I have never served, have a number of friends who have or currently are, though. I have been competing in 3-Gun, Practical Pistol/Rifle, Tactical Pistol/Rifle, precision no-bench distance, and many other forms of competitive marksmanship that isn't the boring "stack the sand bags just right and get out the 50x magnification optics" stuff. I got involved because I have worked for a small FFL (Class 3 firearms dealer) for the past 9 years, and having always been interested in firearms, the chance to get anything on the market at cost was, and still is, too good to pass up (especially since I don't have to pay for tax stamps for C3, SBR's, or suppressors).
I have grown very fond of "killhouse" training, it's incredibly adrenaline filled and I would equate it to being the autocross of the competitive shooting world (I also race, but at a much higher level of competition than I shoot).
I remember after I had gotten my first HK416, one of the first privately owned in the country, and lucky enough to get the 10.4" upper, 14.5" upper, and 18" upper all as part of the sale.
I threw one of my Gemtech G5-T's on it, one of my EOTech EXPS3's with the G33 3x FtS magnifier, and a SureFire M910V w modified Cree 125/350lumen variable output LED head on the rifle (10.4" upper, 9.5" rail) and spent hundreds upon hundreds of hours putting enough rounds through it that I ordered 3 new barrels the first week I had it, knowing that I would wear one down pretty quickly and not wanting to lose the "all original" aspect of a rare rifle. 18,000 rounds in what seems like no time atall.
The other type of sshooting I like, mainly because it's stress relieving, is taking my AI AWSM .338 Lapua Mag to the 1500yd range, and consistently fail to hit the target lol.
Well, the first time I see one of my buddies aft he returned from a deployment w US Army Special Forces, we went to the range and without having ever fired an AI AW before, he put 5 rounds in a 2.25" group at a grand. Oh, well, he was a sniper instructor so I guess I should have expected that, but if you have never looked through a Leopold 5-25x58 scope at a man size target 1.5KM away, it's like trying to hit a specific blade of grass with a BB gun from 40ft with a 25mph crosswind.
Later, he of course managed, with no effort, to beat my perfect score time by 4 seconds @ the killhouse (most people take years to improve a second, and I was already one of the fastest non military regulars). And he did it with my rifle, again, one he'd never used.
Talk about humbling! Be glad these guys are on our side!