Since I don't know how well your bro's-in-law chronograph works, I cannot tell you how big of a deal you're making out of it or not.
Accurate velocity readings are important under certain circumstanced (like CDS ordering etc) otherwise, many a great and accurate rifle has been discounted as poor because of the velocity reading when it really matters little.
I hunted for decades and decades before I had a chronograph and killed everything just fine because I shot to see where I hit rather than just "run the program". I wouldn't be without one now however.
What are you doing or trying to accomplish?