Scope corrections for long range - how far? Also AR Iron Sights

[kayak-man]

Hey guys,

As always, this may be kind of longwinded,and I'll be sure to put the goals and questions in list format at the end for those of us running short on patience.

I've decided that 2014 will be the year when I get serious about getting my hits at longer ranges. At the suggestion of one of my shooting buddies, I've started watching the "Sniper 101" videos on Youtube, and I'm seriously considering investing in a new scope that would be more suitable for shooting at 1000+ yards.

Specifically, I'm thinking of putting an SWFA SS 10 power scope on my Savage 111 30-06, which begs the question, what do i do with the 3-9 power Bushnel scope that's on there now? Well, I've got an FAL in the safe... I'm not planning on turning my FAL into an extreme long range rifle, but I would like to be able to shoot it out to 500 yards, and hopefully still be able to use it for the closer ranges that I would see at a 3 gun match if I ever want to use it for that.

Now that ya'll can see kinda where my head is at, I'm wondering, how far can you shoot before you have to start making given corrections? I'm assuming that if I'm shooting my AR with iron sights at 200 yard, that I don't need to adjust for humidity and barometric pressure, but I might have to take wind into account if its really blowing hard, assuming that I'm using a decent sight that is properly zeroed. I'm also assuming that there my be a few differences between calibers.

My goals are (In order of priority)
I - Make my AR-15 an effective firearm for targets out to 250 yards*.
II - Be able to shoot my Savage 30-06 at least out to 1,000 yards.
III- Make my FAL an effective firearm for targets out to 550 yards +/-**

Questions:

1 - At what ranges do I need to start correcting for:
A-Wind. If this is caliber/rifle dependent at all, I'm thinking in terms of an AR15 in 5.56 and a FAL in 7.62. Chances are with the 30-06 I'll just adjust for wind regardless of distance.
B- Air Temp
C- Barometric Pressure
D - Any other factors I'm leaving out?

2 - If a scope is made for a 30-06 bolt gun, will it be able to handle the recoil of the FAL? I know the FAL kicks less, but it also has a much heavier forward recoil due to the mass of the bolt, so...

3 - If I put the Bushnell scope on my FAL, I will eventually (probably) put one of the 1'oclock angled iron sights on it, but until then, how much of a handycap is it going to be for the run and gun type shooting that I see at local 3 gun matches where you are shooting primarily in fairly large pistol bays? The lowest I can go with it is 3 power, which I figure will be slower, but help yield better hits, and for the super close targets I can just "point shoot."

4 - I just ordered a Daniel Defense A1.5 fixed rear sight. It is not elevation adjustable, but can correct for windage. With the 50/200 yard zero, am I expecting too much from this sight if I try to push it to shoot targets at 250 yards?


* My AR is primarily for 3 gun and HD.
** I know that there may be limitations imposed by my rifle that may keep it from being a 550 yard gun, but I think its a good goal for me to shoot for, and my concerns at this point are largely about the optic, until I have a chance to find out what, if any, limitations that particular rifle has.

As always, if I didn't articulate something very well, feel free to ask me for clarification.

Thanks guys,
Chris "The Kayak-Man" Johnson

 

[hentown]

Wish I had the patience to wade through that post!

 

[LeonCarr]

I will give it my best shot:

1A - Always consider the wind regardless of range.
1BCD - Probably not until shooting out past 400 yards.

2 - Yes, but will require a really stable mount/bases/rings to get better accuracy than open sights from an FNFAL. IME with Match Ammunition a well built FNFAL will shoot 1.5/2.0 MOA with open sights from the bench or prone. With 175 Sierra Matchkings or similar bullet in factory ammo or good handloads, the FNFAL should keep them inside an IPSC Target out to 550 yards with practice.

3 - For 3-Gun type shooting, I would stick to irons on the FNFAL and shoot in the Heavy Metal Division.

4 - The Daniel Defense A1.5 is my favorite BUIS, and 250 yards or further with consistent holdover is 100% possible. With the 50/200 zero you will typically be less than 2.5 inches above or below the line of sight out to 250 yards and about 6.5-7.0 inches low at 300 yards depending on the ammo. A shoulder or armpit hold at that range will put it in an IPSC Target or 8 inch plate at 300 yards.

