Cargill was born in Fort Lauderdale, Florida.[6] He spent his early life in Florida.[7] Later, he joined the U.S. Army and served for twelve years, earning Army Achievement Medals, Commendation Medals, and Good Conduct Medals.[6][7] He also qualified as a marksman and as a parachutist. After an honorable discharge as Sergeant, he moved to Texas, where he initially worked in telecommunications and later started a freight company.[6]
Cargill became interested in firearms education following an assault on his grandmother, which led him to focus on teaching self-defense.[7][8] In 2011, he founded Central Texas Gun Works in Austin.[6][9]
In 2014, Cargill ran for the Texas House of Representatives to represent the 50th district in a special election held in January, but he was unsuccessful.[10] In the same year, his store was named America's first Bitcoin gun store.[11]
In 2015, Cargill initiated a lawsuit against the City of Austin for its decision to declare City Hall a gun-free zone following the statewide legalization of open carry in most public places.[12] The legal dispute concluded in 2019, with Judge Lora Livingston of the 261st Civil District Court ruling in Cargill's favor and fining the city $9,000 for denying entry to licensed gun holders on multiple occasions.[13]
In 2017, a member of the Austin City Council nominated Cargill to a board addressing traffic issues in Austin, but he was rejected by other council members due to his views on the Second Amendment.[14]
In June 2022, Cargill served as the chairman of the Log Cabin Republicans (LCR) of Texas, a group of gay Texas GOP members.[15][16][17] He continues to serve as the president of LCR's Austin chapter.[15]
In June 2024, Cargill successfully challenged a federal ban on bump stocks, culminating in a 6-3 U.S. Supreme Court decision.[18] The court determined that the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) could not classify bump stocks as machine guns under existing legislation.[18] This ruling came after Cargill, who had surrendered two bump stocks to the ATF, filed a lawsuit arguing that the agency had exceeded its authority.[18][19] The challenge was supported by the New Civil Liberties Alliance.[18][19] The ATF's inclusion of bump stocks under the "machinegun" category followed the 2017 Las Vegas shooting.[18][19]
Cargill also provides firearm training for disabled individuals across Texas.[20][21][22]