My big brother was just out of the Air Force and gave my a 700 BDL in .30-06 for Christmas. I think I was 12 years old. With that rifle, I killed my first deer (whitetail), my biggest whitetail, my biggest mule deer, and the most deer. (The first kill was a red squirrel on Christmas day.)
I swapped out the original stock (which I wish I still had, because nostalgia is a funny thing) in the mid-1980s for a black plastic thing with a built-in sling. Butler Creek, maybe? In the early 1990s I shot that rifle a lot with handloads, to include cast bullet loads. By "a lot", I mean in the neighborhood of a 100 rounds a week, on a pretty regular basis. Sometime around then the rifle went into a HS Precision stock, which it still wears, with my nifty paint job.
By the mid-2000s, the rifle would still hold one MOA for five shots with loads it liked, but I had to seat bullets so far out that I was worried about running out of mag box. It went to PacNor for a stainless tube with factory contour. Around the same time, Brownells had Timney triggers on sale. One of those went on the gun.
I won't even try to guess the different bases/mounts/scopes the rifle has worn. I know the first scope was a Redfield 2-7x. Probably used a Leupold 2.5-8x. Now it wears a Kahles 3.5-10x in Talley Lightweights.
I think all this counts as still owning my first big game rifle.