.308/7.62 hunting round for use with ACOG

[MTMilitiaman]

I recently got a good deal on an AR-10 with a Trijicon TA-11J ACOG on it. I got the setup for probably about what the optic is worth. It is built on an Aero Precision receiver, Duracoated FDE, with a 16 inch 4150 CMV barrel of about A2 profile and a mid-length gas system on a low profile gas block, sporting a 15 inch Midwest Industries rail. I am already looking forward to hunting with it this coming fall.


The optic is a TA-11J ACOG ( https://www.trijicon.com/na_en/products/product3.php?pid=TA11J-308 ), which is 3.5x with a dual-illuminated crosshair and BDC out to I think 1100 or 1200 optimistic yards. I think it is intended for point targets out to 600 yards with M80 ball in the M14 and primarily area targets with the same round in the M240 beyond that. I intend to get a good zero confirmed that some Federal LC XM80 149 gr FMJBT @ 300 yards. I would like suggestions for an expanding round suitable for deer and black bear from 30 to about 300 yards and that is likely to duplicate the exterior ballistics of the M80 ball rounds I intend to stockpile for practice and Thunderdome use.

And you gotta be careful with those ARs. I've never seen one get up and go on a shooting spree but they do seem to know how to procreate...

 

[Random 8]

Don't take this the wrong way, but with that 16" barrel you are basically shooting a 300 Savage. To come close to replication of M80 ball, look to PRVI 150btsp, or Hornady 150Sst. Both are reasonably priced, and should be in the ballpark. If you and the rifle prove up to the task, I'd personally consider 300 your absolute maximum ethical range. With new dope, a 165 BTSP or BT might stretch that a fuzz. I am not a believer in match bullets for hunting, I think they'll let you down when things go wrong, and poof unnecessary meat when they go right. Some will disagree. For shorter shooting, I favor a plain (pick your brand) 150 flat based soft point at. 300 Sav speeds for deer. I'm partial to Speer.

 

[cheygriz]

150 Speer.

 

[z7]

I would try some 150g Hornady sst superformance. Then go shoot the gun. The acog is good for combat, minute of man, but it’s not perfect. Your rifle is and ammo won’t match the sight perfectly if I had to guess. I recommend a range finder, a sandbag and 40 rounds of ammo. Go shoot it at 100, 150, 200, 250 and 300 and write down the dope/drop

Then get a free ballistic app and figure out where each mark on the scope matches your gun, it might be that with a Hornady sst the 300yd line in the scope is dead on at 325, or 275 because of a short barrel.

This will be ammo specific, so try to find something you are happy with, get good data and only use it, it will take practice to be a real precise system

 

[z7]

Double post sorry

 

[Chuck R.]

With my BDC scopes (basically what you have) I normally:

Find a load the rifle likes (accuracy, MV) for that application and either chrono it or shoot a series of targets entering the should hit VS. did hit data. The software will then compute the MV for you. I then add the cartridge data (MV, BC) along with the scope data/reticle to my ballistic app, in this case Strelok Pro. I can then see what each holdover line really equates to for that load.

As z7 said the normal result will be close, like the 300 holdover is really 318 for that load, but of course the greater the distance the greater the delta. Create a dope chart and tape it to the gun or magazine.

 

[jmr40]

Out to 300 yards the trajectory of any of the common bullet weights from 150-180 will be close enough to hit big game animals. I'd pick a good bullet that was accurate in my rifle and had a reputation as a good hunting bullet, rather than trying to match trajectory exactly. At 300 yards your hunting bullet MIGHT impact 2" higher, or 2" lower than the ball ammo you have it zeroed with. Not enough to cause a miss, especially if you're aware of the slight difference.

Don't take this the wrong way, but with that 16" barrel you are basically shooting a 300 Savage.

Maybe, maybe not. A 308 loses a lot less speed from shorter barrels than most guys understand. And even if true, 300 Savage will still shoot 180 gr bullets at 2500 fps. Short barrels are a compromise, but he's not trying to shoot 1000 yards where every fps matters. At 300 or less the 16" barrel is no handicap.

When working with reduced speeds to start with, then heavier high BC bullets will help. The Hornady ELD-X has proven to be a good game killer, it expands well at lower impact speeds, is very accurate, and is very aerodynamic. They are all heavy for caliber, 178 gr is the lightest .308 bullet they make.

If you could only get 2500 fps you'd still be impacting with 1800 fps out to 500 yards. Which the minimum impact velocity to ensure good expansion. At 300 yards you'd impact at 2050 fps with well over 1600 ft lbs energy and less than 17" drop with a 100 yard zero. That'll kill any game animal in N America

 

[Gordon]

Unless you have an adjustable gas block I would stick to this instead of Superperformance but I totally second the 150 grain SST interlock load as optimum for your gun/sight combo. I am jealous of your gun there, even the stock is a $200 model and what I use on my AR 10s. I have that TA11 on another format and it is GTG at as far as you want to hunt, unfortunely mine is getting to need new tritium
https://www.midwayusa.com/product/3...nition-308-winchester-150-grain-sst-box-of-20

 

[illinoisburt]

Try playing around with a ballistics calculator might be helpful. There are plenty of resources for the BC of most common bullets. There isn't going to be truly huge differences in impact within the 300 yard boundary, especially not that would be evident with a 3.5x optic. If anything, it might save considerable ranging and adjustment headaches by going with the old +2.5" @ 100 zero, rather than trying to fine tune for that 1 or 2 inches of vertical impact using the hashes for real world hunting situations.

http://www.shooterscalculator.com/b...n+168Gr+Hornady+A-Max&submitst=+Create+Chart+

 

[FL-NC]

Keep it cheap and simple, if you can. First try 150 grain Winchester power points, then work your way up (in price) on 150 grain soft points. When you find one that shoots a 2" group or better at 100 yards, stop. Confirm your holds out to 300 on 6" targets. Also, I recommend replacing the stock ACOG base with one from Larue. It will align the ACOG better on your rail. Be sure to follow the instructions. Does it have a good trigger? If not, replace it with one of the $90 units from Larue.

 

[MTMilitiaman]

My dad only got about 2350 fps from the 178 gr Hornady Eld-Xs out of his 16 inch DPMS. He went with the 168 gr Bergers to get a little better muzzle velocity. I really want to stick to something in the 150 gr range with the same general weight and profile as the M80 ball round. I think I might pick up some Federal MSR Fusion and some Hornady SSTs. I have a friend that used a basic Hornady Custom 150 gr SST in his PWS last hunting season. We haven't checked to see how well it matches the BDCs in his VCOG or my ACOG. And at the range he shot his buck, he could have used a bayonet.

The rifle came with the Radian charging handle, BAD ambi switch, and Timney trigger. The trigger is almost too light, esp for a service gun. It can't be much over 3 lbs.

I am expecting somewhere around 2600 fps from a 150 gr out of the 16 inch barrel. At those velocities, I am not worried about bullet performance. I would like an expanding round I know is verified with the BDC out to as far as possible, even if I can't see taking a shot on game much past 250 yards.