Load development issue

[millertime2]

I tried some load development for my rifle today. I went from 44 grs of varget to 45.4 grs in .2gr increments it seemed like 44 was about my best group but the problem I noticed was that the fifth shot of each group usually was a flyer high. A couple of times I had the best group I have ever shot through 4 rounds and then the fifth went high. Is this my barrell heating up that's causing this? I started letting it cool between strings on the last few, then four pretty good grouped shots then a fifth high? Any ideas?

 

[Pinecone]

OCW Overview - Dan Newberry's OCW Load Development System

When I work up a load, I use this method.

I shoot the groups round robin style. First shot is first load at first target, second shot is second load at second target .. to the end, and they repeat with the second round of each load.

I wait 2 minutes between each shot for barrel cooling.