"The Second Amendment has been under attack — especially on college campuses," Spencer said on the programme.
"So I think it's really important to empower people to show that you should be allowed to protect yourself. Your rights don't stop at a college campus."
Despite attracting serious criticism on social media, Spencer stood by her post.
"It's really, really important to empower the tens of millions of ... gun-owning women and let them know that they have a voice," she said.
"It's really, really important to stand up for what you believe in. It's important to voice your opinions."
The post has already attracted almost 90,000 "likes" and more than 12,000 comments.
Students walked out of school to protest gun violence in response to the previous month's shooting of 17 people at Florida's Marjory Stoneman Douglas High School. Photo / AP
And although Spencer was roundly slammed for the post, she also had plenty of support from other gun enthusiasts such as Edward Hazzard, who posted: "Good for you! Don't let the loony left try to control you, or push you around! We're all here to support you."
Others, such as Reed, were pro-gun but disagreed with Spencer's motives: "I'm 100% pro gun but brandishing a firearm for a photo shoot or showing it off to try and look cool is just stupid. They are tools. Why brag about carrying a gun?"
Spencer's post was published in the midst of the fallout from the February 14 Stoneman Douglas High School shooting in Florida, when 19-year-old gunman Nikolas Cruz killed 17 students and staff members and injured 17 others.
It is one of the world's deadliest school massacres, and sparked an instant wave of protests and student marches and renewed calls for tougher gun laws.
Survivors including 18-year-old Emma Gonzalez have emerged as leaders in the gun control debate, which continues to rage in the country.
US radio host Jamie Allman's programme was recently pulled after he threatened to sodomise fellow survivor David Hogg with a "hot poker".
According to the Gun Violence Archive, there have been 62 mass shootings, 3889 gun deaths and 6797 gun injuries in the US in 2018 alone.
Real-time data for the first 100 days of 2018: •3,889 gun deaths •6,797 gun injuries •164 children (age 0-11) shot/killed •684 teenagers (age 12-17) shot/killed •448 incidents of defensive gun use •451 unintentional shootings •565 armed home invasions •62 mass shootings pic.twitter.com/FBZ5aPygUB
