No modifications. These problems wouldn't be due to modifications anyways. I've had some of the same problems that other people on the forum have had and then some.
I put 6000 rounds through mine by game 3 (would've kept going if the gun held up). We need long term skirmish reports. I just don't see this gun holding up over the long term compared to others. But by all means, if someone has had 0 problems even with heavy, long term use, I'd be curious to hear.