Here is what I run into with new players.
I'm using a gunnery system based on WWII tank manuals. The manual states the first shot is a ranging shot. At a range of 1000 meters the first shot has about a 30% chance to hit. Historically the crew "bracketed" the target using range or elevation corrections until a hit was achieved. If the shot hits the gun is assumed to be "ranged in" and may have an 80% chance to hit the target but can never be better than 80%.
Before the game I have to give a briefing to the players that almost resembles an overview of a tank gunnery instruction class. Guys that have been tank crew members already know what's going on because they've read the manual and performed the same actions as in the game. They've verified that the gunnery system does to a large extent resemble the real thing with the same risk-reward decisions and weapons platform performance.
While I can state that the game has a high degree of historical recreation (I hate using the term "realism") because the source is the real manual and I use the terminology and nomenclature from the manual. However, most players are going to be clueless unless given a briefing or watch the instruction videos before the game.
Some people pick up on it quickly, some take awhile. If you try to compare it to traditional to hit + drm methods it takes longer to grasp the system.
I've simplified it to the point the mechanics are pretty simple and not any more effort or steps than other games.
I do state the goals of the game and what I'm attempting to portray and where important abstractions have been made. I feel that if the game play recreates to a large degree the designers goal it is a success. As to whether people feel it is "real" or not is pretty much subjective to the individual and their level of knowledge for the era, weapons and tactics and their expectations going into the game.
The game needs to be enjoyable, fun and interactive too. A dry run through of a detailed simulation would be boring in a game.
As a designer I try to assume nothing. Most of the changes I've had to make from play testing were assumptions on my part that ended up confusing the players. If I observe players having difficulty understanding a game concept or mechanic I'll strongly consider changing it or including it in a play aid.
Wolfhag