How suicide with a rifle

Not using a profile anyone I know would find. I can't believe I'm even asking this, but I don't know much about firearms, and I know that my husband ended his life with a .22 rifle. I have become obsessed with the desire to know it was quick, like instant. I don't know how this is done with a long gun like a rifle. I have this information from the coroner's report and autopsy. We did not know his plan or the plummet of his mental health. I know he had a .22 rifle that he hadn't used since the 80s and his dad kept it. I guess that was the weapon he accessed for his plan and I don't know why but I don't understand how you put a rifle to your own head. Is your arm long enough to pull the trigger? It's been 10 weeks and this is the point where I beg for reassurance that his last moment was not painful, though his previous weeks were. It was a shot to his temple, so like I guess you don't have to use your toe. I just can't find this detailed information and I don't know why I need it. I'm putting together the pieces of that day and it's important.