308 Ballistics: 147 vs 168 grs.

Beretta686 · July 16, 2013, 02:32 PM

I just ordered an ACOG that's calibrated for 168 grain 7.62 rounds, yet I'm sitting on 1000 rounds of 147 gain rounds.

My plan is to zero it with the 168 grain rounds and then shoot the 147 for plinking and such.

Is there going to be a substantial and/or noticeable difference in the flight path when shooting 147 grain rounds through a scope zeroed & calibrated for 168 grain rounds?

rduckwor · July 16, 2013, 02:59 PM

147 should have a lower POI than the heavier bullets. You should be able to compensate once you shoot a few.

Metal god · July 19, 2013, 01:10 AM

OK with out knowing the velocity's of each round I don't no for sure . I ran some known 308 cartridges in those weights through my ballistic calculator .

Federal 168gr GMM , Velocity of 2650fps
Zeroed @ 100yds the rest are drops in inchs - 200yds 4.3" / 300yds 15.4" / 400yds 34.6" / 500yds 63.3"

Hornady 150gr SST , Velocity of 2820fps
Zeroed @ 100yds the rest are drops in inchs - 200yds 3.7" / 300yds 13.4" / 400yds 30.4" / 500yds 56.1"

As you can see it is likely the 147gr bullet will have a faster velocity therefore it will shoot flatter and just a bit higher .

Hope this helps

P.S. remember the ACOG is designed to shoot minute of man and not moa so those hash marks will be general guide lines and not likely law .

Beretta686 · July 19, 2013, 06:58 AM

Awesome. Thanks for the info!

Quote:

P.S. remember the ACOG is designed to shoot minute of man and not moa so those hash marks will be general guide lines and not likely law .

Yeah, I've shot ACOGs quite a bit with the military and they're great for man-sized targets, but it's not a precision scope. Rather they're more of a compromise between long-distance ability and close-up use. But this is mostly a play-toy so I can check-the-box of having a 7.62 battle rifle and shoot milk jugs at 300 meters in between pig hunting.

snolden · July 21, 2013, 10:21 PM

If you can give us a barrel length and make of the ammo we can give you some better info. For example South African surplus will shoot much lower and only be usable with that acog for the first 400 yards. But win white box nato runs 2750 fps out of my 16" barrel and does just fine. Additionally, you can zero at 200 yards for the 147. Then you will be able to use the 100 yard mark for your 200 yard zero. From there you will be within about 6" using the hash marks out to 500 yards.

I shoot 110 gr varmint and 178 gr target out of mine. Their 100 yard zero results in a perfect 200 yard POI for my 147/155's out of my 21" FAL.

It did take me a few years to tweak all those loads so they worked out like that.

July 16, 2013, 02:32 PM	#1
Beretta686 Senior Member Join Date: May 11, 2005 Location: Texas Posts: 761	308 Ballistics: 147 vs 168 grs. I just ordered an ACOG that's calibrated for 168 grain 7.62 rounds, yet I'm sitting on 1000 rounds of 147 gain rounds. My plan is to zero it with the 168 grain rounds and then shoot the 147 for plinking and such. Is there going to be a substantial and/or noticeable difference in the flight path when shooting 147 grain rounds through a scope zeroed & calibrated for 168 grain rounds? __________________ "Our contract called for 16 cases of rifles and ammunition for $10,000 dollars, not a machine gun...........That is our present to the General"-Pike Bishop “When fascism comes to America, it will be wrapped in the flag and carrying a cross.”

July 16, 2013, 02:59 PM	#2
rduckwor Senior Member Join Date: June 26, 2008 Location: L.A. - Lower Alabama Posts: 365	147 should have a lower POI than the heavier bullets. You should be able to compensate once you shoot a few. __________________ RMD

July 19, 2013, 01:10 AM	#3
Metal god Senior Member Join Date: April 10, 2012 Location: San Diego CA Posts: 6,875	OK with out knowing the velocity's of each round I don't no for sure . I ran some known 308 cartridges in those weights through my ballistic calculator . Federal 168gr GMM , Velocity of 2650fps Zeroed @ 100yds the rest are drops in inchs - 200yds 4.3" / 300yds 15.4" / 400yds 34.6" / 500yds 63.3" Hornady 150gr SST , Velocity of 2820fps Zeroed @ 100yds the rest are drops in inchs - 200yds 3.7" / 300yds 13.4" / 400yds 30.4" / 500yds 56.1" As you can see it is likely the 147gr bullet will have a faster velocity therefore it will shoot flatter and just a bit higher . Hope this helps P.S. remember the ACOG is designed to shoot minute of man and not moa so those hash marks will be general guide lines and not likely law . Last edited by Metal god; July 19, 2013 at 01:16 AM.

July 21, 2013, 10:21 PM	#5
snolden Senior Member Join Date: January 25, 2006 Location: N. E. AZ Posts: 387	If you can give us a barrel length and make of the ammo we can give you some better info. For example South African surplus will shoot much lower and only be usable with that acog for the first 400 yards. But win white box nato runs 2750 fps out of my 16" barrel and does just fine. Additionally, you can zero at 200 yards for the 147. Then you will be able to use the 100 yard mark for your 200 yard zero. From there you will be within about 6" using the hash marks out to 500 yards. I shoot 110 gr varmint and 178 gr target out of mine. Their 100 yard zero results in a perfect 200 yard POI for my 147/155's out of my 21" FAL. It did take me a few years to tweak all those loads so they worked out like that.