Argentino M1879 Rolling Block. Is it worth restoring?

[Patrick Chadwick]

Yipppeeeeeee!!!!!

It works!

And for a very first shoot that is quite satisfactory! It is in fact, very promising.
There is a lot to be learnt from the pictures of the target.

1) The shots are not keyholing
So the bullets are coming out straight enough and flying true. Any wear in the muzzle is not so strongly asymmetrical that it makes the bullets tumble.

2) They are all on the paper.
So you do not have a “blunderbuss muzzle.

3) After the fouling shot, you had a better than 4”group (assuming that the target is divided into 1” squares). The load is indeed a PDG first approximation.

These three points indicate that, for the moment at least, we do not need to worry about the muzzle. It could surely be improved, but there are other, simpler things that need to be attended to first, before you undertake what really is an irreversible (if minor) alteration to the rifle.

The very first aspect for improvement is “the vision thing”.

4) Take a look at your group, including the fouling shot. Apart from one shot out to the right, the horizontal spread is hardly 1”. That would be good with a modern rifle using open sights. Are those protective shooting glasses you are wearing? If so, Caleb should have worn them as well. Or are they glasses for driving? In which case, they are probably optimized for a distance of about 25 yards. Do you find it difficult to see the dashboard when driving? Then you can probably see the target well enough, but the foresight is a fuzzy blob and the backsight is a thing of the imagination.

Open sights were made for teenage conscripts, not for us more advanced teenagers (5th time around in my case). Since open sights are symmetrical about the vertical axis, one can center the sight picture well enough horizontally, but the vertical position is a matter of guesswork that varies with the light. This is one possible reason why the group from Caleb has a higher POI than yours - he is seeing the foresight blade sharper.

Age, lack of visual accommodation, and maybe a touch of astigmatism, all make it well-nigh impossible to see backsight, foresight and target all clearly at the same time. The only way to improve this is to reduce the aperture. If you stop down the optical aperture, you will instantly see an improvement in the sight picture.

Since the RB does not have provision for fitting a peep-sight, the answer is to wear glasses that have an aperture-adjusting device attached. I have an iris that can be attached to my driving glasses by a sucker pad, but for serious shooting I use shooting glasses with an iris on an adjustable fixture. Regardless of what kind of gun you are shooting, for any non-dynamic shooting this is the very first aspect to be improved before worrying about sights.

For a quick-and-dirty solution to check whether an aperture would help, you can punch out a hole in a piece of thin plastic, using a leather punch set for the smallest hole, and hold it over your glasses while aiming.

Get the sight picture improved, and the group will tighten up somewhat - maybe even a lot. But there is no point in trying to improve the rifle if any improvements are swamped by a poor sight picture.

When you have dealt with point 4), we can move on.

5) POI - point of impact.
Take a look at the side of the backsight block. The lowest marked setting is probably 100 meters - nearly twice as far as you were shooting - and the foresight blade is also probably worn down a bit. I imagine you were aiming at the center of the red square, or on the bottom line.

The fix here is to get a high foresight blade for a Mauser K98 - they go up to 8 or 9 mm, and will be easier to find than RB spares. The original RB blade should be driven out (left to right, I think) with a brass drift, and kept safe. The Mauser blade can be fitted with maybe a touch of filing or peening of the dovetail. Do not, of course, file or peen the foresight block on the RB! But it might be a good idea to scribe a witness mark on the foresight block before removing the original blade, as that makes it easier to set the new blade in the correct position

This should provide you with a POI that is much better centered for height. Do not immediately file the new blade down so that the POI is dead on at 100 meters - it is very load-sensitive with BP ballistics, and you do not want to be restricted to only shooting at 100 meters and above. Remember, you can always file it off, but filing it back on again is a bit more awkward! It is sufficient that the sight slider is off the bottom of the ladder, so that you have room for adjustment.

6) Load.
As far as can be seen, looking at the grouping and pending the improvements suggested above, the load is OK. You have observed how the fouling shot is higher than following shots. As I wrote some while ago, only the first shot on a BPCR rifle is a clean-bore shot. Everything that follows is a "crud-riding" shot, unless you clean diligently after every shot, which is a) very tedious, and b) usually disallowed in military rifle competition.

Approximately, the lube in the bullet grooves lubricates the bullet, providing a kind of hydraulic seal as it moves down the barrel, which is why the bullet can ride over those worrying rust spots you saw some way down the barrel without a ballistic disaster.
The lube in the case is behind the bullet and can therefore not lubricate it, but it is the major factor in preventing the fouling from becoming hard-baked in the bore. If you were able to shoot all 20 shots without it becoming difficult to insert the case into the chamber, then it is adequate, as that would last out an entire competition target of 15 shots plus fouling shot plus sighters (if allowed). Too little lube would also show up as successive shots impacting lower and lower on the target.

You mentioned in a recent post, that it appeared feasible to seat the bullet out even longer than at present. Think carefully about that. You might then find that after a few shots the bullet comes up against fouling in the throat, making it difficult to load the cartridge, since a Rolling Block has no camming action when loading. You would also be exposing the second grease groove to possible dirt. And the bullet would only be held in the case by three thin bands at the back. So even if the throat permits it, you would not be able to go further than that, as two bands really would be inadequate for bullet seating and case expansion to seal the chamber. This would show up as combustion deposits around the neck of the case - not good for loading subsequent cartridges - or indeed, for the chamber.

7) Cleaning.
To what jmoore already wrote, I would merely like to add that you need a small stiff brush to scrub out the inside of the case when cleaning the cartridge cases. This is much more important than getting a nice shine on the outside in a tumbler. The tumbler will not do much, if anything, for the inside of the case. But the combustion deposits from inside the case will soon thoroughly contaminate the tumbler granulate!
BTW, if you would like to really appreciate why cleaning s so important, take a freshly fired case and leave it uncleaned for a week or two. Then look inside - you will be shocked at the bright-green verdigris that has appeared!

Please consider points 1) to 5) and write back - I am still waiting for a couple of good photos of the muzzle!

Patrick


P.S: in the meantime, I see that Claven2 has also dealt with the cleaning question very satisfactorily.