Ok,  so I have seen all of the threads on 556 being able to take down hogs extremely effectively.  My question is, given a rifle/shooter combo that could hit the target at any given range, at what point is the 5.56 going to run out of steam.

I know a lot of factors go into this, including the entire ballistics calculation, and how much energy is left in the bullet at any given range.  Not to mention the design of the bullet at that energy.

From a practical, and firsthand account, what combination of barrel length (velocity) and round do you use, and what is the maximum range that you can knock down a pig?

87 yards

If I put an extra Teaspoon of powder behind it, can I get it up to a solid 90?  

600-800 yards with a 16-18'' barrel.

Hi,

You are lucky, the US Government already looked into this topic shooting pigs at ranges out to 1000 yards, and controlling hit placement with armored plates with openings in selected areas.  The theory was that the pigs used were the size of the average man (5‘8" 150 pounds - this was 1929) so the results would be the same from pig to human.  

These tests were done in 22-30 caliber in 1929 called "The Pig Board" .  The findings were 22 caliber rifles were ineffective at 600 yards and the effective range for killing pigs with a 5.56mm rifle was no more than 300 yards.  The most effective rounds in the test used 125 grain bullets at 2450 to 2650 feet per second, 25 to 30 caliber.  These rounds were capable of reliably killing pigs at 600 yards.  The 0.264 bullet was especially noted for its dropping power at ranges 300 yards and less.

The rounds used today that would be most similar to those used in the test would be 6.5 mm Grendel, 6.8mm SPC II, 7.62x39, and 308 Winchester.  The rifle developed from the tests eventually became the M-1 Garand.  I guess based on good shot placement per the US Government the 5.56 is good to go for hogs out to 300 yards for the 150 pound variety.

Regards

personally past 200 yards I would start wanting a heavier caliber, I rarely get over 100 yard shots on hogs as it is here.

Not too far actually. About 285yds with a 223 and 385 with the 308 for sure. I've made hits out to 550 with the 308 but didn't bother to recover and verify. Now that I have a few decent ARs built for medium range work I may start pushing the envelope again.

this!!!!

I like a .308 for something like hogs at longer ranges, though on the hunts I have been on shots are usually at closer ranges.

I kill hogs up to 400 pounds out to 225 yards with a 5.56mm all the time, same for the .308, usually with one shot.

However far you can consistently hit one in the head. For me that is right around 300 yds. with my 24" bushmaster with 6 X 18 leupold, some people a little farther. My 16" carbine with 1 X 4 leupold right under 200 yds. Body shots I like to stay under 200 yds.

My daughter took this one just under 200 yds. With the bushmaster .223.