gas ports, designed to lubricate the long, thin cartridge with gases from the chamber, overcoming the Blish effect and allowing easy extraction of the cartridge. High-Standard produced various models and versions of their classic two-shot over/under derringer in both .22 WMR and .22 LR. The Marlin Model 25MG is a smooth bore, eight-shot, magazine-fed, .22 WMR, bolt-action shotgun manufactured by Marlin firearms Company. It was specifically designed to use snake shot, and marketed as a "garden gun" for use in dispatching small garden and farm pests. It has an effective range of about 15 yards when using snake shot. Based on earlier Marlin .22 caliber designs, the garden gun was equipped with a high-visibility front sight but no rear sight. The Argentine EDDA submachine gun uses the .22 WMR round. In 2014 Kel-Tec released the CMR-30, a PDW-style rifle chambered in 22. WMR with a 16" barrel and a 1:14 twist rate. It uses the same double stack 30-round magazine as the PMR-30. In 2018 Standard Manufacturing introduced an 8-round .22 WMR revolver at the Las Vegas Shot Show. The revolver was originally introduced as the Volleyfire. The gun has side-by-side barrels, and fires 2 rounds of .22 WMR (1 bullet per barrel) with every pull of the trigger. In 2019 the gun went into production and was renamed "Thunderstruck". In recent years, a few UK companies such as Guncraft Ltd have been making semi-automatic AR-15-style rifles chambered in 22 WMR, marketed to civilian shooters who, due to the UK's restrictive gun laws, do not have access to self-loading center-fire rifles. Ammunition The .22 WMR is an enlarged, more powerful version of the much earlier .22 WRF. Despite frequent claims to the contrary, it cannot be safely used in any firearm except those specifically chambered for it. Even firearms chambered for the .22 WRF are not suitable; for one thing, the case lengths are different, and the fact that the cartridge fits into the chamber does not guarantee that using the wrong cartridge is either safe or effective. The .22 WMR was for a time the most powerful rimfire round available; it even outperformed the .22 WCF. It has since been eclipsed in velocity and overall kinetic energy by the .17 Winchester Super Magnum. Commonly available in retail stores, the selection and availability of the .22 WMR nevertheless do not match the popular .22 Long Rifle. Furthermore, .22 WMR is