GB2239696A - Compressed gas firearm - Google Patents

Abstract

In compressed gas firearms, an extension with a coaxial bore is provided at the end of the barrel bore, the discharge diameter e of the coaxial bore being approximately 3-5 times the diameter d of the barrel bore. The extension can be incorporated in the barrel or can be fitted in the form of a sleeve on the barrel in coaxial relationship. With suitable dimensioning of the extension, the hit pattern of compressed gas firearms of any technical design configuration is changed for the better. Various internal shapes for the coaxial bore are specified: it may include a cylindrical section 70b and/or a section 71 which enlarges conically towards the discharge mouth. <IMAGE>

Description

9 1 t 2 2!:2-3 Z-1 Gi P E, 1 C"WMSED GAS FIREARM, IN PARrICULAR A RIFLE OR

HAND GUN The invention relates to a compressed gas firearm, in particular a rifle or hand gun, comprising a barrel which has a barrel bore and in which a projectile is accelerated after actuation of a trigger system by expanding compressed gas and leaves said bore at the nuzzle thereof.

In order to achieve a high degree of precision in a compressed gas firearm, inter alia the following parameters are in-portant:

- satisfactory sighting device; - precisely manufactured barrel; - optimum nuzzle velocity; - short firing development time; - low-shake system; vibration-damping cnents; and - projectiles with close tolerances in respect of shape and weight.

What are known as diabolos of a 4.5 calibre are prescribed in the 15 rules of the M.T. as projectiles for competitions using cempressed gas firearms, and the permissible energy is restricted in various countries to 7.5 J. The maxim= nuzzle velocity is therefore laid dawn.

The length of the barrel is determined by different factors. For, on the one hand, the barrel should be as long as possible in order to be able to mount the front sighting device at a great distance from the eye of the marksman and to achieve a long target sighting line. On the other hand the optimum length of the calibrated barrel which is usually provided with grooves is restricted by the pressure energy for accelerating the projectile. Barrel length optimisation depends in particular on the mount of energy which is liberated when firing the firearm in the compressed gas system; in relation t conversion of the pressure energy into kinetic energy of the projectile, and with the endeavour to achieve a firing development time which is as short as possible, the barrel length which is most favourable from the internal Union Internationale de Tir 1 2 ballistic point of view is relatively short in the case of compressed gas firearm.

In relation to compressed gas firearm with relatively short barrel lengths, it is possible to reduce scatter phencmena in the hit pattern at the target by tapering the barrel bore in the region of the nuzzle of the barrel. That barrel configuration is relatively expensive from the technical point of view. A crable effect at a lower level of technical expenditure is achieved by the known front sight carrier tube which extends the target sighting line.

In spite of paying attention to and optimising the above-mentioned paran-ieters which determine the degree of accuracy of a cempressed gas firearm, even with the. inclusion of front sight carrier tubes for extending the sighting line, compressed gas firearm still suffer from relatively severe scatter phenomna in the hit pattern.

Taking that state of the art as his basic starting point, the inventor set himelf the object of further improving the scatter effect in the hit pattern of a compressed gas firearm, using technical means which are as simple as possible.

That object is achieved in that associated with the nuzzle of the barrel bore is a coaxial bore which extends said barrel bore and the discharge mouth of which is of a discharge diameter, the dimension of which approximately corresponds to three times to five times the diameter of the barrel bore.

It was surprisingly found that an extension of the grooved barrel exerts a positive influence on the pattern of shots if certain Mirensional relationships are observed. Amazingly good hit patterns were achieved with an extension bore which extends the barrel bore if the extension bore afforded a discharge diameter of fran 15 to 22 n-m at the end remote from the piston, for the usual projectile calibres. In accordance with the invention, it was possible for the length of the extension bore to be varied between 2.5 and 8 times the discharge 1 i 1 i 1 3 diameter of the discharge mouth, without a substantial variation in the pattern of shots.

It is in accordance with the invention for the extension bore to be disposed in a sleeve which is mounted coaxially to the barrel.

Certain configurations in respect of the internal shape of the extension or the sleeve have proven to be advantageous, for example a cylindrical extension bore which extends over the effective length thereof and the diameter of which corresponds to said discharge diameter, or an extension bore which enlarges conically from the nuzzle plane of the barrel to the discharge mouth.

