H&r plainsman spring for magazine

I have an h&r plainsman model 865 bolt action rifle, 5 round magazine, .22 caliber. First time i try to load it the first 4 rounds load, but when i tried to load the 5th the bottom popped off & the spring sprang to who knows where. (I was outside). Am i better off replacing the spring or the entire magazine? The spring is the only part missing. Your assistance would be appreciated.

 

Gun parts Corp (Numrich) has the mag for $23.25. I didn't see just the spring listed by itself but you might be able to find one by searching.

 

The magazine looks similar to others, Savage, Remington and Winchester. The spring could be adapted from another brand?

 

I wonder whether having the bottom pop off was a freak one-time occurrence or if it indicates that the bottom piece us worn out and it will keep happening.