7.62 NATO test loads

v0lcom13sn0w · May 22, 2017

hey guys, was gifted some sized and primed LC 7.62 nato brass.

decided it was time to load it up. i planned to load it for my LR308 so i bought some hornady 150gr FMJBT because they were the grain i wanted and were cheap(er).

have 2lbs of H4895 to burn thru. somewhere i remember reading to reduce 7.62 loads by 2gr from 308 win. loads as 7.62 generally is loaded to lower pressure.

max load for 308 is 44gr from hornady book with H4895 seated to 2.780" so, assuming 42gr is max load for 7.62 nato i decided to start with (and dont crucify me) 41.8gr H4895 @ 2.780"

these bullets have the cannelure and they do look funny seated below it so for sh!t sake i seated some right in the cannelure about 2.725" thinking ok MAYBE i'll shoot these.

first 5 shots with my 2.780" averaged 2647FPS with absolutely NO pressure signs.

next, i figured WTF i'll just shoot these shorter ones.... heres where it gets interesting... with a 5 shot average of 2645FPS with ZERO pressure signs, i was like "

"

am i missing something here?

all brass is LC 7.62 NATO
150gr HOR FMJBT
powder H4895 41.8gr
CCI LRP
seat of 2.780 and 2.725"
with virtually no velocity increase... should i have seen one??? i think so, but i dont know so.

i was hoping for 2650FPS so i think i did pretty good...

Steve M · May 23, 2017

I went through something similar in my M1A with those Hornady 150gr FMJBT bullets. I started out seated long to match XM80 OAL then before going out to shoot I ended up seating down to the cannelure and applied a light Lee "factory crimp". But I was using IMR 4895 and 4064 and didn't do any chronographing on them. Since they feed and fire fine seated to the cannelure that is what I go with now.

From what I've read the affects on pressure and velocity in a rifle resulting from a change in OAL is somewhat unpredictable. This is because as your bullets moves into the case which aught to raise pressure (and probably velocity too), you are also backing away from the lands which has the opposite effect.

v0lcom13sn0w · May 24, 2017

i'll tell ya, aside from my 5.56 this is my 1st high powered semi auto and MAN is it awesome to shoot. makes a 5.56 seem like a BB gun.

v0lcom13sn0w · May 24, 2017

noone else??

jordanka16 · May 24, 2017

Seating depth has a pretty small effect overall on what happens when a round is fired, it's one of the last things I mess with when loading for accuracy, usually I shoot .02" off the lands or to mag length and leave it. 150 gr is pretty light too, hitting the rifling is probably affecting it more than anything else, regardless of where it started its journey from.

jordanka16 · May 24, 2017

before you play with seating depth you should sort your cases by weight as well, the difference in volume from seating depths could be made up by different case capacities.

v0lcom13sn0w · May 24, 2017

jordanka16 said:
Seating depth has a pretty small effect overall on what happens when a round is fired, it's one of the last things I mess with when loading for accuracy, usually I shoot .02" off the lands or to mag length and leave it. 150 gr is pretty light too, hitting the rifling is probably affecting it more than anything else, regardless of where it started its journey from.

yep. these 150gr loads are for my lr308 mainly for punchin holes. if i wanted accuracy id definitely be loading differently