Checking "Breakthrough" again The Austrians did destroy some guns and blow up their ammo before they surrendered. However it later states the Russians found the defenses lightly damaged and put the civilian population to work repairing them. They also managed to get some of the fortresses guns to work which did do some damage to the Germans. Unfortunetly for the Russians the forts around the Przemysl were not proof against the Germans and Austrians heavy siege guns. Besides the 8000 POWs and a number of Russian guns the Germans did recapture a number of Austrian guns captured when the fortress surrendered in March.
And, as I have written above, DiNardo is wrong in this respect. His bibliography lacks the best German-language book on Przemysl, namely "Przemyśl : Österreich - Ungarns bedeutendste Festung"
by Franz Forstner. Naturally DiNardo has not consulted any of the books written by Tomasz Idzikowski, a native of Przemysl and an expert on Przemysl fortifications; Idzikowski's books have never been translated into English, as far as I know.
The Russians might have had repaired some earthworks, even dig new trenches, but the key parts of the forts (panzer batteries, guns, caponiers) had been blown up, and repairing them was out of the question. The scale of the destruction is indeed impressive, even after nearly a hundred years (I have seen three of the forts). By no means can it be described as "light damage".
But even a fort with all the defensive installations blown up remains useful as a shelter for infantry. And that's basically how the Russians utilized them. The forts indeed were vulnerable to heaviest guns, especially since their exact location was no secret to the attackers. In the main corridor of Fort XII "Werner" there is a huge (patched-up after the war) hole in the vault and a matching one in the floor - traces of a 420mm hit. A memorable sight indeed.
As far as I have read, Kusmanek's (commandant of the fortress) performance is unifromly praised; I have never seen any reference to negiligence during the surrender of Przemysl; otherwise - the destruction of fortress' combat value has always been considered as well planned and executed. I'd rather discount the information about the undamaged guns captured by the Russians in the fortress as yet another example of German effort to downplay the value of Austro-Hungarian army.
but from memory there was another siege at Osowiec
indeed, there were two sieges of Osowiec. Both failed. There best reference book is a monograph of Osowiec, based on extensive research in Russian (and other) archives:
Boguslaw Perzyk, Twierdza Osowiec 1882-1915, Warsaw 2004.
Perzyk writes on pp. 190-192, that during the second siege the following German batteries were employed:
Kusten-Morser Batterie Nr 8 (1x28 cm)
Kusten-Morser Batterie Nr 6 (1x30,5 cm) (commanded by Hptm. Baur)
Kusten-Morser Batterie Nr 1 (2x42 cm)
his reference book is: H. Schirmer, "Das Geraet der schweren Artillerie (in) A. Muther, Das Geraet der Artillerie vor, in und nach dem Weltkrieg, Teil 5, Berlin 1937.
Apart from the above, also 7th and 8th Austro-Hungarian Heavy Mortar Batteries were used (both had two 30,5 cm mortars).