Now you know why so many people stick with 3 shot groups
Seriously, I would think it could be 1 of 3 things (Obviously more if you want it to be). You are messing up 1 in 5 shots. The ammo is not perfectly consistent for 1 in 5 shots. Or since you are shooting outside, some crazy atmosphere conditions are happily messing up 1 of your 5 shots every time
Not sure, but other wise those look like some decent groups. Keep it up. and good luck!
Oh, and honestly, I understand your frustration, if you figure it out, let us know. I had this issue with a bolt rifle once... Eventually I found it was the ammo... But when you get what seams like 2 separate tight groups like your picture shows from what was supposed to be one tight group it gets confusing.
You could just as easily be messing up a couple shots in a consistent way to group those 2 or 3 shots away from your actual good shots...
Take advice from some of these other guys and try shooting 1 shot groups, very focused shots, making sure each one is a good shot on your end... then dont choke on the 5th one!
and if you FEEL like you pulled one or lost focus as you broke the shot... forget it, discount that shot. and move on... Then practice practice practice.
I hate to say it, but sometimes for us armatures we need confidence in our rifle and load before we can be confident in our shooting. For the real Pro's it's the other way around. I'm sure they can spot a bad rifle/load combination with just a few shots and vice versa.