Mikoyan-Gurevich MiG-15bis / WSK-Mielec Lim-2, Polish users

The Mikoyan-Gurevich MiG-15bis equipped the Polish Air Force during the 1950s. Since June 1951 the MiG-15 equipped the Polish 1st Fighter Regiment with additional fighter regiments being set up shortly later. On 23rd January 1953 the first MiG-15bis arrived in Poland, which equipped the 5th Fighter Regiment.
Most of the MiG-15bis of the Polish Air Forcem probably up to 20 copies, were used to compare with the previous version, the regular MiG-15, which was already being manufactured locally as the WSK-Mielec Lim-1, and most of them were integrated into the air force serving most of them with the regiments based in the north.
As it happened with the MiG-15, it was decided to manufacture the MiG-15bis locally under the denomination of WSK-Mielec Lim-2. The first copy rolled out of the factory on 17th September 1954, only after 17 days of the last Lim-1 exemplar. It was produced until 23rd November 1956 with 500 or 530 (depending on the source) exemplars being built by WSK located in Mielec, Poland.
The Lim-2 was equipped with a single Klimov VK-1A engine which delivered a power of 6041lb of thrust (26.87kN) and was locally manufactured under the denomination of Lis-2.
Some Lim-1s were modernized in 1956 by the LZR (Lotnicze Zaklady Remontowe) receiving the unofficial denomination of Lim-1.5 and some of them replaced their guns for tow-equipment in order to tow targets for anti-air regiments. Another sub-variant was the Lim-2 Streak which was a regular Lim-2 equipped with a special smoke-extending device which was mainly used in air parades.
By 1955  almost every fighter regiment and squadron was equipped with Polish manufactured Lim-1 or Lim-2 as the Yakovlev Yak-23 was withdrawn from service and sent to flying schools. Most of the Fighter Regiments were based in the north of Poland, along the Baltic coast, patrolling the airspace from possible NATO intruders like Lockheed U-2 incursions (which they couldn't intecept as it was beyond its service ceiling) or shooting down propaganda balloons sent from West Germany. Franciszek Jarecki, a Polish pilot defected from Poland to Denmark on 5th March 1953 receiving that way the reward the CIA gave for every defector who could bring a piece of Soviet technology, allowing that way the western technicians to examine the aircraft for the first time. He flew from Slupsk, in northern Poland to the Danish island of Bornholm in just some few minutes. There the American specialists, called by Danish authorities, thoroughly checked the aircraft. Jarecki was granted the American citizenship, received a reward of 50.000$ of the time and, according to international regulations, the aircraft was taken back to Poland by ship some weeks later.
The Lim-2 remained in service until mid-1955 when the first MiG-17F entered service with the 5th Fighter Regiment and they were gradually withdrawn from active service.

Sources:
1. https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-15
2. https://pl.wikipedia.org/wiki/Lotnictwo_ludowego_Wojska_Polskiego (translated)
3. https://www.polot.net/wsk_mielec_lim_2_mig_15_bis_english_version/historia
4. https://forum.valka.cz/topic/view/53180
5. Salamander Books - The Complete Book of Fighters