When you take the breech plug out, there is no problem. When you put it back in, make sure not to tighten it down real solid. Just snug it back in.

As for sighting in, shoot it on a clean barrel and make note of where you hit. Then I use a swab solution made up of 50/50 isopropyl alcohol and car windshield washer fluid. Get a patch wet and swab the fowling out of the bore. Then run two or three dry patches and load and shoot again.

Some rifles, there is a big difference in where they hit dirty/clean. Some are so close it really does not matter. All you can do is try the rifle out and see what it does.

Better luck next time shooting at a deer.