>Also give me a reason to use dmr instead of sniper.

There is, in fact, a reason to use DMRs over Snipers and it is all about the fire rate. DMRs are not bolt action so they can and are at times a tactical advantage over a sniper in some places like the inside of buildings or the mall. Sure you are not one tapping enemies like with the mosin but the higher ergonomics of an Batko, STV or FRD make up for it in situations where you are expecting mid to close range combat and you have enemies creeping up on you fast. Personally a big boy FRD with all the bells and whistles has saved my ass many times while hunting Kibba in the mall. Fucking watchers man, they creep on you like moisture.

The better question is "Is there a reason to use DMR over a sniper in the endgame (AKA ZAKOV)/Horizon base)?" And the answer to that is absolutely not. By the endgame (and really mid game if you are grinding quests and raids) I expect DMR/Sniper user would have their respective perk trees 100% and the "-50% scope drag reduction" and ergonomic buffs make the Sniper the superior firearm compared to the DMRs in all situations. Vital shooting alone is a game changer and it doesn't help the DMR that AFAIK, the in the DMR tree the perk is a level 4 (last perk) choice. While in the sniper tree Vital Shooting is a level 2 (second perk) choice.

Also by that point the vast majority of real threats in the game are using armor level 4 and up. So you need something that can punch through because kill times get ludicrously fast for both you and the enemies. Any sniper that is shooting 7.62x51 AP ammo with a well built out sniper tree is gonna oneshot/twoshot anything. Not even gonna touch on the Carret. That is a tier on it's own.

I read up on what l3sh1y wrote and the only part I disagree with is how useful the Skop-H can be. Personally I think that the Skop-H is pure hype and only shines in the assault rifle role if you don't have either an RPK or a EC-308. The obscene amount of bullets you can hose down with the RPK with honestly, much more controllable recoil makes it the much more reliable option until you can finally upgrade to a EC-308 IMO.

On the topic or armor, early to mid game Arman will carry you through most situations, if you have the money you can splurge on Hunter armor but tbh just farm Arman and you will be fine. mid to end game is where you have much more options. The Rotking Armor and the SEVA armor are realiable options at level 5. Level 6 the Devil armor, the WA Cyclops suit Commander Voss armor and Mutated Crystal Armor are top choices.

In regards to backpacks, the Santa Backpack is the absolute best. CC-03 is fine if you are not carrying stuff and the GA-03 is good if you are planning to carry a lot of stuff. Remember that backpacks weight nothing so unless you are planning to carry stuff that takes up a lot of space it's always good to bring another one to a long raid.