US2531421A - Adjustable rear sight for firearms - Google Patents

Description

Nov. 28, 1950 J. c. GARAND ADJUSTABLE REAR SIGHT FOR FIREARMS Filed June 50, 1949 m Wd Qn m n n n n E TT.,

Patented Nov. 28, 1950 ADJUSTABLE REAR SIGHT FOR FIREARMS John C. Garand, Springfield, Mass., assignor to the United States of America as represented by the Secretary of War Application June 30, 1949, Serial No. 102,187

8 Claims. (Cl. {i3-55) (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) l` The invention described in the specification and claims may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

l This invention relates to firearm sights and is directed more particularly to a rear sight having novel means for effecting vertical and lateral zeroing adjustments and having means for compensating for the drift of a iirearm projectile.

Firearm barrels are usually rifled in order to impart a rotary spin to the projectile and thereby prevent any deviation from a true line of flight. However, in long range ring, the spin of the projectile causes an appreciable amount of drift from its true course and hence detracts from the desired optimum accuracy. Heretofore, very little or no attempt has been made to incorporate automatic means in a rear sight structure for the purpose of compensating for the appreciable drift of a long range projectile.

Accordingly, it is an object of this invention to provide an improvedl rear sight structure for a firearm wherein lateral adjustment of the sighting member to compensate for drift of the projectile is automatically accomplished simultaneously with any change in vertical adjustment for range.

When mounting a rear sight to a firearm, it is necessary to align the line of sight With the line of re of the weapon. Since each firearm has varying inherent characteristics which affect the line of flight of the projectile, it is obvious that the means for adjusting the sight to the lirearm, or as is referred to in the art, zeroing in of the firearm sight must be simple in structure and be capable of quick accurate setting. Furthermore, such setting of the rear sight should not be subject to involuntary change due to the shock and vibration of firearm operation.

Accordingly, it is a further object of this invention to provide in a firearm rear sight, simple and accurate means for adjusting the horizontal and vertical position of a, sighting member so that the line of sight thereof will correspond with the-line of fire of the weapon at any distance desired.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a, description of a preferred embodiment as sho-wn in the accompanying drawings in which:

, Fig. 1 is a rear elevational view of the rear sight of this invention.

Fig. 2 is an exploded view showing the Various parts which constitute the sight.

Fig. 3 is a side elevational view, partly in cross section, of the assembled sight.

Fig. 4 is a fragmentary side view showing in cross section the means for elevating or depressing the sighting member.

Fig. 5 is a front elevational view of the sighting member.

Fig. 6 is a rear elevational view of the sight showing two different positions of the sighting member.

Fig. 'l is a perspective View of the lock washer member.

As best shown in Fig. 2, the rear sight of this invention essentially comprises a sighting -member 5 adjustably mounted in a base member 6, and a rotatable cylindrical sleeve member 'l for eiecting the Vertical and the corresponding automatic lateral movement of sighting member 5 relative to base member 6 in a manner to be explained.

The firearm to which the sight of this invention is to be mounted should include an upwardly projecting portion 8 designed to serve as a mounting block. A transverse hole 9 in block 8 is arranged to Xedly receive a split bushing Ill which in turn rotatably receives a, second split bushing I I. The ends of the latter bushing are arranged to protrude from either side of block 8 and xedly engage a pair of downwardly extending spaced apart ears I2 on a base member 6. As a result of such construction, base member 6 and consequently the entire sight is pivotally mounted to the rearm. Extending upwardly from base 6 and preferably integral therewith is a hollow cylindrical body I3 having a, longitudinal slot I4 formed therein.

A laterally projecting lug I5 is formed at the lower end of sighting member 5 and is arranged to slidably engage in slot I4 and protrude therefrom when sighting member 5 is inserted within cylindrical body I3. The sides of sighting member 5 are tapered along the central portion thereof as best shown at I6 in Fig. 5 for a purpose to appear later. The upper end of member 5 terminates in a conventional peep I'l having a roughened area I8 for the purpose of dispersing any light rays falling thereon and thereby preventing any glare against the sighting eye of the operator.

