Marine Corp Pull ups

I will be leaving for Marine Corp boot camp on the 24th of April and what I would like to know is how to improve my flex arm hang. I'm having a real hard time. I'm not overweight I was five pounds under my max at my physical and I've been lifting weights for the past three weeks for my upper body, but I am still struggling. If anyone could give me some advice to improve my hang time I would greatly appreciate it. I don't want to be the kid struggling in boot camp. I'm extremely determined. Thankyou.

do sets of pull ups
 
but instead of doing 2 crappy sets of 6 reps
 
do 5 or 6 sets of 1-2 good reps that way they are all good reps.
 
also do more back work and arms
 
lat pull downs
one arm rows
close low lats
i would also think biceps but i could be wrong

weighted pull ups.
Yes strengthen the bis
 
I always got the max.
I worked up to doing sets of 20.
 
because that is what they will hope you can do at MCRD!
 
I can pop 20 out any time day or night set after set...because I trained to do that.  I put a bar in my bedroom doorway and did 20 no matter what whenever I could.
 
MCRD is an endurance activity!!!!

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