Aussiehunter, I have been trying slugs in my Webley & Scot 12 bore. The gun is proofed for 2.5" case & some one opened up the chamber & the choke (I got it cheap).

My point is - please check your gun. I would not use 3" or 2.75" cases if the proof is for lesser case. I got S&B slugs 65mm (2.5") & Winchester 2.75". The Winchester kicks more & I will not use it anymore. The S&B Brenneke slugs are easy to shoot.

Your Magic ammo is probably made in Italy & a low cost ammo available here in NZ.

I would also suggest that you try the ammo out on targets. As Darryl says, they can be difficult to regulate. Aiming the slug loads accurately also needs practice - it is not the same as shooting with SG / Buck shot. As you can see from my target, the two loads shot 2" to 3" to the right at 20 meters. This will be 7" or 8" at 50 meters. I plan to get a gunsmith to install express sights.