What is needed to answer the question is "What type of semi-auto?".
For the older style (Remington 740, BAR), it is usually a fairly difficult job to remove the bolt and the rifle is usually cleaned without performing this level of disassembly. As you can't clean from the breach end, most recommend a guard of some type to protect the crown when cleaning from the muzzle. You also have to worry about dripping dirt-laden solvents into the action. The good news is that this older style doesn't use direct gas impingement.
For the more modern style (AR-15, DPMS), the action breaks open and you clean it from the breach. There is more to clean, and I understand this type of rifle likes to be kept clean for reliable operation. Direct gas impingement tends to get a lot of the internal parts dirty.
For bolt-actions, you can use a bore guide in the action which protects the critical start of the rifling and helps keep dirty solvent out of the action. The bolt removes, so it is relatively easy to clean.
A lot of shooters use pull-through cleaning systems in the field, like a Boresnake or Otis, as these are easier to carry than cleaning rods. I continue to use a cleaning rod, but it's a 5 segment affair that is short enough to fit in a range bag or day pack.