 

[earplug]

Ballistic chart

Find a ballistic chart that shows the trajectory for the cartrige your shooting. Bullet velocity,bullet ballistic coefficient and range/distance.
An example would be, sight in your scope for a 200 yard zero. Then using the chart you know how far to hold over at longer ranges or adjust your scope for the various ranges.
Wind effects bullets based on ballistic coefficient, velocity and distance. There are charts for this adjustment.
Again hold off into the wind or make a scope adjustment.
Before spending money on 3gun find out what the others are playing with.

 

[Domino]

AR-15
With the AR, the wind is not likely to have enough effect at 250 yards to actually miss a human sized target unless its really going. With a 10mph crosswind, it puts the M855 off roughly 3 inches at 300 yards. For targets from 0-250 yards, your best bet is to get a good red dot and either do a 25 yard zero or 50 yard zero. A 25 yard zero will have the same POI at 300 yards and a 50 yard zero will have the same POI at 225 giving you pretty much dead hold withing those ranges. Pick your poison, I prefer the 50/225 for red dots and 25/300 for irons.

FAL
Here is where you will want some sort of magnified optic. Get the sturdiest base you can find and get a good quality 3-9X/2.5-10X/4-16X scope with good QD mounts. Make sure the scope either has a ballistic reticle that matches your .308 load or is setup with mildot and mil/mil adjustments and learn your holdovers. Getting hits out to 500 yards is pretty easy with the 308 as long as you understand the trajectory, I do it all the time with only consideration of the wind. For fast reliable hits, I am looking at upgrading my current Burris FFII to the new Burris C4 system which comes with a custom calibrated reticle that automatically adjusts for elevation out to 650 yards. It also comes with a hand wind map that mounts on the scope and tells gives you a quick and easy reference provided you can estimate wind drift accurately. There are plenty of good scopes that will meet your requirements, you just need to pick one that meets your budget and needs.

As far as the Savage goes, I have no experience on 1,000+ yard shooting other than you will need a very high quality mildot scope and mount with plenty of elevation adjustment. Other than that it seems most of hitting at that range comes with lots practice and load development.

Good luck

 

[Art Eatman]

The first time I shot on my 500-yard range, the breeze from the left didn't seem all that much. I was shooting at a 22" steel plate. I guesstimated a Kentucky Windage hold of right at two feet to the left. A little low, but vertically centered. '06, 150-grain Sierra at about 3,100 ft/sec.

Stiff breeze, prairie dogs at 300 with a .223, about five to six inch hold for the wind.

9X or 10X is plenty good to 500 yards. Beyond that, I'll defer to those with experience.

 

[taliv]

i wouldn't really consider the swfa 10x an 'upgrade'.

get a bushnell HDMR or the newer ERS/XRS. it will be way more useful.

re: corrections, it all depends on how big your targets are.

a 3-9x would be a pretty big handicap in 3gun.

you can hit targets at 250 with irons. the trick is seeing them. sometimes it's challenging if you're the last shooter in the squad and the paint is all knocked off the target and there's not much contrast with the berm.

 

[kayak-man]

Thanks guy!

In retrospect, I probably could have asked the same question in a much simpler way, but I think I have the information I need now.

I'll look into those other scopes, and try not to make my rifles (or 3-9x scopes) do the jobs they were never intended for.

 

[DBR]

I can only comment on the AR with sight center line at about 2.5" above bore and in terms of defensive/hunting use:

For a 16" barrel rifle a 50 yd zero or about 2.5" high at 100yds will put shots +-2.5" POA from muzzle to about 220yds. It will shoot about 8-10" low at 300yds.

The best expanding 223/5.56 bullets have an expansion threshold of about 1800fps. This is about the velocity at 220yds. This is approx true regardless of the bullet weight from about 55gr to 70gr at NATO/5.56 pressure. Knock off about 30yds for SAAMI/223 pressure ammo.

A 20" barrel will make 223 pressure ammo about equal to 5.56 pressure ammo from a 16" barrel.

Therefore, I consider the 223/5.56 to be a 220yd rifle as far as bullet wound effectiveness/performance is concerned. With a 50yd zero out to 220yds just aim and shoot.

A 25yd zero makes no sense for any civy use. It puts the hit about 6-8" high at 100yds.

Target shooting is an entirely different proposition.

