This achievement is cumulative and recognizes stats across multiple playthroughs and chapter select alike. A lot of these will come naturally, but "grinding", as the achievement description suggests, is probably necessary for a few. The achievement requires all Golden Guns and all grinds to be at Platinum status. The word "done" will appear across the emblem when the grind has been completed. I'll share some specific tips that helped me get this achievement quickly. This is my first guide, so please let me know what I can do to improve it, and be patient with any errors. I will do my best to make sure everything is listed properly.
There are a couple of spots in which many of these grinds can be completed simultaneously. Mainly Chapter 4, Checkpoint 5 and Chapter 14, Checkpoint 10 (Credit to AnTiBiTe 2006 for suggesting Chapter 14, Checkpoint 10).
**There have been reports that the number required for completing a grind can be significantly greater while playing offline. This issue seems to be resolved immediately after connecting to Xbox Live.
**There have also been reports of Grenade Launcher and LAW kills not registering properly, especially at the police station. This hasn't happened to me, so I can't shed much light on this issue.
**If your counter for "Blow Out" isn't registering properly, Intengro RYANFU suggests dashboarding or resetting your console.
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First, are the Golden Guns. I used the video guide below to collect them all. The video belongs to RecklessCon, and all credit goes to him.
Bloodbath: 200/500/1,000/2,500 Enemies killed - Kill enemies as you progress through the campaign. These should add up easily, especially while attempting other grinds.
Head Master: 100/250/500/1,000 Headshots - Aim for the head. This is much easier during Bullet Time (Right Thumb Stick).
Arms Dealer: 25/50/100/250 Arm/hand shots - Shoot for the arm and hand during Bullet Time.
Leg Payne: 25/50/100/250 Leg/foot shots - Shoot for the leg and foot during Bullet Time.
Below The Belt: 25/50/100/250 Groin shots - Shoot for the groin during Bullet Time.
Dodge Brawl: 100/250/500/1,000 Kills during ShootDodge - Activate ShootDodge (RB) and kill as many enemies as you can while in the air. On Chapter 14, Checkpoint 10, I averaged 3 kills during ShootDodge. There are plenty of enemies and painkillers on this Checkpoint.
Artful Dodger: 5/10/20/50 Minutes spent in ShootDodge - You could clear out a section of a level and literally press RB + any direction until you complete this, but it will come naturally if you are working on the other grinds, as many of them deal with ShootDodge.
Take Your Time: 100/250/500/1,000 Enemies killed during Bullet Time - Press Right Thumb Stick and kill as many enemies as you can. You will be working on the "limb" grinds and can also work towards "The Turtle" if you have taken cover (X) behind something.
Bullet River: 1,000/2,000/10,000/25,000 Rounds fired - This will come easily over time, so don't waste your ammo during the campaign.
Take A Load Off: 25/50/100/250 Kills while in prone - Along the same idea as The Lounger. While moving forward, left, or right, activate ShootDodge. Once you have landed on the ground, shoot and kill as many enemies as you can while lying down. Move and repeat the process if your targets are out of sight, and remember to stop ShootDodge prematurely (click Right Thumb Stick) to avoid getting shot while suspended in the air. Chapter 14, Checkpoint 10 is a good place to get these kills.
Slow Dive: 5/6/7/8 Seconds spent suspended in the air during ShootDodge - I tried climbing and jumping off of boxes and other random objects throughout the first couple of chapters, but the easiest way to get this is to load Chapter 3, Checkpoint 14. You will be taking fire from a sniper up above, but once you kill the two enemies at the top of the stands, make a 180 degree turn and ShootDodge (RB) off the steps. You might want to "sprint" (I use the word loosely) by holding A before you make your jump. Just watch out for the sniper, and you should have no trouble getting this.
Cam Lover: 100/250/500/750 Bullet Cams watched. The Bullet Cam is initiated when the last enemy of a large group is killed or when you have entered Last Man Standing. In this case, the more painkillers, the better. Boot up Chapter 14, Checkpoint 10, and work on "Cam Lover" and "Back From The Dead" simultaneously.
Wreckage: 25/50/100/200 Vehicles destroyed - Just load up Chapter 14, Checkpoint 13, and shoot all vehicles in sight. Be careful, though, not to shoot the armored car near the end of the sequence. You can shoot the jeep to the left of it, but if you shoot the armored car, an autosave will occur and you will not be able to reload your checkpoint.
Double Damage: 150/300/750/1,000 Enemies killed while duel-wielding - Load up Chapter 14, Checkpoint 10. You will be wielding an Auto 9mm and a 608 Bull. Equip them together and kill as many enemies as you can.
