Solid Hardwood, Engineered and Laminate Flooring - joint tightness?

First timer - installing 3/4 x 3 1/4 inch Bruce Waltham Oak flooring. For kicks, I decided to lay a set of boards (mostly short) across the room to check my calculations/measurements and see which wall I wanted my rip board on. I laid 38 boards across which should have added up to 123.5 inches, but the boards measured 124 1/8 inches. The joints were fairly tight (could see a few slight gaps) but I pretty evenly gained an 1/8 inch over every 8 boards.

So my question is/are:
Should I end up with exactly 123.5 inches with this excercise? Or will tapping/banging the boards into place during the nailing (or the force of the nail gun itself) alleviate the 1/64 inch I am gaining each board?
Should I expect the final installed product to be 123.5 wide?

Thanks for your input...

Each board will be slightly different. The measurements for your boards are close estimates of their true sizes, but not exact.

So, if each board is slightly different, how do I know that my rows will be straight by the end? There's got to be some easy trick - I've watched several YouTube videos of pros just slapping in the boards and nailing them. Heck, they don't even touch the boards with their hands, just rubber mallets and nailer (I had trouble getting the small boards to be straight at both ends by hand). They also don't complete each full row, but work in "steps". Do they just use a better, more consistent grade of wood that is ultra straight? Thanks for any insight.

Jeremy

Did you snap a chalk line for your initial row? If you do this, lay your first row, then the rest should be just as straight as the first.

Most boards are not "perfectly" straight, often times they will nail in one end of the board, then have a helper push in the other end, then nail it in place.

Measure in smaller increments. Trying to layout a full width of a room with narrow boards will lead to errors. Tightly pack say 10 boards at a max and take that measurement. Extapolate to get the full measurement for the whole room. The boards will be tighter than the loose lay as the hammer will bring them tight together. If you remove the baseboard molding and other trim, you have a 1/2 to 3/4" worth of play that will be covered up with the molding. Just make sure you are going to end with a partial board, which means starting with a partial board also. One rare happy occasions, you start with a full board and end with a full board....but don't count on that, its never that easy.

On my starter row, I always use a sheet of MDF hardboard (hard as a rock and true on the edges) cut into strips to provide a "true line" for the wood row. I nail it into place and run my first row of wood against it... Pulling it up later and using a slip spline to reverse the direction of the wood.