The Model of 1938 isn't really a single model, but rather a common set of features. This designation isn't even one that the Turks used, rather it is a designation that U.S. importers have made up. There is the assumption that the Turks took whatever rifles they had and did their best to convert them to the Model of 1938 design. Most common among the rifles called Model 1938 are the K.Kale marked rifles and the Gew.98 conversions. Sometimes the importers even marked converted 1893 and 1903 rifles on the barrels with Model of 1938.

K.Kale marked rifles

It appears that the vast majority of receivers marked with K. Kale are new receivers, probably made in Turkey, clearly some have been manufactured elsewhere and are simply rebuilds. Most K.Kale marked receivers that are obviously rebuilds are from 1940. The only certain way to tell the difference is to look at the receiver face to see if there are old marking underneath the new Turkish marks. If you strip down the action, you can also check the barrel size. Receivers made specifically for Turkey are going to have small shank barrels even when they have the large ring of the 98 series (LRSSM). 

You'll also find that the K.Kale marked receivers will not have a matching numbered barrel. It seems that the barrels were taken off  some other small shank Mausers and assembled on the new receivers. Or, is it possible that they were mismatched on purpose? Again, it isn't clear how this all happened and the Turks have been rather secretive about it.

K. Kale stands for Kirikkale Tufek Fabrikast. This was a state run rifle factor east of Ankara. Other abbreviations or markings that you may see are T.C, Turkiye Cumhuriyeti or Republic of Turkey; .ASFA., Askari Fabrika or Military Factory, ANK ARA or Ankara, and ATF, Ankara Tufek Fabrikast.

T.C	Turkiye Cumhuriyeti	Republic of Turkey
ASFA	Askari Fabrika	Military Factory
ANK ARA	Ankara	Ankara (City)
K. Kale	Kirikkale Tufek Fabrikast	Kirikkale Rifle Factory
ATF	Ankara Tufek Fabrikast	Ankara Rifle Factory

The most common receiver markings for M1938 receivers is T.C., ASFA, Ankara,. This basically means, Republic of Turkey, Ankara Military Rifle Factory. Again, any rifle could have these markings although the K.Kale will usually indicate a receiver that was made at Kirikkale. And ATF will indicate a Gew.98 conversion.

Receiver Face	Receiver Bottom - Z Marked?	Bayonet

K.Kale Serial Number Survey Data

This data was published by "Doc AV" on Parallax's Turkish Mauser forum on 19 September 2002, I've edited it a bit.

Hi-Lo Numbers by years for K'Kale marked rifles:

1940 0? to 26590 - Too few data points to estimate production, probably 30,000.

1941 56800 to 59400 - Too few data points to estimate production, Probably 30,000.

1942 64749 to 110970 - At least 50,000 rifles.

1943 124242 to 152000?? - At least 40,000 rifles.

1944 150500 to 192119 - At least 42,000 rifles, maybe 50,000

1945 200271 to 210022 - At least 11,000 rifles.

1946 224423 to 237721 - At least 13,000 rifles.

Probably 240-250,000 produced over all, if one includes the 1944-46 run of K'Kale marked short rifles in the total.

All Kirikkale marked Rifles have the "B" mark on them, on various parts and under the receiver; some stocks also have "ATF" and "B" on them. The production figures mirror the war in Europe: Ramping up production in 1940, increasing as Germany invaded the Balkans and then Russia: At peak during the Russian campaign, Tapering off as the war ended, with rundown post war.

The Turks, although neutral, were courted by both Germany and the Allies. They staunchly maintained their neutrality to the end of the war, giving haven to Germans escaping the Russian Juggernaut in Bulgaria and Romania in 1944, and from the Allies in Greece in 1944-45.
Of course their surrendered Kar. 98K's and other equipment were immediately absorbed by the Turkish Army.

Regards, Doc AV