600 yard steel shooting with 5.56 - 9/2/2017 - Sub MOA @ 1000 (lol but for real)

[Eurodriver]

9/22/16 All of the pics are gone due to a photobucket problem a few weeks ago. But new pics are in post #209

I'd like to personally thank Noodles' bundle of pessimism for giving me the motivation to make this possible.

Post #54 has my build progress so far. Much of this OP is irrelevant now but lots of good info from SMEs and pros in the responses.

I've got a lower begging for an SPR build. I would like to shoot 4" steel hangers at 600 yards with it. I previously had a Noveske upper in 300BLK that was a tack driver and great for hunting but that round will not reach 600 yards.

Questions:

What barrel length should I go for? This will be shot suppressed. I am fairly set on 18" as it will provide a boost in velocity without being too long, but I will consider 16" or 20" if someone can provide quantitative and qualitative reasons for doing so.

On that note, what upper should I buy? I'm really liking the BCM 18" with KMR-A 15" price point. It's like $800 delivered with a rail panel for my Atlas.

What load (I reload) or factory ammo should I be shooting to do what I'm trying to do? I have no experience with precision 5.56mm.

My lower has a carbine RE. I'd prefer not to remove it and get an A5 but I will if necessary. Can a carbine RE work with an 18" barrel? What buffer would I need?

I have an 2-8x Vortex already mounted in a Bobro from a previous build. I've shot to 600 yards fairly well with a 4x ACOG but never at 4" hangers. I plan on upgrading the scope eventually as I know it isn't ideal, but will the 8x be a waste of my time or can I get away with it for now? $1000 for an upper is a lot easier to swallow than $2500 for an optic and upper.

[Onyx Z]

The velocity difference between 16" and 18" is not THAT much... from my experience, it was <100fps with my 77gr handloads. I have 2 18" Rainier Ultramatch barrels (rifle & intermediate gas) and one Noveske Recce 16" barrel (mid-length) and they are all tack drivers. With that, I do like the 18" barrels more, but the 16" is more handy if walking around (i.e. hunting). If only target shooting, I would grab the 18" every time. Longer gas system/heavier = less recoil. Not that 223/5.56 has much recoil to begin with... but it should help you stay on target to see impact.

Run some ballistic calculators with 2,700fps for the 18" and 2,615 or so for the 16" and you should have a fairly good idea on the difference in drop with 77gr pills. The suppressor should boost the velocity a little also.

You don't *need* the A5, but it sure is nice to have. I ran my 18" intermediate with a carbine RE for a while before upgrading all of mine to A5's. I don't remember what weight buffer I had, but it seemed to work well.

[Noodles]

The velocity difference between 16" and 18" is not THAT much... from my experience, it was <100fps with my 77gr handloads. I have 2 18" Rainier Ultramatch barrels (rifle & intermediate gas) and one Noveske Recce 16" barrel (mid-length) and they are all tack drivers. With that, I do like the 18" barrels more, but the 16" is more handy if walking around (i.e. hunting). If only target shooting, I would grab the 18" every time. Longer gas system/heavier = less recoil. Not that 223/5.56 has much recoil to begin with... but it should help you stay on target to see impact.

Run some ballistic calculators with 2,700fps for the 18" and 2,615 or so for the 16" and you should have a fairly good idea on the difference in drop with 77gr pills. The suppressor should boost the velocity a little also.

You don't *need* the A5, but it sure is nice to have. I ran my 18" intermediate with a carbine RE for a while before upgrading all of mine to A5's. I don't remember what weight buffer I had, but it seemed to work well.

Good advice. Although I prefer the 16". You won't notice the effect of an extra 2", ever, but at least with the 16" you could reconfigure the upper to be used as a carbine pretty easily, and you will notice the 2" moving around and esp if you do anything in and out of vehicles.

I went 16" on mine and love it. It's light enough that if I swap the scope for an aimpoint, I'm good to go on the same gun.

[Rekkr870]

I would roll with the 16" over the 18" gun. Like others have stated, you will not see much velocity difference between the two. I find the 16" to be handier as well. A 16" will get you to 600 yards no problem, I regularly shoot a 12" plate at 600 yards with a 13.7" Noveske.

