A blank firing attachment is a device that fits over the muzzle of an automatic or semi-automatic firearm when firing blank ammunition. It serves two purposes, firstly it prevents any material such as wadding or unspent propellant being forced out of the muzzle of the weapon, secondly it forces gases back down the gas system of the weapon to allow it to automatically cycle, sealing the end of the muzzle in the same way a projectile normally would. The FN FAL/SLR rifle in British and Commonwealth service used a wide variety of blank firing adaptors:From left to right these are Canadian C1 BFA; Canadian C1A1 BFA (also British L1A1 BFA); British L1A2 BFA; British L1A2 modified BFA; British L6A1 BFA; Australian BFA. Tonight we are taking a closer look at the L6A1 blank firing adaptor:The technical manual describes this device as:
The L6A1 blank firing adaptor serves as a choke when fitted to the rifle and comprises inner tube, fluted sleeve, main spring and housing. The housing is painted bright yellow. An aperture in the housing engages over the bayonet lug to locate the assembly on the flash eliminator, and when the fluted sleeve is tightened, secures it in position. It is particularly important that the tube is kept clear of carbon deposits. The attachment is to be used only in conjunction with blank ammunition and before firing a check must be made to ensure it is securely fitted to the rifle.Fitting the attachment. Unscrew the fluted sleeve until the threads on the inner tube are completely disengaged from the housing. Insert the inner tube into the flash eliminator and pass the rectangular hole in the housing over the bayonet lug. Screw up the inner tube using the fluted sleeve, until the attachment is tightly locked on the rifle; the serrated teeth will commence to engage before locking is completed. Check that the fluted sleeve is fully tightened and then unscrew two clicks; this action will facilitate removal of the attachment after firing.
A large knob is fitted to the end to make it easier to screw down tight:An NSN number is stamped into the body of the blank firing adaptor, but is very hard to make out due to the thick layer of yellow paint:The SLR manual helpfully includes an exploded diagram showing the internal parts of the L6A1 BFA:The L6A1 seems to have been introduced due to safety concerns about the earlier pattern, with reports of it working loose and being fired off the end of the muzzle in some circumstances. Whether this is true or not is unclear, but something did prompt the army to develop a new and more substantial design of BFA and this pattern would remain in service until the SLR was withdrawn and replaced with the SA80, which itself had a dedicated BFA available.