Refurbishing an Argentine RB - Part 15 - Yippee, it works!
Yipppeeeeeee!!!!! :dancingbanana::dancingbanana:
It works! :cheers::cheers:
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
:wave:
P.S: in the meantime, I see that Claven2 has also dealt with the cleaning question very satisfactorily.
REfurbishing an Agentine RB - Part 16 - the second firing
Having cleaned the once-fired cases, it’s time to think about the second load. What - you’ve already loaded. No matter, you neck-sized the cases - that is the most important thing. Since the cases have already been fire-formed in the chamber, they will have a better fit if they are only neck-sized. And they will last a long, long time in a BPCR if they are neck-sized and, of course, cleaned soon after firing.
Any system will give a bit under the stress of firing. In the case of the RB, any slight opening of the block under load, even though it may only be a couple of thou, will tend to form the base at a slight angle. It is generally a good idea if you mark the base of the case so that you can always insert it with the same orientation. Or always have the same letter of the name at the top, for instance. Keeping the case in the same orientation for each firing gives you the best fit and the least working of the brass.
The expansion of the case will not have provided much more volume, unless the chamber was very loose. Did any more powder go into the case, or did you keep the same load?
And you are right to avoid shooting in failing light. The sight picture, in particular that tricky judgement of the position of the top of the blade, will be affected by lighting conditions. Any halfway-usable aperture is worth a try, but that will make the sighting even more tricky in failing light. So let's hope it's a bright day for your next shoot!
As to the foresight, I have looked very closely at the photos. Maybe it is my fertile imagination, but I suspect that the sight could have a dovetail - but one running along the block, not across it! In the first picture of the block there appears to be a very slight protrusion at the rear, on the left side (towards the camera). In the second picture. there seems to be just the suggestion of a line extending down on the right side of the blade - or is that just a hair. And in the 3rd picture, I again think I see a slight protrusion on the left, towards the camera, together with a curious mark as if the blade had been filed to fit.
Please examine the blade + block with a watchmaker’s eyeglass. It could be that the blade is a kind of tríangular-cross-sectioned block set into a fore-and-aft dovetail. If so, it would be simple to drive out the old blade and file up a taller replacement oneself. Consider this as option 4), since you were asking for suggestions.
That sad object you found as option 1) looks so tatty, I would rather file up something myself.
Option 3) is making an irreversible alteration to the rifle. But some RBs did have cross-dovetailed foresight blades, so if you do as Claven2 suggests, no-one can claim “no RB was ever like that”. Not quite as that particular rifle was made, but not illegitimate for RBs in general.
Option 2) can be considered, but not as silver soldering - that requires far to high a temperature, and if the block was soldered on, it will fall off in the process!
Option 2) improved would be to cut a piece out of 1/16 or 3/32 brass or steel plate to make a blade extension. Make it with a little tang at the back, to go behind the existing blade (i.e. the tang on the breech side) and soft-solder it on. The shock on firing pushes the rifle, and thus the foresight, back against the extension piece, compressing the solder joint. It will be quite safe. In fact, on a friend's Chilean Mauser I fixed such an extension with epoxy “liquid metal” (is that what JB weld is?) and it is still there, 4 years later! And yes, he does actually use the rifle!
So there you have 2, possibly 3 options to choose from.
At the very least, you must get a flat top on that foresight blade. As it is, you are going to have more difficulty than normal with open sights in positioning that beaten-up top on any target.
And a final tip for today: One usually reads that open sights should be aimed so that the top of the blade is in line with the top of the backsight left and right of the V. That, Joel, is for beginners.
Some backsight Vs (like on the Martini-Henry) are so wide that if you try for this sight picture, the corners of the V are actually outside the target frame, making the whole exercise well-nigh impossible. But shooters at the British School of Musketry in the 19th century were taught to make height corrections by holding the blade deeper in the V, as required. If you hold the blade really deep in the V, until it is just about to disappear, you may find, as I have, that you can achieve a much more consistent POI, and, incidentally, at least partially correct for the excessively high POI that you get with the “Normal” sight picture. This is how 19th century shooters adjusted for the light and intermediate distances when only having sights crudely calibrated in 100 yards steps. And it automatically centers the blade better in the V. But it has been forgotten for so long, that it now counts as secret knowledge - so don’t tell anyone!
Good luck with the next trial! And don’t forget the pictures -including one of the muzzle (I will keep reminding you!)
Patrick
:wave: