My little list for the small arms of the Union Army during both Great Wars.
Pistols
Colt M1911 - .45 ACP. The first service automatic pistol adopted by the US Military, used throughout the two Great Wars.
Smith & Wesson M1915 - .45 ACP (OTL M1917 Revolver). An interim pistol adopted during the 1st Great War, features the half moon clips.
Colt M1901 - .45 Colt and later .45 ACP (OTL Colt New Service Revolver.) Introduced at the turn of the 20th Century, the M1901 revolver was the mainstay pistol of the US Military until the early 1930s, when they were withdrawn to 2nd Line Use.
Hi Standard HDM - .22LR. A suppressed pistol specifically developed for the Union Military's Intelligence, the Office of Special Services as a weapon for their secret operations behind enemy lines.
Rifles
Garand M1936 - 7.62x63mm. Originally a Quebecois designed and made rifle, 80,000 would be ordered by the Union Government for a desperate need of modern rifles.
Johnson M1941 - 7.62x63mm. Developed a cheaper alternative to the M1940 with a total of 533,000 being manufactured between 1942 and 1944.
Springfield M1940 - 7.62x63mm (similar to the FN Model 1949.) A planned replacement for the 1903 rifle, only 91,000 rifles would be produced by the time of Operation Blackbeard, after which production would be focused on the 1903 rifle.
Browning M1917/M1917A1/M1917A2 - 7.62x63mm (OTL BAR rifle.) Developed as an Assault Rifle, but becoming a squad support weapon.
Springfield M1903 - 7.62x63mm. A Union made adaptation of the M98 Mauser action, the M1903 would be the standard rifle for both World Wars for the Union Army with a total of 7,072,000 rifle built.
Springfield M1895 - 7.62x63mm. In the 1890s, the Springfield armory would develop a Mauser rifle with elements from the Krag rifle. A total of 1,903,000 rifle built from 1896 to 1903 and saw use during the Great Wars.
Winchester M1941 and M1944 - .30 Carbine (OTL M1 and M2 Carbine.) On the very eve of Operation Blackbeard, the Union Army would develop and introduce a rifle that was to equip units such artillerymen and truck drivers. The M1944 was a select fire variant. A total of 5,820,000 rifles produced.
Springfield M1873 "Trapdoor" - 45-70 Government. During the 1st Great War, the old Trapdoor rifle was used by Rear Area Troops.
SMGs
Thompson M1921/M1928/M1928A1/M1941 - .45 ACP. The first Submachine-Gun for the Union Army and the mainstay for the 1st half of the 2nd Great War. A grand total of 1,262,000 guns manufactured from 1921 to 1944.
United Defense M1942 - .45 ACP. An emergency weapon developed after Blackbeard, the M42 was used by the Union Army as well as by the Black Resistance Movements and others within the Confederacy, a total of 800,000 guns manufactured.
Colt M1942 - .45 ACP or 9x22mm. Another emergency weapon, but this weapon was rejected by the Union Army, but was dropped to Anti-Confederate Resistance Movements by their thousands.
Reising M1942/M1942A1 - .45ACP. An emergency weapon developed for the Union Military during the Second Great War with a total of 654,000 guns produced.
MGs
Johnson M1941 - 7.62x63mm. An LMG adaptation of the M1941 rifle, 186,000 guns built between 1942 and 1944 as a emergency weapon. Proved to be a popular weapon with the Union Paratroops, who preferred this over the BAR M1917.
Browning M1919 - 7.62x63mm. A Development of the Browning M1913 gun, which was modified into an air cooled weapon.
Lewis M1913 - 7.62x63mm - Standard LMG and Aircraft Machine for the US Armed Forces during both wars.
Browning M1895/M1895/14 "Potato Digger" - 7.62x63mm. Used heavily during the First Great War, used for training and reserve during the SGW.
HMGs
Browning M1913 - 7.62x63mm (OTL M1917 Machine-Gun.) Standard heavy machine-gun during both Great Wars.
Browning M1921 - 12.7x99mm (OTL M2 Browning.) Standard Heavy Machine-gun for the Union during the GW2 and beyond.
Colt M1943 - 20x82mm. A licensed copy of the German MG-151/20 autocannon, which is usually mounted on Union Aircraft.
Shotguns
Winchester M1897
Winchester M1912
Ithaca M1937
Remington M1931
Other
M1942 "Stovepipe" (otl M1 Bazooka)
M1939 Anti-Barrel Rifle (OTL Winchester .50 cal Anti-Tank rifle)
M1944 Recoilless Rifle (OTL M18 Recoilless Rifle)
Solothurn S-18/100