Interesting to read the various views. I am unconvinced that these Mausers were anything but quickly cobbled together odds and ends that were bought cheap/scrounged from various sources post war. I would be very surprised if at the time they were assembled that the Israeli's even had much industrial capacity to produce a quality barrel either. Who knows for sure? Would sure be interested in reading some accurate Israeli "period" information about their production. My version was not all that accurate and was a real mix master of parts. I am certainly impressed with the amount people ask for them when being sold though.
In 1948 they did scrounge, beg, borrow and steal all the weapons they could. Surplus 8mm mausers were plentiful after WW2 and a few years later they standardized the 98k for the new IDF.
By the early 1950's you had better believe they could build a weapon. The UZI went into full production in 56. The prototype was built 1950 and it was issued to SF in 54.
In 1956 Israel adopted the FN-FAL and produced it under licence. The refurbishing process of the 98K's for the reserves which would be the "Israeli Mauser" started in 1956. The barrels are as quality as anything, I have seen many. Most have dates ranging 56 to 58. They were rebuilt, new barrels in 7.62 installed, most were restocked in beech stocks and either blued or later parkerized.
I don't know if you have ever had an Izzy FAL in your hands, but they are very nice.