I have just came across a L579 biathlon S#43xxx from '64/'65 in great shape except it is missing the rear micrometer target sight. I have contacted Sako parts and Lyman and posted a WTB on this site for the missing micrometer rear sight to no avail. While I would like to return the rifle to the original biathlon configuration, I cannot do so without a rear sight. I am considering removing the front aperture hooded sight that appears to be soldered and pressed on. The left side of the receiver has rear sight mount that is a 1" block of steel both screwed and welded in one spot to the receiver. Removing both as cleanly as possible will still leave some marking on the barrel and receiver. The rifle is about 98% which makes it a shame to do so. But the front sight and rear mount are useless without a rear sight. The rifle is a .243 with a very heavy barrel and would make a good scoped rifle but the big front sight would be in the sight plane of a properly low mounted scope. Would you hold out for the holy grail of a rear micrometer target sight or modify the rifle and start shooting it. thanks, Joe.