Who's shooting roundball ammo and what type. I have a .45 Hatsan Hercules Bully and I couldn't get it to shoot good at all with any slugs ( even though the .45 bully has no choke on the barrel for slug shooting) I watched a few videos of Him Chapman hunting mid and large size game with Hornady Roundballs. I tried the Hornadys in my bully which seemed completely innacurate with slugs and low an behold the gun shoots pretty accurate inch groups at 25 and sometimes less with many going hole in hole. Still wishing I could find a good slug that shoots good in my Hatsan bully but H&N Roundballs for muzzleloaders are cheap to shoot. Now H&N is making Pioneer Roundballs with graphite coating made specific for the airgun market. I just ordered some and plan to see how they shoot in my bully as well. I will do a comparison between the Hornady brand for muzzleloaders and the H&N pioneer for airgunners!! Any info from others shooting Roundballs on accuracy and range You guys or gals are shooting Roundballs at?
I have pretty good luck on my .50 CVA Optima V2 muzzle loaders (have both the discontinued pistol and more recently a LR rifle) using thicker patches and roundball. The pistol is really good at 25 yards, still pretty decent at 50. Working the rifle up to 100 yards now. Use a Lee mold to cast the round balls for it.
I had done a little shooting with round balls, that were breech loaded. I recovered some of the balls from a target that had an X shaped pattern from the rifling on them, the balls had been a lose enough fit in the bore to roll a little when fired, causing the X shaped pattern that may have effected the accuracy of the balls.
For the purposes of an air gun they probably aren't going to be all that practical since your not have the amount of force behind them to expand the lead into the rifling grooves that you get with an actual firearm. I had tried gamo roundballs once before with my airmax 2 pistol and they usually just rolled around loosely. I did have one roundball that had to be mashed into the breech and the end result was that it never left the barrel and needed to be tapped back out with a plastic rod from the muzzle. Now you might try using one felt cleaning pellets behind a roundball (or maybe even something like some cream of wheat packed behind it) to mimic a patched roundball and see if that might have helped it, though again not being a powder burner it probably wont do as much.
No brother that's what I'm saying is at this point my .45 bully which is actually a.454 diameter barrel shoots the Hornady .454 Roundballs for muzzleloader absolutely amazing accurate and with great power no patch used. ( goes clean through 3 1 Inch boards then through the wall of the garage and still dented my fxdf Harley's fuel tank though thankfully it still holds fuel! The only thing I could get to shoot this reliable and accurate in my Hercules Bully has been Roundballs. I've tried 8 different cast and swaged slugs and no slug shot close to what this roundball ammo does