Blow Out: 25/50/100/250 Enemies killed from explosions - Fuel tanks, gas pumps, cars, etc. Anything that explodes will do just fine. Chapter 10 is great for this. Load up the bus sequence (Checkpoint 10). Shoot the man immediately after loading, sit through a quick cutscene, then shoot every gas pump/explosive in sight until you've reached your destination. You'll have unlimited ammo once your bus has made its abrupt stop, so just wait for enemies to crowd around a vehicle, and shoot it up. Play these sequences together, or if you favor one checkpoint over the other, load them up individually. The bus ride is 10-10, and the stand-off is 10-12. (Thanks, Woette)
Guesswork: 25/50/100/250 Kills with blind fire - Chapter 10, Checkpoint 12 is a pretty decent place to get this, but you will more than likely spend more time trying to hit enemies from afar than actually racking up kills. The best place for this is on Chapter 4, Checkpoint 5. Without pressing LT or peeking over the cement barrier, shoot the cars in front of you. The explosions will kill most of the enemies, and the few others can be mopped up easily. You don't have to shoot them directly, deaths cause by shooting vehicles are also counted. Just remember to only press RT.
The Turtle: 100/250/500/1,000 Kills while taking cover - This one is pretty straight-forward. Take cover against a wall or other object by pressing X. From there, just peep around the corner (LT), and shoot!
Back From The Dead: 25/50/100/250 Last man standing "victories" - Find a checkpoint with plenty of painkillers, and take enough damage to enter "Last Man Standing". Make sure your enemies are in the open. Chapter 14, Checkpoint 10 is a good place to boost this.
Fire Works: 25/50/100/200 Grenades or molotovs shot out of the air - I tried several things, but the absolute quickest method is to load up Chapter 8, Checkpoint 4. I used Free Aim, but Soft Lock can be used to help lock onto the grenades. You will approach 3 guys, one shooting a grenade launcher. Take the two guys on either side out first, and step back to where Passos is taking cover. From there, aim your reticle to the sky (where the grenades are "arching") and fire away. Be careful not to shoot them too close to the enemy, or he will die from the explosion. He shoots six grenades before reloading, and I think I was shooting one grenade every three seconds.
Scrapper: 25/50/75/150 Melee kills. Load Chapter 4, Checkpoint 5. Once you start, hop the cement barrier and charge toward the closest enemy who is leaning against the car to the left. Get close and press Y. You will initiate a quick animation, and will need to shoot him. From there, move on from enemy to enemy, taking painkillers as needed. This is also a quick way to get "You Play, You Pay, You Bastard".
Pharmacist: 50/100/250/500 Painkillers used - For most players, this will come naturally by playing through the game a couple of times. If it is one of your last grinds, however, load up Chapter 14, Checkpoint 10 on Easy. You will begin with 9 painkillers. Take damage & heal, rinse and repeat.
Fall Guys: 25/50/100/250 - Load up Chapter 10, Checkpoint 7. As soon as you gain control of Max, look up and shoot the catwalk slightly behind where the enemies are standing. The catwalk will fall, rinse and repeat.
Keep It Simple: 50/100/250/1,000 Kills with handguns - This should come easily for most. Refer to the link at the bottom of the page for help locating weapons.
Shotgun Dues: 50/100/250/500 Kills with shotguns - If you're having trouble getting shotgun kills or even finding a shotgun to begin with, load up Chapter 4, Checkpoint 2. While you're battling it out with the Jersey boys, you'll notice a guy upstairs overlooking the pool table. Once you've taken care of him, grab his shotgun, but save the ammo until a minute or so later when you go outside (Chapter 4, Checkpoint 5). Take care of the guys standing around the cars, then turn and finish the three moving through the gate & reload your checkpoint. You'll be standing in front of the same 8 or 9 guys.
Rapid Fire: 50/100/250/1,000 Kills with sub-machine guns - Refer to the link at the bottom of the page for help locating weapons. Know that the Auto 9mm is actually classified as a sub-machine gun.
If It Ain't Broke: 50/100/250/1,000 Kills with rifles - This should come easily for most. Refer to the link at the bottom of the page for help locating weapons.
Eagle Eye: 25/50/75/100 Kills with a sniper rifle - There are a couple of good spots for this grind. One is Chapter 3, Checkpoint 12 (where you cover Passos in the stadium), also the same place where you can attempt the achievement, "The One Eyed Man Is King". The other location (the location I preferred) is Chapter 12, Checkpoint 9. The reason I chose the latter is because there is an autosave during the Passos segment in Chapter 3 that will ruin your Checkpoint reload.
The Lounger: 25/50/100/250 Kills while lying on your back - Chapter 14, Checkpoint 10. ShootDodge while moving backwards to land on your rear. From there, kill as many enemies as possible. Feel free to get up and repeat the process in another location if you aren't able to hit your targets. Another good tip is that while in ShootDodge, press the Right Thumb Stick to end it prematurely. This will help you avoid getting shot helplessly while floating in the air.
Here is the link to a weapon guide to help those having trouble finding specific weapons. The guide belongs to o KeyserSoeze o, and all credit goes to him.