A dust cover, like on a 1911, is just there to cover the recoil spring area. The slide rails stop around the trigger guard.
Full length rails are usually found only on guns with with external rails, like yours. The Baby Eagle also has them, and the Sig 210 rails extend a long way. The Sig 220 series are the only guns that come to mind with nearly full length internal rails, and the front of the slide is a little strange because of it.
I also left a message at IDPA HK. The HK P7s dust cover comes within 1/4" inch of the muzzle. Full length? Disqualified? HK USPs have checkered and stippled grips: Disqualified in SSP? They also have full dust covers, so that would cause them to be DQ'd in the other two categories. Is a Baby Eagle with a Witness SA trigger installed also DQ'd for ESP since it can't now be shot in SSP? Inquiring minds think the rule book is garbage.
I'm working on a new pistol that has full length slide rails. Is it already DQ'd?