1. you gather alot of junk (easily possible to gather 2k junk per hour if you use 2 windows and have no downtime)
2. craft 100 desert eagles
3. craft thousands of expanded magazines from junk
4. craft expanded mag deagles
5. drop them all
6. science
repeat since point 4
you always get all unupgraded deagles back after using science and you can keep reupgrading them with magazines (1 junk each) for a nice amount of experience
you can also check description of my video about this leveling method for some more info
https://youtu.be/4VkN1Will3Malso many people dont know but it was me who found this out as first at beginning of this season, i made this way level 100 in 5th day of season
you need max science, dismantler support perk to make it effective
for max efficiency you can also gather alot of junk, reroll to swift learner and loner character, craft these deagles and then reroll to low int combat build.. if you didnt implanted your char yet
for junk gathering make lvl 1 chars with 10st 10pe 10ag
you should also remove walls, use mass science when reupgrading deagles and command "~cb 50" to see where is your junk detection range since it goes even through obstackles, not like FoV