Bsa Trigger Assembly Mk 111

38. Trigger adjusting screw

39. Trigger stop screw

40. Locking screw (2)

41. Hammer

42. Hammer bush t

43. Hammer spring

44. Ejector spring

45. Ejector lever spring

46. Ejector release lever

47. Ejector lever axis pin

48. Ejector

49. Sear spacing collar (2)

50. Sear

51. Butt

♦Factory assembled to insure precision accuracy. Do not disassemble.

tPermanent factory assembled.

JOne each functions as axis for breechblock, cocking lever, and ejector.


The BSA Martini-International Mk III match rifle was first made available for general sale in May 1960. Chambered for the cal. .22 long rifle cartridge, the Mk III rifle is the latest of a long series of Martini-action precision target rifles made by the English firm of BSA Guns Ltd. The Mk III rifle replaced the BSA Mk II model introduced after World War II.

The basic action design of this rifle is very old and stems from U. S. Patent No. 35,947 granted in 1862 to H. L. Peabody of Boston, Mass. The Peabody patent featured a falling breechblock hinged at the rear end. The patent covered both hammerless and exposed hammer ignition systems, but the latter style was selected for production here. The Peabody rifle was tested by U. S. Ordnance boards, but failed of adoption. However, a considerable quantity of Peabody military rifles were manufactured by the Providence Tool Co., for various foreign countries, including Canada and Turkey.

In 1867 the Swiss Republic adopted the Peabody rifle, and during the trials, a Swiss inventor, Friedrich Martini, developed a hammerless modification of the rifle, or improvement of the action, in which the striker was driven by an internal coil spring.

The English government subsequently adopted a service rifle with the Peabody-Martini action, and the barrel was rifled according to the plan of Alexander Henry. The rifle was then arbitrarily called the Martini-Henry, the name of the original inventor being ignored.

The Peabody-Martini action is particularly suitable for rimfire target rifles as the compact design provides solid support of the cartridge and very fast lock time. In the current Mk III model the entire action mechanism can be easily withdrawn from the receiver for routine inspection or cleaning. The full-floated barrel has a strikingly long 3" bearing in the receiver which enhances rigidity of the barrel-receiver assembly. The under-lever loading principle and feed groove in the breechblock permit convenient loading of the chamber in the prone position without taking the rifle from the shoulder. The trigger is fully adjustable for weight of pull and overtravel. The stock assembly of French walnut, is of Monte Carlo pattern and is based on the design of A1 Freeland, a leading American smallbore rifleman. The Mk III is optionally available in both left-hand and right-hand action styles.

1 Disassemble BSA Mk III by first L pressing cocking lever (28) to full ejection position and unscrewing guard keeper screw (6). Trigger frame (27) carrying complete mechanism may be removed by exerting downward pressure on trigger guard. Place a 1" length of 3/16" drill rod against ejector spring (44) and apply machinists clamp as shown using block of soft wood against bottom surface of trigger frame. This relieves tension on ejector (48) and ejector lever axis pin (47). Drift out this pin and ejector axis pin (29) and remove ejector, ejector spring, ejector release lever (46), and ejector lever spring (45) being careful not to lose the latter


2 Drift out breechblock axis pin (29) and with breechblock (34) still in ejection position, pull breechblock firmly forward, upward, and away. This requires some tricky manipulation to get the feel in order to release breechblock from tumbler (30) and cocking lever

Wood Cocking Lever

3 Next—carefully drift out hammer axis pin (36, arrow) and lift out hammer (41) with hammer bush (42) and hammer spring (43) attached

Gun Turned Sideways

4 Drift out cocking lever axis pin (29) and lift out tumbler (30) and remove cocking lever through top of trigger frame. Cocking lever must be turned sideways when bringing handle portion through trigger frame

5 Drift out sear axis pin (36) and axis pin, small (36, upper arrows) and remove sear (50) and sear spacing collars (49). Drift out trigger axis pin (36, lower arrow) and lift trigger (35) out from top of frame being careful not to lose trigger spring (37) which will drop out when frame is turned upside down

Drop Hammer Mechanism

6 Using a wide-blade screwdriver, unscrew striker retaining screw (31) and tap out striker spring (32) and striker (33). Reassemble mechanism in reverse. When hammer has been replaced, hammer spring prongs can be engaged to sear pinions by inserting small screwdriver under each side of hammer axis pin and gently prying spring prongs upward and over sear pinions H

M16 Rifle Hammer Mechanism

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