*NOTE* You must have the unlimited Grenades cheat activated *NOTE*
It is quite easy to get 100% accuracy. If you only throw grenades and only use rifles for long range shots, you have a low Shots Fired count and a high Kill count. That translates to a higher accuracy rating. I have often gotten an accuracy rating over 100%.
On the 3rd Canadien mission (Wandersomething I believe), when you reach the barn, there is an endless stream of enemies coming from the barn. If you hide behind a bale of hay in the back, you can take your time and shoot them with the rifle you picked up from the sniper just before or use the M1 Garand you get in the beginning. You can use this to boost your Kill and Head Shot ratio while having little risk of being shot because of the enemy's innacuracy. You can also use this to boost your accuracy after taking out the half tracks.
Get a sniping weapon e.g Kar 98k,Springfield rifle now go to a very thin wall and hold "L" you will be able to see through It! May not work on some walls:(
To unlock the following, you must beat the respective tour of duty (US, Canada and Britan).
Unlimited Ammo - Beat the game on the Green Difficulty
Unlimited Grenades - Beat the game on the Veteran Diffculty
Unlimited Health - Beat the game on the Hardened Difficulty
Play and beat the game on Veteran Mode, then it will ask if you want to switch to survival mode. Select yes and it will switch to Survival Mode.