Solothurn S-18/100

{{short description|German anti-tank rifle}}

{{more citations needed|date=September 2014}}

{{Infobox weapon

| name = Solothurn S-18/100 20 mm anti-tank cannon

| image = Bundesarchiv Bild 101I-189-1250-10, Russland-Süd, Soldat mit Panzerbüchse.jpg

| image_size = 300

| caption = German soldier with the Solothurn S-18/100

| origin = Nazi Germany
Switzerland

| type = Large caliber rifle, anti-materiel rifle

| is_ranged = Yes

| service =

| used_by = See Users

| wars = Slovak-Hungarian War
World War II

| designer =

| design_date =

| manufacturer =

| unit_cost =

| production_date = 1934-1943

| number =

| variants = Solothurn S-18/1000, Solothurn S-18/1100, Solothurn-Arsenal

| weight = {{convert|45|kg|lb|abbr=on}} without magazine

| length = {{convert|1760|mm|in|abbr=on}}

| part_length = {{convert|925|mm|in|abbr=on}}

| width =

| height =

| diameter =

| cartridge = 20×105mmB

| caliber = 20 mm

| action = API blowback

| rate = Semi-automatic

| velocity = 735 m/s with a Hungarian Armour-piercing ammunition#APHE / SAPHE round

| range = 400 m (for penetration of 50mm armor)

| feed = 10-round detachable box magazine

| sights = A dedicated scope

}}

The Solothurn S-18/100 20 mm anti-tank cannon was a German and Swiss anti-tank rifle used during the Second World War. It had a semi-automatic action in a bullpup configuration. As a result of its large, powerful ammunition, the gun had a tremendous recoil, and its size made portability difficult. The feed was either from a five or (more usually) ten-round magazine that was attached horizontally to the left side of the gun. The gun used 20×105mm belted-case ammunition which it shared with the S 18-350 aircraft cannon that was developed from the rifle. A Finnish source gives armour penetration of the gun (probably achieved with the Hungarian APHE-T round, since it was the only type used in Finland) as 20mm at a 60-degree angle at 100-metre distance, decreasing to 16mm at 500 metres.

A variant of this design, the Solothurn-Arsenal, was manufactured without license in Estonia before WW2; however only 20 were produced prior to Soviet occupation.{{sfn|Zaloga|2018|p=23}}

In March 1940, with funds collected in Switzerland to help the Finnish war effort in the Winter War, Finland bought twelve S 18-154 anti-tank rifles from Solothurn, though the purchaser was nominally the Swiss army. The weapons arrived into Finland during the spring after the war had ended, but they were later used in the Continuation War. However, the guns were soon found to be obsolete in their intended role. Various models of the S-18 series, including the Solothurn S-18/1000 and the Solothurn S-18/1100 were also used by Switzerland, the Kingdom of Hungary, Nazi Germany, the Kingdom of Italy, and the Netherlands.

The Waffenfabrik Solothurn firearms company was owned by the German firm Rheinmetall, and used the Swiss company to manufacture arms which were prohibited for manufacture by any German firm to get around arms limitations imposed upon them at the end of the First World War.