What weight bullet for 1/10 18" barrel AR10?

[BrianS]

Trying to cut some corners and hope I can find some help here.

I have just gotten my rig, . . .

DPMS LR-308L upper 18", 1/10 twist SS barrel
CMMG Mk III Lower,
Geissele DMR two stage trigger
DPMS LPK
Magpul PRS stock
Magpul MOE grip
NightForce 3.5-15X50 NXS NP-R1 reticle
GG&G Accucam QD mount
Burris Fastfire II MRD
GG&G B-Comp MRD mount
Harris S-LM Bipod Leg Notch Sling Swivel 9-13 inch
Blue Force/Vickers two point padded sling
DPMS carbon fibre fore grip

Weight 11.7 lbs. configured as above, but still a soft shooter.

I know you don't need all that information but I can't help showing off a little.

To make a long story short is there a general rule if I should use heaver weight bullets or lighter weight bullets with a shorter barrel for longer distances?

I'm guessing this rig will serve equally for some Long Range target shooting, multigun and as a coyote/pig killer although I've done very little of any so far. Most long range target will be 600-800 yds and the others will vary greatly I suspect. So just for the long range 600-800 yd shot what should I go with first, heavy or light bullets?

I decided on the LR-308L and 18in. hoping the barrel will be stiff enough for accuracy and to keep weight down. I have been reloading for about a year and some months on a Dillon XL-650 in pistol and .223. Looking forward to your replies.

BTW: did do a google search but got back mostly stuff for pistol. Thanks

 

[rscott5028]

Barrel length would have less to do with bullet weight than the twist.

1 in 10" should be good for up to about 220gr bullets.

Hopefully, someone can give you a powder suggestion based on the barrel length.

There's an AR forum here as well.

Sounds like a great hog gun!

-- richard

 

[BrianS]

Yeah that's what I thought also and what I've read. But I swear I read somewhere on LRH that heavier weight bullets, as heavy as your twist allowed, were recommended for shorter barreled rifles when shooting over longer distances. I've been shooting since the early to mid 60's but didn't get as indepth as I have in the last year or two.

Thanks for the reply.

 

[rscott5028]

The heavier/longer bullets tend to have a higher BC.

For LRH, you generally want the highest BC bullets that your twist will stabilize provided that the bullet design allows for proper expansion with the projected impact velocity at some given distance.

-- richard

 

[cfvickers]

With an 18 inch barrel I would be more concerned with powder than bullet weight. I would look on the faster end of the spectrum for the bullet you choose. You may know that or disagree, but it has worked well for me with my 6.5x55 bolt rifle with a 19 inch barrel. Not a lot of experience with a .308 short barrel, but with the 6.5s I have done best with a medium weight bullet even with a fast twist. Mine is 1/7.75 and it like 120 grain anything better than everything else.

 

[roadhunter]

I have a DPMS AP-4 with a 16 inch barrel. The rifle is factory except for the Chip McCormick 3.5lb trigger. I played around with lots of hand loads and stubled upon one that shoots incredible for a short barreled auto. It will put five rounds in .80 moa all day long from the bench. Mine also shoots the factory Gold Medal Match 168 Sierra Match King too.

Good Luck!

308 Win
150 gr Sierra Game King
45 grains IMR 4064
CCI-BR2
COL 2.800"
Chrono at avg 2726fps and 12fps es

 

[Bearwalk]

Brian,

I have almost the exact same setup as yours. I shoot 180g with good effect and stabilization. Would not go below 180 with that fast a twist. 190s and up would probably work as well. You'll need to experiment a little.

 

[BrianS]

Brian,

I have almost the exact same setup as yours. I shoot 180g with good effect and stabilization. Would not go below 180 with that fast a twist. 190s and up would probably work as well. You'll need to experiment a little.

Thanks Bear got a load you care to share?

 

[Bearwalk]

Thanks Bear got a load you care to share?

I use 40.0g of H4895 behind a Rem Cor Lokt 180g or 180g SGK. The SGK is longer and has more drag so your pressures goes up a bit. POI shift as well.

I have used 41.0g of Varget with very similar results.