 

[mnhntr]

A good ballistic app will help you figure out your adjustments. Since you are new to long range shooting and not having anyone to teach you, this is the best way to learn. After a while you will gain the knowledge and skills to make it easier to figure on your own. I suggest more scope than a 10x for long range work. I use a 10x but it is what I am used to and it works for what I do.
As for the AR I use the 25m zero on my BUIS and that puts them on at 300m with my 55gr handloads and most 5.56 55gr ball ammo.

For a 16" barrel rifle a 50 yd zero or about 2.5" high at 100yds will put shots +-2.5" POA from muzzle to about 220yds. It will shoot about 8-10" low at 300yds.

The best expanding 223/5.56 bullets have an expansion threshold of about 1800fps. This is about the velocity at 220yds. This is approx true regardless of the bullet weight from about 55gr to 70gr at NATO/5.56 pressure. Knock off about 30yds for SAAMI/223 pressure ammo.

A 20" barrel will make 223 pressure ammo about equal to 5.56 pressure ammo from a 16" barrel.

Therefore, I consider the 223/5.56 to be a 220yd rifle as far as bullet wound effectiveness/performance is concerned. With a 50yd zero out to 220yds just aim and shoot.

A 25yd zero makes no sense for any civy use. It puts the hit about 6-8" high at 100yds.

Target shooting is an entirely different proposition

This makes no sense. I have no idea what ammo your using but most 55gr factory offerings are doing 1800fps at 400yds.
The 25m zero not 25yds is very good for predator hunting and 3 gun matches. So It is good for civilian use.

 

[DBR]

You are correct re velocity. Quick Target shows 55gr BT starting at 2925 hits 1800 at about 380yds. At 230yds it is going about 2250. I confused expansion threshold (1800) with fragmentation threshold (2200-2300).

Quick Target also shows that a 25yd (23 meter) zero will peak at about 8" above line of sight at about 100yds if sight line is 2.5" above bore. I don't see how this is useful for average civy use. A 50yd zero peaks at about 2" above sight line at 100yds and drops to 2" below sight line at 230yds.

 

[mnhntr]

Depends on what your use it for. Man size target doing 3 gun 8 in is in the A zone if you cut the target in 1/3 and for yote hunting 8in is an easy hold low on the belly at 100 and at 200-300 no hold over. For HD or SD 8in is nothing on a hostile.

 

[hartcreek]

You are using a Savage me a Remington 721 same caliber 30-06. Right now I an shooting 1000 m using a fixed power scope and it is a PITA so I too am looking to upgrade. I have posted here asking questions about the Leatherwood ART set up. Supposedly the new set up is slick just set the ballistic coefficient and sight it in and you are good to go out to 1000 m plus it also has mildots. I have my own 1000 m range and I use apple box size targets. Trying to avoid certain words here. I primanily want to use my Remington again for deer as logging has opened the area back up so I have some long range hunting opportunities is an area like I did 20 some years ago.

It just will give me another option over the blasted road hunters and brush beaters in my area.

 

[MistWolf]

The only way to find out is GO SHOOT THE RIFLE

 

[DBR]

mnhntr:

I'll take +-2" hits with point blank aim out to 220yds any day for what I use a 223/5.56 for. Each to his own I guess.

I know I can get dead on at 300yds with an 8" hold over and 300yds is realistically about the limit for 223 bullet terminal performance.

 

[mnhntr]

DBR I hear ya its all personal preference. I was Infantry in the Army so its what I am used to. I actually have my BUIS sighted this way but my hunting/3 gun AR has a 3x9 Nikon P223 on it along with a 45* offset red dot so the sights hardly see use anyways.

 

[cactus02]

I would look at the Millet sight web pages for 30-06 data try using 308 data (very similar)
http://www.millettsights.com/resources/shooting-tips/ballistic-data-cards/

 

[kayak-man]

Thanks again guys!

DBR: Thanks for the info regarding expanding ranges of .223/5.56. Its definitely good to know how far I can push that cartridge and still get the expansion.


Update: I was talking to one of the paramedics on my shift that's also a gun nut, and he made a couple really good points, mainly that I'm making the assumption that I need a scope to shoot a 30-06 out to a 1000 yards, but iron sights will work, and that the only way I'll know for sure is to actually shoot my rifle. I'm starting to think that the scope I have on there will work for now, and when I start to get the hang of it, then I can upgrade to something else, but at first, the money may be better spent on ammo.