Muchas gracias Cooper y Viti. La verdad es una pena, tiene buena pinta esta superpuesta.
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VERDADERAMENTE UNA NUEVA SUPERPUESTA.[Tienes que estar registrado y conectado para ver este vínculo]
The word new has been a little overused by marketing people, but this shotgun deserves the title. The creation of a highly qualified engineer, the new Lastra (the name of its inventor) offers a number of features that put this shotgun in a class of its own and might just make it a game changer.
PERFIL ULTRA BAJO.[Tienes que estar registrado y conectado para ver este vínculo]
Lowering the profile has been the holy grail of OU design since the first commercially viable guns hit the market. English makers Boss and Woodward are usually credited with being the first to conceive of splitting the cross pin, turning it into bifurcated pins, and moving the lock up to the breech face and not under the barrels. Credit is also due to that most neglected genious, William Baker, who employed trapezoid shoulders and recesses to achieve the same aim, to lower the profile of the OU. The trapezoid shoulders later became a Beretta standby.
To quantify the term, low guns today have a profile that measures about 63 millimeters from the bottom of the action to the top of the breech, where the barrels join the action. The Swedish Caprinus is the lowest profile I have ever measure, at 56 millimeters.
LA ESCOPETA DE RAFAEL LASTRA ES INCLUSO MÁS BAJA.[Tienes que estar registrado y conectado para ver este vínculo]
Inventor Rafael Lastra states:
«Priority 1 for this design was to get the action height down to the absolute minimum. This first one is in 28 gauge and is only 47mm high, 20 = 50mm, 16 = 52mm and the 12 comes in at 54.5mm, which I believe are the lowest on the market.»
To get these measurements in some perspective it is useful to compare them to side-by-side dimensions. My Cogswell and Harrison 410 has a breech depth of 41 millimeters, an Italian best boxlock 55 millimeters and a Westley Richards Droplock 54 millimeters. These are all side by sides. A 20 gauge OU Citori in my rack measures 63 millimeters. My experimental 28 gauge side by side tops 49 millimeters.
CONSIGUE MAYOR RESISTENCIA.[Tienes que estar registrado y conectado para ver este vínculo]
While losing height, the Lastra gains strength. The bifurcated pins on which the barrels turn are large diameter semi circular trunnions. The barrel hooks do not ancircle the underside of the trunnions, this saving on action depth, while gaining in strength.
Large diameter trunnions are rare. The Caprinus has them but their diameter is so large as not to count as trunnions, they are more like raceways. In the Lastra they are smaller, and I am hazarding the guess that they are easier on the assembly and disassembly of the gun.
A large measure of the strength of any OU comes from the lock up between barrels and action. The low Boss action has side recesses on the barrels which mate with corresponding lugs on the insides of the action. Most high end OUs employ this system. So does the Lastra design, with one subtle difference: the arcs are not concentric, so the lugs and recesses come into full contact only when the gun is closed. As soon as the barrels begin to move, as when the gun is being opened, the contact is broken, thus minimising wear and opening effort.[Tienes que estar registrado y conectado para ver este vínculo]
The opening of the gun is facilitated by another design feature: the barrels move about 20 per cent of their arc before they start the cocking process of the locs. At that point in their travel they offer a more favorable hold, greater mechanical advantage and leverage for the left hand to cock the gun. That this was analysed and provision made in the design is indicative of the depth of thought that went into this OU.
Added strength is also derived from the metallurgy of this gun. The steel used is the Boehler W400 VMR, an «awesome» steel as Rafael Lastra describes it, offering great fracture resistance and compressive strength.
PERCUSION DIRECTA.[Tienes que estar registrado y conectado para ver este vínculo]
Over unders have angled firing pins. The exceptions are few, mostly striker fired designs and some old Nittler designed 101s and Citoris. Angled pins are not the most reliable ingnition system.
Rafael Lastra has designed a lock which delivers a direct strike to the firing pins which in turn are at right angles to the cartridge head. To achieve this the design has one pin in the orthodox, «upright» position and the other pivoting from the top, a sort of upside down lock.
The innovation on the lock goes further. The single trigger selector works in a fore and aft motion not side to side, while it is incorporated in the safety button. Not having direct contact with the gun I cannot tell how it feels, but judging by the metal finish quality evident in the photos, I would speculate it works well.
The whole lock, including the single trigger and safety are housed in a compact casette-like unit which has just six transverse pins. A traditional sidelock has seven pins per side, with all that this entails in fitting, regulating and cost.
The Lastra will be offered in a hand detachable version and later as a full sidelock. However, the sidelock will retain the direct line relationship between hammers and firing pins. One lock will in fact have an upside down hammer to do just this!
FORMAS Y PERFILES.[Tienes que estar registrado y conectado para ver este vínculo]
Rafael Lastra intends to offer his OU in all popular gauges and in two basic forms, what he calls a heavy square action and a rounded bar version. There will also be the innovative sidelock mentioned above.
Personally I like the sweeping lines of this action. To my eye it does not look at all square. The bolster especially, starting from the shell head and embracing the action sides gives the gun a dramatic, flowing line that is very pleasing. That sweeping bolster in a round bodied action must be a sight to behold!
The graceful lines are evident in the whole and not just in parts. The low profile, the raked forend iron, the alternation of curves and planes give this OU a unique look. Modern yet not at all alien. The shapes are such that it really does not need any engraving. It is a beautiful object as it is.
PROPÓSITO.[Tienes que estar registrado y conectado para ver este vínculo]
Why design yet one more Over Under?
Rafael Lastra states his design objectives: «The whole point of the design is to have an over-under that handles as well as a side-by-side and specifically oriented for the game fields where instinctive shooting is the name of the game.»
Given the ultra low profile and the thought devoted to ergonomics I think the design objectives are being met. Persoanlly speaking I am impatient to see a Lastra OU up close and personal. If it has the handling of a classic SXS combined with the low profile it should offer what some high end OUs lack, liveliness. The low profile also promise low felt recoil which is always a welcome feature.
When will it appear? The first one should be ready by the end of this year (2014). Soon after the inventor intends to go into full production. When that happens my guess is that big names in the upper reaches of the OU world will have plenty to worry about. It is about time!
Rafael Lastra is a US trained engineer, specialising in control system design. Gun design is his passion and he has come to a point in his career that he can devote his full time to his passion. The Over Under is his first venture. If this refined OU counts as his «baby steps» then we can definitely expect more, lots more, from this designer.