Just a WAG but I think a rough tight chamber might be more prone to fail to extract once hot. Id polish the chamber or at least buzz it with a brass brush, oil and a hand drill. If the cartridge is being delayed from extracting it might zap momentum from the BCG thereby not having sufficient recoil energy to chamber the next round.
If the 450 isnt feeding from the magazine without being fired but hot Id inspect the extractor. The extractor might be tight fitting and when hot the case rim is failing to slide on to the bolt face while chambering. There is a mod to the ejector where you break the edge to permit large diameter cases to more easily feed.
https://bulletin.accurateshooter.com/201...artridges/
If the 450 isnt feeding from the magazine without being fired but hot Id inspect the extractor. The extractor might be tight fitting and when hot the case rim is failing to slide on to the bolt face while chambering. There is a mod to the ejector where you break the edge to permit large diameter cases to more easily feed.
https://bulletin.accurateshooter.com/201...artridges/