I did not make this

Upper/Elder rank--
Reward For Breaking:

Tail- Damage (Any), tail fur will appear ruffled
Narga Tail Spike x2 (75%)
Black Narga Pelt (17%)
Narga Brain Stem (8%)

Wings- Damage (Any), hit the WINGS not the paws
NargaCuttingWing x2 (60%)
NargaCuttingWing (25%)
Black Narga Pelt x2 (15%)

Head- Damage (Any)
Nargacuga Fang+ x2 (70%)
Narga Scale+ x2 (30%)

Carve:

Body-[x3]
Narga Scale+ (45%)
Black Narga Pelt (25%)
Nargacuga Fang+ (15%)
NargaCuttingWing (10%)
Nargacuga Tail (5%)

Tail-[x1] must be in Rage Mode before cutting
Nargacuga Tail (82%)
Narga Tail Spike (10%)
Narga Brain Stem (8%)

Capture:
Black Narga Pelt (40%)
Nargacuga Fang+ x2 (20%)
Nargacuga Tail (20%)
Narga Scale+ x2 (16%)
Narga Brain Stem (4%)

Drop: Sonic when it is in Prowler Stance
Wyvern Tears (38%)
Wyvern Sobs (37%)
Narga Scale+ (25%)

G-Level--
Reward For Breaking:

Tail- Damage (Any), tail fur will appear ruffled
HvyNargaTailSpik x2 (70%)
Narga Tail Spike x4 (12%)
Narga Brain Stem (10%)
BlackNargaPelt+ (8%)

Wings- Damage (Any), hit the WINGS not the paws
StrNargaCttngWng x2 (60%)
StrNargaCttngWng (20%)
BlackNargaPelt+ x2 (12%)
NargaCuttingWing x3 (8%)

Head- Damage (Any)
HvyNargacugaFang x2 (65%)
ThickNargaScale x2 (20%)
HvnlyNargaScale (8%)
Nargacuga Fang+ x4 (7%)

Carve:

Body-[x3]
ThickNargaScale (40%)
BlackNargaPelt+ (20%)
Narga Scale+ (13%)
HvyNargacugaFang (12%)
StrNargaCttngWng (8%)
LeatherNargaTail (5%)
HvnlyNargaScale (2%)

Tail-[x1] must be in Rage Mode before cutting
LeatherNargaTail (75%)
Narga Brain Stem (10%)
HvyNargaTailSpik (8%)
Nargacuga Tail (7%)

Capture:
BlackNargaPelt+ (35%)
HvyNargacugaFang x2 (18%)
ThickNargaScale x2 (16%)
LeatherNargaTail (15%)
Black Narga Pelt x2 (10%)
Narga Brain Stem (6%)

Drop: Sonic when it is in Prowler Stance
Wyvern Sobs (50%)
Wyvern Tears (25%)
ThickNargaScale (21%)
HvnlyNargaScale (4%)

I don't know if this actually works everytime but it has for me. I cut the tail off and I
do not break the face, and catpure it. Everytime I have succeded in doing these three I
have gotten the brain stem. Which isnt very often that I do succeed, about 5 times. I am
not saying that this will always work, but it has for me.

you are not unlucky and there is not a special combo but what i would do is maybe get a
different because other helms may give better bonuses. i have everything garuga except for
kut-ku vamps and a bullfango head because i cant be bothered to get garuga vamps bcause
it's a waste of a monster bone+ and i have bull head because it gives +30 health
p.s i have only just started 5 star quests cause i killed the tigrex about 5 hours ago

i have the full armor, and got it after killing 6 Nargas
cut the tail off, you have a chance of carving it, but a small one
you cant carve it from the body, only the tail
you can get it in a reward, but only if you cut the tail off

try to catch it

well, i think elemental weapons has an effect on what items you'll get. after killing
nargacuga for almost 20 times using flame and thunder elements, i was able to get 2pcs of
brain stem.. sigh..

i need some union ore to make an armour..im already hr 6..where can i get the union ore?in
my poke farm, i mine alot of times can't get..always get
carbalite,iron,dragonite,machalite ore..

http://monsterhunter.wikia.com/wiki/Union_Ore