An annular groove I9 is provided at the top of cylindrical body I3 about the outer periphery thereof and is adapted to receive a resilient lock washer 20. As shown in Fig. 7, lock washer 20 is preferably formed in the shape of a horseshoe and lis provided with an upwardly extending right :ist ,is our angled portion 2| by means of which washer 20 can be forced into engagement with groove I9 or removed therefrom. Rotation of washer 20 relative to body I3 is prevented by a key 22 which extends into slot I4 when washer 2Il is fully engaged in groove I9.

Cylindrical sleeve 1 is provided with a helical groove 23 cut into the inner periphery thereof and is arranged to t about cylindrical body vI3 so that lug I5 on sighting member 5 engages in helical groove 23. The upper wall surface of groove 23 is furnished with a plurality of teeth 24 as shown in Fig. 4 and the top of lug I5 is correspondingly shaped to sequentially engage with teeth 24. The outer periphery of sleeve 1 is knurled as shown at 25 in Fig. 1 to facilitate manual rotation thereof. The lower portion of sleeve 1 is provided with indicia numerals 26 engraved or otherwise formed about the outer periphery thereof. An index line 21 on base member 6 provides a reference mark for indicating in conjunction with numerals 26 the range at which the firearm is to be operated.

' A coil spring 28 seats in a hollow body portion 29 of sighting member 5. A second coil spring 30 of greater diameter than spring 28 and appreciably shorter in length is arranged to surround the lower end portion thereof and seat within a counterbore 4I formed in the lower portion of cylindrical body I3. Springs 28 and 3l) are compressed and retained in place by a head 3| of plunger 32. Consequently spring 28 urges sighting member 5 upwardly while at the same time spring 3|! urges plunger 32 downwardly.

As shown in Figs. 2 and 3, plunger head 3| is arranged to slidably fit in hollow body portion I3 of base member 6. A key member 33 on head 3| engages a suitable slot 34 in body I3 to prevent rotation of plunger 32 therein. The bottom of head 3| terminates in a diametrical rib portion 35 having opposite sloping sides 36. The firearm mounting block 8 is also provided with at least two radially disposed notches 31 and 38 formed to receive rib portion 35 of plunger head 3|. The uppermost notch 31 retains sighting member 5 in an upright sighting position, while the lowermost notch 38 holds member 5 in a folded position. As will be noted in Fig. 3, only one of the sloping sides of rib portion 35 contacts the correspondingly sloped side of notch 31. Since the underside of base member 6 is also in contact with the top surface of block 8, sight member 5 is thereby retained in an upright sighting position wherein any accidental rocking due to backlash is prevented by the action of springs 28 and 30.

However, sighting member 5 can be readily folded to a stowed position by merely pushing thereon in the proper direction. Plunger head 3| will thereby be cammed out of notch 31 and allow base member l6 to bevpivoted to the folded position. When rib portion 35 is aligned with notch 38, the urging of springs 28 and 30 will cause plunger head 3| to engage notch 38 in a manner similar to that described for the upright position.

vA plurality of washers 39 are provided for insertion between the bottom of sleeve member 1 and base member G and also between the top of sleeve member 1 and lock washer 20. Similar washers 48 are also provided for insertion between either side of mounting block 8 and the corresponding ears I2 of base member 6. Washers 39 and 4|) canl each be of a different known thickness or can all be equal. However, the preferred arrangement as shown in Figs. l and 3,

provides for one relatively thick washer and ve equal thinner washers, the total thickness of the grouped thin washers being equivalent to the thickness of the single washer. The interchanging of washers 39 relocates the position of the sight in elevation while similar manipulation of washers 40 changes the lateral position of the sight. Thus there is here provided simple yet accurate and secure means for readily adjusting the rear sight of this invention so that its line of sight and the line of fire of the weapon correspond at any distance desired.

