Most forged parts start as lumps of steel that are beaten into a rough shape of the part being made, and then machined into that part, and heat treated to whatever degree of hardness that is needed, Investment casting as is being done today produces a part that dosen't need nearly as much machining, and is cheaper to produce,(The key word here is cheaper) I assume they, are also heat treated, Forged parts in my opinion will wear longer than the cast parts,Look at the receivers on the Garands the CMP is selling, these are forged machined parts,(as are alot of parts on a M1)I'm pretty sure, if memory serves me right, they took over 100 machining operations for each receiver, most are 50 years old or older, they are still going strong, not even close to wearing out...look at the receivers that S.A. is putting on their "New Garands" a investment casting, made in Austriala, and they've had(and still are) some problems with them,(out of spec.) How long will they last? I don't know,But on a M1, I'll take forged parts, thank you, Look at it this way, if the gov't thought cast parts would stand up to the abuse the m1/m-14 was going to get from long term everyday use, they would of used them, but they insisted on forged parts, because they will (again in my opinion) last much longer... The receivers that S.A. uses on the M-14 are also cast, here in the U.S, and from what I've read here and elsewhere they don't have too many problems with them, my guess would be tighter Q.C. than their friends in Austrialia have...The part that scares me is they are using cast bolts, That's a part that has to be right, and There's one place I would insist on a forged part, I don't know if they do, but the cast bolts should be magnafluxed before sent off for assembly...