[MG Note: In Part 1 we discussed the need for blank fire adapters (BFA) on the Commonwealth rifles, the necessity for interoperability of the BFA's on those rifles, and form differences between the Australian, British, and Canadian BFA's. We introduced the three kinds of Australian-produced BFA and resume the story here, beginning with the F1 BFA. All dimensions cited are in inches and are approximates.]
The basic F1 BFA is a double diameter sleeve with a large outside diameter (O.D.) of 1.38 inches, a small O.D. of 0.83 inches, a body length of 4.60 inches, and and overall length (OAL) of 5.33 inches with the knurled restrictor knob installed. The BFA body large O.D. has a notch for the flash eliminator bayonet lug and a pivoting latch; the small O.D. is threaded internally and has notches cut in the end to act as a lock for the detent spring of the knurled restrictor knob. The restrictor knob is about 1.42 inches in diameter and 0.50 inches thick with a threaded end. The threaded end is bored out to accept an orifice or restrictor tube. The small hole in the end of the tube allows part of the gas generated by the blank to bleed off while trapping enough gas to work the action of the SLR or AR. A stamped steel detent spring is riveted to the knob and locks the restrictor to the BFA body when installed.
Early production F1 BFA's were painted chrome yellow. Later, the specification was changed to insignia red. Red painted BFA's include: late Australian F1 BFA's supplied to the Australian Defence Forces; refurbished older F1 BFA's reissued to the ADF; and BFA's sold to New Zealand for their L1A1 and L2A1 rifles.
Above: Two versions of the Australian F1 BFA showing slight differences in manufacture. The color indicates early production BFA's. (Photo: Kevin Adams)
Below: The BFA's suppled to New Zealand were painted red. Late and refurbished Australian BFA's were also painted red due to a change in the procurement specification, although the design remained the same. Note that the pivoting latch is partially open. (Photo: The Dealer Warehouse)
To install, the restrictor is removed and the latch opened. The BFA slides over the flash eliminator so that the bayonet lug is against the top of the notch in the large O.D. of the BFA. The pivoting latch is then closed behind the bayonet lug. The threaded restrictor's tube is inserted into the flash eliminator and the restrictor knob screwed into the small I.D. of the BFA body until it stops. The spring detent snaps into one of the notches in the end of the BFA body and locks the restrictor in place. The rifle is now ready to fire blanks. If the rifle does not cycle reliably with the BFA installed, it may be necessary to adjust the nut in back of the gas block to trap more propellant gas to work the rifle's action. Removal is the reverse of installation. The gas block's gas adjusting nut should be returned to its original position for firing of conventional Ball ammunition.
The F1 (Special) BFA for the L1A1-F1 built for Papua New Guinea and Hong Kong used a shortened restrictor orifice tube to compensate for the redesigned and shortened flash eliminator of this model. The body of the BFA remained yellow but the shortened restrictor was painted red. Troops could instantly tell the difference between the BFA for the F1 rifle and that of the standard L1A1 rifle.
Above: The Australian F1 (Special) BFA as suppled to Papua New Guinea and Hong Kong for their L1A1-F1 rifles compared to a late production Australian F1 or New Zealand BFA for the L1A1 rifle. The restrictor of the F1 (Special) BFA was painted red to show it had a shorter tube than the standard F1 BFA. (Photo: Kevin Adams)
Below: The standard F1 BFA restrictor compared with the shorter F1 (Special) restrictor for Papua New Guinea and Hong Kong L1A1-F1 rifles. (Photo: Kevin Adams)
The F2 (?) [confirmation of the designation was not available at this writing] BFA for the L2A1 automatic rifles supplied to Malaya and Trinidad was very different from the F1-series BFA's. The F2 BFA had a large circular plate, with a latching detent spring attached, and a threaded restrictor plug. The end of the L2A1 automatic rifle barrel had a special recoil reducer attached instead of the five slot flash eliminators on Australian L1A1 and L2A1 rifles. The muzzle end of the recoil reducer was threaded to accomodate the BFA.
Above: The prototype F2 BFA for L2A1 automatic rifles supplied to Malaya and Trinidad with the special recoil reducer. In service the F2 BFA was painted yellow like the F1 BFA for the Australian L1A1 and L2A1 rifles. This BFA screws into the large recoil reducer fitted to the Malay and Trinidad L2A1 rifles. (Photo: Kevin Adams)
Continued in Part 3
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