He is referring to a sample size of 1. If he had an inventory of 200 MR556 rifles with the same problem, perhaps it would elicit further attention. I'm not saying it's impossible, but the significant majority of MR barrels (and pretty much any HK barrel for that matter) will likely not be key holing after 10K IF used within that particular weapon's design parameters. If they were running the MR like a belt fed doing back to back beta mag dumps on a select fire lower, I can see the possibility of burning out a barrel prematurely. Without knowing the details as to how it's been used for the last 10K rounds, I'd say take it with a grain of salt.High round count AR/M4's (over 100,000 rounds) and how they have handled on our range - AR15.COM
The owner doesn't have a dog in the fight, sees a lot of rounds go down range including suppressed and with the fun switch. He doesn't seem too impressed with the MR556 barrels. Anyone else get keyholing after 10k rounds?
Some of the stuff in that thread was interesting, just not sure I buy all of it.