In the barn shootout, Matthews fires at least 6 rounds from his 5 shot snubnose revolver.
Colton fires through a closed barn door and hits Wells in the shoulder. Colton could not have seen what he was shooting at, and the heavy wood door would have absorbed the bullet making Wells being shot highly improbable.
Matthews exceeds his lawful authority by taking Alvin's rifle and unloading it while it was inside Alvin's home. He later tells Alvin's neighbors while they were on Alvin's property to forget about their guns and to put them away. The US Constitution in the 2nd Amendment gives the right to bear arms to citizens, and the right to self-defense of persons and property is codified in state laws in what is known as a "Castle Doctrine". California for example has had a Castle Doctrine type of law (198.5 PC) based upon legal decisions from as far back as 1895. Matthews actions also discounted the very likely possibility that two of the farmers were veterans that had seen combat in World War 2 (two of the actors playing the farmers would have been in their 20's during the war) and were proficient with firearms.
For all of his condescension towards the farmers, Matthews approach to the barn with only himself and another officer armed only with handguns was a far worse tactical decision than the plan of the farmers, two of whom were armed with rifles. A better decision would have been to wait for reinforcements that were already in the area. Once inside, Matthews failed to look up where the shot originated even though that is where his return fire went, which allowed Colton to jump onto him.