I have a 5,6x57 RWS. It's a Savage action but built up by Anschuetz. This caliber is a metric that compares to the .220 Swift but with a better twist rate so it takes heavier, (74-grain) better built bullets and is therefore suitable for larger game up to fallow deer size, (where legal). It has 2 adaptor cartridges, which was the norm for this caliber as the case has a special extra thick neck to accept adapters in it's chamber. They're made by Walther, one in .22 Hornet and one in .22 WMR (.22 Magnum). They're not reduction cartridges in the sense that they have a parent case with a reduced internal powder case, rather they're adaptor cases that engulf the smaller case. The .22 Hornet especially is very accurate, despite the apparent mis-match of twist rates. It means I can start off a youngster on targets with the next to no recoil rimfire, graduate to the Hornet on hares and then onto deer as they get older and bolder. My son shot his first deer with it, but he now prefers his Krico .243 although not for any particular reason in terms of extra performance. The 5,6x57 is brilliant on feral goats and would be a perfect roe deer cartridge - if we had any down here in New Zealand.
The reduced hulls sound like a good idea, if used carefully. I just might give them a go.
