1, The full form of SPR is Special Purpose Rifle. It’s used on Governmental ,Weapons & Forces in United States

The United States Navy Mark 12 Mod 0/1 Special Purpose Rifle is a semi-automatic designated marksman rifle that was in service with United States Special Operations Forces in the designated marksman role until 2017, also designed to be shorter than standard weapons.

The SPR was eventually type-classified by the U.S. Navy as the Mk 12. The weapon was developed by the Naval Surface Warfare Center Crane Division for US special operations units, not for Navy units in general.

United States Navy Mark 12 Mod 0/1 Special Purpose Rifle (SPR) is a rifle in service with United States Special Operations Forces in Operation Enduring Freedom and previously in Operation Iraqi Freedom. SPR initially stood for Special Purpose Receiver, but that nomenclature has been replaced as the weapon became a stand-alone weapons system, and not just an add-on upper receiver assembly (part of the proposed SOPMOD upgrades). The SPR was eventually type classified by the U.S. Navy as the Mk 12.

The SPR, used by Special Operations Forces of both the U.S. Army and U.S. Navy, is a heavily modified light designated marksman variation of the M16 line of infantry weapons, chambered for NATO standard 5.56×45mm ammunition. The SPR concept was originally proposed by Mark Westrom, currently president of ArmaLite, while working at Rock Island Arsenal in 2000. The program was an outgrowth of the desire by both US Army and Navy special operations forces for a rifle with greater effective range than an M4 carbine but shorter than a SR-25. The SPR program appears to have grown out of both the SOPMOD Block II program, and the U.S. Navy SEALs Recon Rifle, a 16″ flat-topped M16 carbine. The Naval Surface Warfare Center, Crane Division expanded on the Recon Rifle.

2, The full form of SPR is Surface Plasmon Resonance. It’s used on Academic & Science ,Physics in Worldwide

Surface Plasmon Resonance (SPR) is a widely used label-free detection technique for studying binding behavior of biomolecules. Since its commercialization in 1990’s  SPR has made vast advances in terms of both development of the technology and its applications. It has become a central tool in biomedical research, biosensor development and drug discovery. Over the last ten years, SPR has also been coupled with other techniques such as electrochemistry (EC-SPR) , HPLC, and mass spectrometry (SPR-MS) , and has been used for trace detection in the gas phase (SPR-gas detection). One of the most significant developments in recent years is SPR microscopy (SPRM), a technique that combines high-resolution optical microscopy with SPR technology. SPRM provides the benefits of both techniques and offers direct spatial visualization of samples and real-time measurements of binding affinity and kinetics. It has been challenging to study cell membrane protein binding with drug candidates or other ligands for conventional (channel based) SPR because the extraction of proteins from cells and immobilization of purified proteins onto the SPR sensor are not only laborious but also change the native environment of the proteins. SPRM has significantly improved such measurements by affixing cells directly on the SPR sensor, thereby keeping proteins in their native states . Furthermore, distribution and local binding activities of membrane proteins in each cell can be determined and mapped.