When the sight has been zeroed with respect to the firearm in the manner described above, adjustment of sighting member 5 for range can be made when required. As sleeve member 1 is rotated, lug I5 on sighting member 5 sequentially engages teeth 24 in helical groove 23 thereby producing audible clicking sounds. Each click preferably corresponds to two minutes ofl elevation and therefore provides a positive means for adjusting the sight to a desired range without the necessity for looking at indicia numerals 261 Such a feature is particularly advantageous when ring at night. The helical path of groove 23 causes sighting member 5 to be raised or lowered depending on the direction in which sleeve member 1 is rotated. If desired, sight member 5 can be raised or lowered without producing any audible clicks by merely pressing down on member 5 while sleeve member 1 is being rotated. As a result, coil spring 28 is compressed and allows lug I5 to disengage from teeth 24. However, sight member 5 will still move vertically since the bottom of lug I5 will contact the lower wall surface of groove 23 and follow the helical contour thereof as sleeve member 1 is being rotated. It will be appreciated that such construction allows the sight to be silently adjusted for range without the possibility of betraying the location of the operator to any nearby hidden enemy.

Since lug I5 extends outwardly to the left as shown in Fig. 1 and is engaged with teeth 24, the upward thrust of spring 28 produces a tilting movement of sighting member 5 about the point of Contact of lug I5 with teeth 24 which is, of course, limited by the clearance between the outer periphery of tapered portion I6 and the inner wall of cylindrical body I3. However, due to taper portion I6 of sighting member 5, it can be seen that any increase in elevation thereof will result in greater clearance between the two members and consequently permit more tilting of sighting member 5. Tapered portion I6 of sighting member 5 is specifically designed to produce sufficient lateral movement of peep I1 to compensate for the drift of a projectile in accordance with the range at which the target is located.

Thus, the sight of this invention is arranged to automatically position the sighting member thereof so as to provide for the drift of aprojectile fired from the weapon on which the sight is mounted. Manual adjustment of the sight in elevation simultaneously produces the lateral movement required' at the particular range selected.

I claim:

1. In an adjustable rear sight for a firearm, a base member mounted on a firearm, a sighting member vertically movable within said base member, ,a rotatable sleeve member carried by said base member, a plurality of teeth helically disposed within said sleeve member, and springbiased detentl means on said sighting member arranged to sequentially engage with said teeth to position said sighting member relative to said base member when said sleeve member is rotated.

2. In an adjustable rear sight for a firearm, a base member pivotally mounted on a firearm, said base member having a hollow cylindrical body portion, a sighting member vertically movable within said body portion, a rotatable sleeve memrber carried by said base member and arranged to surround said cylindrical body portion, a plurality of teeth helically disposed in the inner wall periphery' of said sleeve member, detent means on said sighting member arranged to sequentially engage with said teeth to position said sighting member relative to said base member when said sleeve member is rotated, and spring means arranged to bias said sighting member and thereby said detent means upwardly into yielding engagement with said teeth in said sleeve member.

3. In an adjustable rear sight for a iirearm having a mounting block thereon, a base member, means including an inner and outer split bushing for pivotally securing said base member to a firearm mounting block, said base member having a bore therethrough and a hollow upstanding cylindrical body portion in axial alignment with said bore, said body portion having a vertical slot therein, a sighting member vertically movable within said cylindrical body portion and having a laterally extending lug slidably engaged in said vertical slot, key means for retaining said sighting member in said body portion, a rotatable sleeve member surrounding said cylindrical body portion, said sleeve member having a helical groove cut into the inner periphery thereof, a plurality of teeth disposed along the upper wall surface of said groove, said sighting member lug shaped to sequentially engage with said teeth to position said sighting member relative to said base member when said sleeve member is rotated, spring means seated within said sighting member, and retaining means insertable into said base member for compressing said spring means whereby said sighting member is urged upwardly for yieldingly engaging said lug with said helically disposed teeth.

