Nipples vary in size as well as caps so it's a good idea to make sure they fit well when at the range instead of waiting to check when hunting after changing either. Nipples can become peened at the top and caps won't fit well, can be fixed with a little judicious trimming with a hand file or replacement. I don't remember the RWS particulars, it's been close to 10yrs since that happened, but it has taught me to look at each cap to make sure it has priming inside before I cap up when hunting. I like my caps to fit snug and not loose, makes em stay on better and also makes it easier to waterproof my ignition when hunting in foul weather. I would recommend you use a good grease that is used for breech plugs to coat the threads with when installing a nipple, does 2 things, makes em easier to remove and prevents water from following the threads and ruining the powder. I have used automotive anti-seize, TC gorilla grease, beeswax/neatsfoot oil and lately Super-Lube for nipples and breech plugs. Once you get sighted in, I would not recommend changing brands as it could change the accuracy, but probably not by much as far as hunting accuracy goes. For one thing, knowing that a particular load combination shoots real good adds a confidence factor to your hunting/shooting skills and makes for a nicer hunt. hth, Tim
