What is the best way to level up in halo reach

The Ultimate Halo XRT62 7 Rangefinder

The Halo Rangefinder can reach as far as 600 yards if you are going for an insightful target. This rangefinder can reach 600 yards under proper conditions. Usually, deer is measured up to 200-250 yards. Too many distances make it generally harder to get correct measurements.
The Halo XRT62-7 gathers light well during a bright day you are completely set. It does not work better in low-light situations, however, as the display is not provided with artificial light. Practically, the rangefinder has been designed with the needs of shooters and golfers in mind, and in this Halo XRT62-7 Rangefinder review, you will know how this product has been helping your fellow golfers and hunters.
The scan mode and 6x magnification which allows for constant ranging. While you are involved on the golf course or in the woods hunting, Halo XRT62 has the rangefinder for you. The XRT62 equipped with a CR2 battery also with a useful protective case, class IIIA laser; 5mW or less.
This rangefinder also works nicely for golfing although you might have to try a few times to get a proper measurement. In such a case, the green object might be captured well by this rangefinder for measuring the distance.

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just google it

Haunted helmet
is the pilot helmet but opened revealing a face which is a skull
can be achieved by unlocking all base helmets and reaching inheritor rank

The Halo PC key refers to your serial key you have for installing your copy of Halo C.E. for the PC. It isn't located on the Halo Reach box or in any sort of pamphlet included with Reach since it is for an entirely different game.

while this is no absolute solution if you google halo reach disc unreadable you will find this is a very widespread issue with halo reach and there does not appear to be an absolute culprit or solution resolved yet. personally I would try to to maintenance on your internal disc/storage
dashboard/my xbox/system settings/memory/your storage device (ie hard drive) press Y on the control while your device is highlighted and do as much maintenance as your willing, I would clear out the system cache initially this is a positive maintenance step and could resolve your issue, all game updates will need to be re-downloaded, but you will not lose any other data. if this fails to resolve your issue you could try something aggressive like a format... but since the issue is widespread and being resolved, I would just try clearing the system cache first.

Unless you have a modded Xbox, you cannot download, as of yet, Halo: Reach.

E74 is a hardware issue you need assistance for the repair of the xbox

Have you completed every level on Legendary difficulty? The achievment will not unlock unless you complete every level on Lengendary, including the very first level which is just a cut scene.