My gun loves the factory Hornady .223 75gr Match loads. They also have a 0.39 ballistic coefficient which helps with wind at that range. In my experience it is a sub-MOA load. I've shot this load out to 750 yards.

I'd also use the Vortex 2-8 until you can afford something better. I'm sure it will be fine to use to evaluate accuracy and testing of various loads for your rifle.



Sent from my LG-H900 using Tapatalk

[sinister]

The rounds will get to 600, no problem.

Hitting a 4-inch plate at 600 (asking the rifle to group better than 1-MOA) is a stretch. Maybe on a windless day, free-floated, with hand-loaded 73-77 (mag-length) or 80s (single-fed) and a good scope off front and rear sandbags.

Minute of Hajji (or E-type silhouette), sure. Better than 10/X-ring, don't bet a pay check.

[Noodles]

The rounds will get to 600, no problem.

Hitting a 4-inch plate at 600 (asking the rifle to group better than 1-MOA) is a stretch. Maybe on a windless day, free-floated, with hand-loaded 73-77 (mag-length) or 80s (single-fed) and a good scope off front and rear sandbags.

Minute of Hajji (or E-type silhouette), sure. Better than 10/X-ring, don't bet a pay check.

True, With 77gr SMK/TMK, my gun does it all day.... ME on the other hand....

Any decent mirage on a 4" steel plate at 600 will be the difference between a frustrating miss and a lucky hit. As it is with echos, I know the holds for my 11.5" out to 500y with an aimpoint, so yea, big difference there.

[MarshallDodge]

I wouldn't want to rain on anyone's parade or be the cause of discouragement but I agree with sinister, 4" at 600 is a tough target.

Every 1 MPH of 90 degree wind will move your bullet about 4" at 600.

The difference in velocity between a 16 and and 18 inch barrel is going to be about 75 FPS. This may not seem like a lot but at 600, 75 FPS gives you around 9" less drop and 1" less windage per 5 MPH wind. Personally I like all the velocity I can get as I like to push my 18" SPR to 1000.

For bullets I like the Hornady 68 BTHP and the Nosler Custom Competition 77. That isn't saying that the others aren't as good, just that I can get those at a good price and they shoot great in my guns.

[HKGuns]

I'm a pretty decent shooter and I'm pretty happy with 2- 4" groups at 200, with a rifle that will shoot sub MOA, consistently, at 100 yards.

My longest kill shots on deer with my Sako .308 bolt were at around 240 yards. I wasn't super confident, given the variables, in a clean, humane kill at that distance. I got a bit lucky as they both dropped dead in their tracks with a couple of through lung shots.

Re-evaluate your expectations or you are setting yourself up for disappointment.

[Eurodriver]

I make sub MOA shots 600 yards consistently firing off a bipod with a rear bag out of my Krieger Barreled Rem700 in .308. There should be a pic/thread still up in the precision bolt gun forum of me doing so at 500.

I guess I need to back up a bit with my questioning: Is a 5.56mm AR platform capable of achieving sub MOA groups at 600 yards? If so, what uppers? Is a BCM SS 18" upper going to get me there? Do I need a 20" BCM SS? Noveske? Or should I be looking at 24" Kriegers? Assume the shooter variable is taken out of the equation.

I'm not trying to shoot competitively against .243s and 6.5s. Additionally, there are 6" and 10" steel hangers right next to the 4" so the worst case scenario is that I have to switch to bigger targets should the rifle not perform or the wind get bad, but that 4" bastard is my goal.

[sinister]

Quality of the build in toto is gonna be a determining factor. A 16-inch can reach 600. A "Loose" barrel and Green Tip Ball ain't going to cut sub-MOA.

Give it a whirl with what you got first before throwing money at a goal. I'd go for a fine trigger first (Geissele NM or tuned Milazzo-Krieger II); a quality float tube (whatever configuration you want your SPR-ish); best hand loads you can make; and a really good scope and mount.

A Krieger 700 in 308/7.62 is gonna have some advantage over a short, non-floated/non-enhanced gas gun.

If you're going to build an 18-inch suppressed SPR don't scrimp. Get John Holliger, Frank White, or some other guy who custom turns barrel blanks to build it right. I have no experience with BCM's SPR uppers but have heard they use Criterion (button-rifled) barrels. "Better" maybe, but not "Best" quality.