Here is a rare and unusual item of interest to military weapons collectors. It is a Mann Accuracy Device, built by the military to test rifle calibers. This one is for 7.62 Nato.
The device is built on a Smith-Corona 1903-A3 receiver, serial number 4771874. The bolt is numbered to the receiver. It has a 22 inch Walker stainless barrel. The barrel is marked with electro pencil and reads: "D7553795, F-68-7005 #357 Walker". The stock has been shortened to a pistol grip configuration.
This device is in new unused condition. Bore is mint.
It is unknown how many of these accuracy barrels were made, but they rarely come up for sale.
More information on the Mann devices is available here: http://www.odcmp.org/1001/mann_inc.asp