4. In an adjustable rear sight for a iirearm, the combination of, a mounting block extending upwardly from a rearm and having a pair of spaced apart grooves, a hollow base member having a counterbored portion at the bottom thereof, means including an inner and outer split bushing for pivotally securing said base member to said firearm mounting block, a sighting member vertically movable within said base member, Y

a sleeve member surrounding said base member, means for imparting vertical movement to said sighting member relative to said base member when said sleeve member is rotated, a plunger having a circular head portion insertable into said counterbored portion of said base member and having a shank portion extending into said sighting member, and spring means disposed between said sighting member and said plunger head portion for exerting an upward bias on said sighting member, all adapted and arranged whereby said plunger yieldingly mates with either of said mounting block grooves whereby the sight is maintained in either an upright sighting position or in a stowed non-operating position.

5. The combination defined in claim 4 and including, a truncated diametrical rib on said plunger head portion, said rib and said mounting block grooves having conversely sloping sides,

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and spring means disposed in said counterbored portion of said base member in abutting relationship with said plunger head portion whereby one of said sloping sides of said truncated rib resiliently contacts said corresponding opposite sloped side of each of said mounting block grooves, said mounting block arranged to contact the bottom of said base member prior to bottoming of said rib in the uppermost of said grooves thereby assuring a fixed upright position for the sight.

6. In an adjustable rear sight for a firearm, a base member pivotally mounted on a iirearm, said base member having a hollow cylindrical body portion, a sighting member vertically movable within said cylindrical body portion and having a tapered outer periphery, a sleeve member surrounding said base member, means for imparting vertical movement to said sighting member relative to said base member when said sleeve member is rotated, spring means arranged to exert an upward thrust on said sighting member, and means in said sleeve member for arresting said upward thrust of said sighting member whereby the latter member is tilted against the interior wall surface in said body portion of said base member thereby producing suicient lateral movement to compensate for the drift of a projectile fired from the firearm.

7. In an adjustable rear sight for a rearm, a base member pivotally mounted on a rearm and having a hollow cylindrical body portion, said body portion having a vertical slot therein, a sighting member having a peep sight portion and a tapered body portion, said sighting member arranged for vertical movement in said hollow cylindrical body portion and having an outwardly extending lug slidably engaging in said slot, a rotatable sleeve member surrounding said body portion of said base member, said sleeve member having a helical groove cut into the inner periphery thereof, a plurality of teeth disposed along the upper wall surface of said groove, detent means on said sighting member lug arranged to sequentially engage with said teeth and thereby impart vertical movement to said sighting member relative to said base member when said sleeve member is rotated, and spring means disposed within said tapered body portion, all adapted and arranged whereby said peep sight portion of said sighting member is tilted about said detent means as a fulcrum in order to provide sufficient lateral movement to compensate for the drift of a projectile discharged from the rearm, the taper of said sighting member body portion arranged to increase said lateral movement as said sighting member is moved upwardly.

8. In an adjustable rear sight for a iirearm having a mounting block thereon, a base member having a pair of downwardly depending ears arranged to straddle a rearm mounting block and be journaled thereto, rst interchangeable washer means positioned between each of said ears and the adjacent side of said mounting block, said base member having a hollow upstanding cylindrical body portion, a sighting member vertically movable within said body portion, a lock washer keyed to the upper end of said body portion for retaining said sighting member therein, a rotatable sleeve member surrounding said body portion, and second interchangeable washer means positioned between said base member and the underside of said sleeve member and also between said lock washer 7 8 and the top of said sleeve member, al1 adapted REFERENCES CITED "and-arranged whereby addition or subtraction of The following references are of record in the said first interchangeable washer means from one location to the other .repositions the sight me of uns patent laterally with respect to the mounting block on 5 UNITED STATES PATENTS the rearm and the addition or subtraction 0f Number Name Date said second interchangeable washer means from 368,593 Lyman Aug. 23, 1887 one location to the other repOSbOnS Said Sight- 846,637 Wilcox Mar. 12, 1907 'ing member vertically with respect to said base 846,633 Windridge Man 12y 1907 member. 10 1,057,048 Farrow Mar. 25, 1913 JOI-IN C. GARAND.

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