TAMPA, Fla. (AP) - Republicans are strengthening the pro-gun-rights portion of their party platform, a defiant response to criticisms that followed recent mass shootings in Colorado and Arizona.

The GOP platform now calls for unlimited bullet capacities in guns. The shooters who killed 12 people in Colorado last month and six people in Arizona last year while gravely wounding then-Rep. Gabby Giffords used high-capacity weapons capable of firing many rounds quickly.

The new GOP platform also endorses "stand your ground" rights for gun owners.

That's the legal concept that says gun bearers don't have to retreat if they feel threatened in a public place. It drew national attention after February's fatal shooting of an unarmed Florida teenager by a neighborhood watch volunteer.