By implementing an FPGA-based simulator, we investigate the performance of high-rate quasi-cyclic (QC) LDPC codes for the magnetic recording channel at very low sector error rates. Results show that error-floor-free performance can be realized by randomly constructed high-rate regular QC-LDPC codes with column weight 4 for sector error rates as low as 10-9. We also conjecture several rules for designing randomly constructed high-rate regular QC-LDPC codes with low error floor. We also present a decoder architecture that is well suited to achieving high decoding throughput for these high-rate QC-LDPC codes with low error floor