Also of inventive significance are combined shapes in which the extension bore is csed of at least one section which enlarges conically in the target direction and at least one cylindrical section, the diameter of which is larger than the diameter of the barrel bore and at most as large as the discharge diameter.

Disposed at the transition from the muzzle of the barrel bore to the extension bore is an annular shoulder surface which is disposed normal to the longitudinal axis of the barrel and which is sharp-edged or which form a rounded transition at least to one of the sections of the extension bore. The annular shoulder surface may also be disposed in a blind groove which surrounds the bore of the barrel and in front of the muzzle plane in the target direction.

Providing the extension in the form of a sleeve fitted to the barrel, as referred to above, affords advantages in terms of cost as the overall length of the grooved barrel is reduced. The sleeve may also be node from a material of a different specific weight.

Overall, the hit pattern can be positively influenced by weans of the subject of the invention and furthermore the front sight can be positioned towards the target in per se known manner by weans of the sleeve.

The extension according to the invention can be used with equal 1 4 success in relation to all kinds of compressed gas firearms, irrespective of whether the weapons of that kind are rifles or handguns. In that respect it is also immaterial whether the pressure energy comes from a spring pressure system, compressed gas cartridges (for exaTple CO 2 cartridges) or a single-cylinder or multi-cylinder pump system.

Likewise the extension according to the invention can also be used in relation to compressed gas firearm with a rigid barrel or a pivoted barrel.

Pur,ther advantages, features and details of the invention will be apparent from the following description of preferred embodiments and with reference to the drawing in which:

Figure 1 is a view in longitudinal section of the free end of a rifle barrel, Figures 2 to 7 show different embodiments of the Figure 1 structure, and Figure 8 shows the free end of the rifle barrel with a sleeve fitted thereon.

Figure 1 is a view in longitudinal section through the free end of a barrel 18 with a calibrated barrel bore 19 of a diameter d of 4. 5 rrm, the barrel bore terminating at a plane M which is referred to hereinafter as the muzzle plane M of the barrel 18. Adjoining the nuzzle plane M is a coaxial extension 66 with a cylindrical extension bore 70, the discharge mouth 72 of which is of a dicayeter e. For commercially available competition diabolos 62 of a calibre d of 4.5 mm, the above- mentioned diameter e measures about 15 to 22 mm, with an effective length n of the extension bore 70 of from 2.5 to 8 times the discharge dic- ineter e. The annular shoulder surface 69 is provided as a transition between the barrel bore 19 and the extension bore 70 and is disposed at a right angle relative to the axis A of the barrel and is of a flat and therefore sharp-edged configuration, whereas in the embodiment shown in Figure 2 that transition affords a rounded annular shoulder surface 69.

1 1 Figure 3 shows an annular shoulder surface 69 which is set back behind the barrel muzzle 17 and therefore behind the muzzle plane M and thus defines a blind groove 74.

The drawing also shows different formis of extension bores, more specifically: Figure 4 shows an extension bore 70 a which enlarges conically aver the entire length n to the discharge diameter e; Figure 5 shows an extension bore 70 b which is cylindrical at the mouth end, of a length q, with a conical intermediate bore portion 71 of a length t, which is arranged upstrean of the extension bore 70b in the target direction x; Figure 6 shows an extension bore with a cylindrical intermediate bore portion 71 c which is of a larger diameter i relative to the barrel bore 19, and an adjoining conical end bore portion 70 c; and finally Figure 7 shows an extension bore with a conical transitional section 71,, between the barrel bore 19 and the cylindrical intermediate bore portion 71 c, wherein the length f thereof my be greater than the length t 1 of the transitional section 71d but shorter than the length q, of the cylindrical section 70 c of the extension bore.

As shown in Figure 8, the extension may also be in the form of a tube or sleeve 68 which is fitted coaxially on to the barrel 18 of an air rifle. The interior of the sleeve 68 corresponds to the structures shown in Figures 2 to 7, while the length of the sleeve 68 must be greater than the effective length n of its extension bore 70 or 70 a; 70 W 71; 70c# 71 c, 71d, which extends between the muzzle plane M and the discharge mouth 72.

