I agree with @vetmx posts above, its not easy, even though the videos make it seem so. As far as me, I started slugs with two Edguns, a .22 R3 Long and a .25 R5 Super Magnum. After months and months of testing and comparison, I sold the R5. The R3 got to the point where I could hit a 1 inch spinner on a quad target 15 or 16 times out of 20 from 95 yards.
My next step was an easy one, and I admit I got very lucky. I have a .22 Daystate Bleu Wolf HP with HeliBoard, that shoots RD Monster pellets really well. I decided to try the new JSB KO .217 slugs. All I did was turn the power setting up from 8 to 9 to get them to shoot at 985 to 990 FPS and they are as accurate as the pellets. Easy day!
But I wanted something that could really reach out there with heavier slugs to 200, maybe even 250 yards accurately enough for ground squirrel hunting. So in October I bought a used Impact X .30 with PP, knowing that I wanted to convert it to a .25 caliber gun. So I added things like Ernest Rowe transfer port, FX pin probe, lighter valve spring, Slug A liner, CF liner and CF sleeve over barrel, etc. And I tried slug after slug after slug, all at various speeds. Nothing seemed to shoot as accurately as my Bleu Wolf with the JSB KOs. I had tried all the .25 NSA slugs from 26 to 38 grain. Not a happy camper. And then in the back of my range bag I found a small 30 slug sample pack of the 43.5 grain NSAs. I hadn't tried them because at the approx. 80 FPE the gun was generating, those would only fly at approx. 900 FPS. And silly me, I had read and listened to all the hype about shooting slugs from 950 up to 1050 FPS. Well, safe to say the 43.5 NSA at 900 FPS is truly a tack driver, at 50 yards, at 100 yards, and at 175 yards. For me this turned out to be exactly what I was looking for. And 900 FPS is certainly fast enough and flat enough to shoot out to 250 yards - and accurately! I even won Extreme Field Target with this gun two weeks ago...
So bottom line, its not easy. If you want easy out to 100 yards, shoot pellets. But if you want the benefit of relatively high BC and reaching out past 100 yards, slugs are the way to go, but you have to put in the time...
This is the type of accuracy I get from the .25 Impact with 43.5 NSA slugs. Ten shots at 102 yards prone off bipod. I geek out a bit and name all my guns. This one is Death Dealer.