The Remington 580 series of bolt-action 22LR rifles includes the 580 (single shot), 581 (detachable magazine fed) and 582 (tube magazine fed). They were made over a pretty long run of 1967-1999 (this one was made in 1980.) There was even a 580 “smooth bore” for shooting 22 shotshells. The 580 series was a replacement for the Remington 511 and used 6 rear locking lugs kind of like the centerfire Remington 788 that was introduced at the same time.
The action on the Remington 581 locks up very securely. Personally, I think the multi-lug approach is overkill and unnecessary for a 22LR, and maybe Remington was trying to sell the idea to people who really loved their 788’s.
To remove the bolt, you pull the bolt to the rear, depress the safety down, then remove the bolt from the rear.
The magazine has a slot in the back where the magazine guide goes into. I’m not really sold on the value of using these guides as the downside of them is a more complicated magazine with a breakable slot back and more parts that can potentially break. In fact, the clip guide on the 581 I reviewed here broke and had to be replaced. Some modern day Savage and Marlin rimfire rifles still use magazine guides and I can’t say I’m a huge fan of those systems either.