If you have been single-feeding the rounds and allowing the extractor to snap over the case rim, that extractor may have already taken a "set"... which is why it would appear tight in the bolt raceway—perhaps. I single round feed mine all the time but I always click the shell into the mag and allow the bolt to pick it up.
The 527 has a very stable ejector design that relies on inertia of the rearward moving bolt. You do need to operate the bolt in a positive manner because the ejector just sits and waits for the bolt to drag the spent case back... try it more briskly. I have found the same with the pickup of the cartridge... that you need to operate the bolt firmly. If this is difficult make sure you run some good quality grease in bolt raceway both sides. CZ bolts can be prone to bind a little if they are pushed into battery off axis... when dry. Also make sure you have grease behind the lug under the extractor that area often gets neglected because it's not in sight most of the time.
Try some good grease, and be deliberate about cycling the bolt... maybe get some snap caps to practice this?
Edit... and actually I re-examined the photos and I can see that the extractor has taken a set I think... see image... there should be no gap here.
Last edited by Sweet Shooter; December 18, 2014 at 06:09 PM.