting saws.  They are seldom seen in hobbyists workshops.  But in addition for cutting neat slits ( for clamping ) they will cut beautiful chamfer and cut at any desired angle.  And now they will make V blocks.

What’s a sub faceplate ?  It’s a disc, somewhat smaller than the 4 jaw chuck, that can be held in the chuck.  Usually aluminium as it’s easy to machine and it’s light which minimises the eccentric centrifugal forces that can be a problem with off centre work.  They are often called sacrificial faceplates because they can be tapped with any holes wanted to hold the work, and can be faced off any time perfect squareness to centre line is needed.  Eventually they get so full of holes or so thin they have to be scrapped.  Hence sacrificial.  The are so useful because they can be used to attach anything, and can be adjusted to centre by the 4 jaw, the 4 jaw being the vehicle that makes it possible.

Therefore, at the risk of repeating myself, if you have a lathe or intend to buy one, don’t even bother unless you are prepared to fork out for a four jaw chuck.  For sheer versatility in the range and precision of work it can do, it is of more value than all other accessories combined.  Without it you will deny yourself 90% of the possibilities of the lathe.  I am so enthusiastic about 4 jaw chucks I’m even thinking of writing a small manual about it, but don’t hold your breath it’s a lot of work and probably won’t be done.  But take my advice, don’t be without a 4 jaw!

[Originally posted to SATalkGuns -- Admin]