Looking at one and need to know what the usgi markings are ?
Is SA a usgi part ?
Yes and no. Per M14 Rifle History and Development at www.imageseek.com/m1a:
"Bolt Markings - A USGI bolt (and receiver) will have a dimple from a prick punch after successful proof round testing. Replacement bolts were proof round tested using a fixture. Frankford Arsenal and Lake City loaded the proof rounds to 65,000 psi. An inscribed letter M on a USGI bolt means it was examined by magnetic particle inspection. Not all USGI bolts will have the letter M though. USGI M14 bolts have additional stamps besides the part number and bolt manufacturer. The other markings are heat treatment and steel lot numbers. Such an example can be found on a bolt marked 7790186 HRT A20 CDR. These are in order: 1) part number 2) manufacturer code 3) heat treatment lot number and 4) steel supplier code. If a manufacturer had only one steel supplier then just the heat treating lot was stamped on the bolt. Other manufacturers consolidated their markings to include both heat treatment lot and steel maker.
The U. S. government Springfield Armory bolt markings can be confused with commercial reproduction Springfield Armory, Inc. bolts. The U. S. government Springfield Armory stamped its bolts in one of two ways, one format for 7790185 bolts and another format for 7790186 bolts. If the bolt was made by the U. S. government Springfield Armory and it is marked 7790185 it will have the following: 7790185-SA on the first line and the heat treatment lot number on the second line, e.g., YO2. U. S. government Springfield Armory bolts made to the 7790186 drawing have this identification scheme: 7790186 on the first line followed and then SA and the heat treatment lot number on the second line, e.g., Z1B. USGI M14 bolts made by Winchester have its CAGE Code, 66118, on the second line whether stamped 7790185 or 7790186 on the first line. Textile Machine Works M14 bolts can have the manufacturer code, HRT, either on the first line or the second line of the bolt markings.
There are bolts with counterfeit markings. Ron Smith of Smith Enterprise, Inc. has seen two M14 bolts stamped TRW that were not made by TRW. Genuine unaltered commercial Springfield Armory, Inc. M1A bolts do not have a prick punch dimple. All USGI bolts were phosphate coated. Any M14 bolt that is bare steel or has a finish other than phosphate coating was not produced that way by the USGI contractor so buyer beware! The bolt installed in the M14 type rifle should be able to pass the slide test as discussed in Kuhnhausen’s manual and have proper lug engagement and proper headspace prior to use."
"Bolt - Springfield Armory, Inc. bolts are typically marked 7790186-SA on the first line and A00030, B00048 or F00059 or similar number on the second line. They may have markings such as D and M3 on the rear end and A9 or B1 on the bottom surface. The letter A prefix for the number under 7790186-SA means the bolt was cast then finish machined. The letter B prefix for the number under 7790186-SA means the bolt was machined from bar stock. The letter F prefix for the number under 7790186-SA means the bolt is forged. See 1987 Springfield Armory, Inc. Recall Notice for additional markings. M1A bolts are not made by metal injection molding. Around receiver serial number 165XXX, Springfield Armory, Inc. factory installed bolts have letters and numerals with a taller and thinner font than the style found on USGI M14 bolts.
Operating Rod - On Springfield Armory, Inc. operating rods, look for either: 1) 7267064 on the first line and SA centered below it or 2) 7267064-2 on the first line and SA centered below it. The first example is the earlier of the two markings. Springfield Armory, Inc. operating rods may or may not have a notch under the handle like USGI operating rods. Before 1996, Springfield Armory, Inc. operating rods did not have a notch under the handle. Sometime between 1996 and 1999, the notch under the handle was added to its operating rods. For clarity, U. S. government Springfield Armory operating rods are marked 7267064 SA all on one line and are machined with the notch under the handle."
Thanks for the Info .