Figure 8 further shows that the front end of the barrel 18 is provided with a chamfer 21 whereby the annular shoulder surface 69 is of an at least partially inclinedly extending configuration.

Tests were carried out with weapons of the design configuration according to the invention, which were claTp:d in position. When the specified dimensional relationships and dimensions were above or below the stated values, perceptibly worse results occurred. The best result 6 was obtained with an extension 66, 68 of an inside diameter e of 18 mm and an effective length n of 108 rffn with for exmple an air rifle in which the length of the barrel bore was so selected that the projectile leaves same as soon as the expanding gases no longer accelerate the projectile to a considerable degree.

The sleeve 68 or also the extension 66 carries a front aiming device in the form of a front sight with which there is associated a rear aiming device on the weapon.

In an embodiment which is not illustrated, the extension bores 70, 71 are of polygonal cross-section, the internal contour of which is determined by the above-specified dianp-ters d.

4 1 CLAMS -7 1. A cempressed gas firearm, in particular a rifle or hand gun, ccmprising a barrel which has a barrel bore and in which a projectile is accelerated after actuation of a trigger system by expanding conpressed gas and leaves said bore at the nuzzle thereof, characterised in that associated with the nuzzle (17) of the barrel bore (19) is a coaxial bore (70, 71) which extends said barrel bore and the discharge mouth (72) of which is of a discharge diameter (e), the dimension of which approximately corresponds to three times to five times the diameter (d) of the barrel bore.

2. A compressed gas firearm according to claim 1 characterised by a discharge diameter (e) of from 15 to 22 mm.

3. A ccmpressed gas firearm according to claim 1 or claim 2 characterised in that the spacing (n) of the discharge mouth (72) of the extension bore (70, 71) from a nuzzle plane (M) which is defined by the nuzzle (17) of the barrel (18) is from 2.5 to 8 times the discharge diameter (e) of the discharge mouth.

4. A compressed gas firearm according to one of claim 1 to 3 characterised in that the extension bore (70, 71) has a discharge diameter (e) of about 18 nm and an effective length (n) of about 108 mm.

5. A ressed gas firearm according to one of claims 1 to 4 characterised in that the extension bore (70) is cylindrical and its diameter is the discharge diameter (e).

6. A compressed gas firearm according to one of claims 1 to 4 characterised in that the extension bore (70 a) enlarges conically approximately from the nuzzle plane (M) of the barrel (18) to the discharge mouth (72).

1<3 7. A cempressed gas firearm according to one of claim 1 to 4 characterised in that the extension bore is cariposed of at least one section (71, 71d, 70c) which enlarges conically in the target direction (x) and at least one cylindrical section (71 c), the diameter (i) of which is larger than the diameter (d) of the barrel bore (19) and at most as large as the discharge diamter (e).

8. A corrpressed gas firearm according to at least one of claims 1 to 7 characterised by a flat annular shoulder surface (69) as the transition from the muzzle (17) of the barrel bore (19) to the extension bore (70, 71).

9. A ccmpressed gas firearm according to claim 8 characterised in that the annular shoulder surface (69) form a rounded transition at least to one of the sections of the extension bore (70, 71) (Figures 4 and 5).

10. A ccrnpressed gas firearm according to claim 8 characterised in that the annular shoulder surface (69) is disposed in a blind groove (74) surrounding the barrel bore (19) and in front of the nuzzle plane (M) in the target direction (x).

11. A ressed gas firearm according to at least one of claims 1 to 10 characterised in that an extension which contains the extension bore (70, 71) is secured to the barrel (18) coaxially and releagably therefrem.

12. A ccnipressed gas firearm according to claim 8 or claim. 11 characterised in that the extension bore (70, 71) is provided in a sleeve (68) connected to the barrel (18) and the transition between the nuzzle (17) of the barrel (18) and the extension bore defines the annular shoulder surface (69).

i 1 1 R 13. A ressed gas firearm according to claim 12 characterised in that the annular shoulder surface (69) as the transition between the muzzle (17) of the barrel (18) and the extension bore is fo of an at least partially inclinedly extending configuration by virtue of a chamfer at the front end of the barrel (18).

14. A ressed gas firearm according to at least one of claims 1 to 13 characterised in that the cross-section of the extension bore (70, 71) is of a polygonal and in particular hexagonal configuration.

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