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Discussion in 'Optics & Mounts' started by truevil1313, May 4, 2009.
Is a 15 MOA base a good idea for shooting 100-600 yards?
Probably be easier and cheaper to get a 20 MOA base. They are very common and it adds GREAT benefit to the overall travel of your scope.
Every bolt rifle I have has a 20 MOA base on them. Just gives you SO MUCH MORE that you can do for longer range shooting without maxing out your dials on your scope.
Thanks JD. I got a good 15 MOA base for almost nothing, but I don't completely understand why it works. I read a website that said a zero MOA base is good for 0-500 yards and a 20 is good for 600-1000 yards. But I shoot 100-600 yards. Anyway when I was looking at it I got so confused, the front sits lower than the back, and this seems backwards to me. If the scope is pointing down wont I have to crank the turret way up to get it to shoot 100 yards? See I am confused.
If the scope is pointing down, it forces your muzzle up to bring the cross hairs onto your target.
It all makes since now that I got everything mounted and zeroed. Heck at 100 yards my turret is almost bottomed out. Sure gives lots of room to adjust up for elevation.
Thanks for the help.
I would figure out POI at 300 with your base and then add that in to your scope so it is shooting that much high at 100 yards. Then you don't have to make as much movement as you go out.
Also now you need to make a drop chart for your prefered load. Here is the one I prefer to use. Hornady
Think of it in terms of the bullet as the bullet gets further away from the muzzle it drops as it goes creating the arch we see in ballistics charts. So to get the bullet on target at say 600 yard you have to elevate the muzzle but not the scope. Yes it can be confusing.
CPT thanks for the info. I already have the chart for my favorite load, but I have also done charts on every 150-175 grn load made by Winchester, Remington, Federal, and Hornady(just in case there ever is a SHTF, you never know what you will be able to find).
true - a couple of thoughts.
When you are dealing with optics, you have to remember that everything is MIRRORED. Your scope needs to go DOWN angle because your barrel needs to go UP angle. With a flat base, you would top out your scope adjustment unless you had a 65 MOA scope, as you work your way out.
I have suggested this before, but you are getting to the point where I REALLY, SERIOUSLY must suggest you get off the internet and do some real reading by some experts.
Ultimate Sniper by Maj. John Plaster ( retired ) is an invaluable source of real world knowledge and will help you understand several of these types of issues.
I have read it twice, am re-reading it again in my spare time, and I still learn / re-learn new stuff each time through. It made a world of difference in both my knowledge and my training.
Accurizing the Factory Rifle by Macpherson is a great beginner's guide into what makes a rifle shoot and what makes it shoot better. It's a bit dated by this day and age, but the core information is still quite valid and relevant. It's a good read and will give you some more insight into what affects accuracy and how it can be improved.
The problem with all the webforums that you are sourcing for information is that you have to remember the 40% rule of the Internet. Disregard about 15% of the top information and 25% of the low end information - then look you still have to find more than just one or two guys who are saying the same thing for it to even approach crediability.
You've exhausted the basic knowledge portion of Internet Gun Building 101 - now you need to get your hands on some real works, by some people who have set standards, so you can learn the why's to go with all the how's.
Thanks JD. I finish up with school this week, so will then go and find the books you recomended. I do want to know the "whys" that go with the "hows".
After trying 3 different book stores and searching the library's computer system, i came up empty handed on finding the books locally, so I just went ahead and ordered them. I guess they should be in next week. Thanks for the advice JD.
I think that you will find the reads worth your time and it will open up a whole different bag of questions for you in the future months.
Optic Base probably critical beyond 600 yards
You didn't mention what cartridge you shoot. Most 30 caliber cartridges will shoot to 600yards with less than 15 MOA of adjustment. In that case a 15 MOA base is not important.
I don't shoot an AR15 but the 0.223 55gr has about a 0.2BC and MV of 3,200 fps. 600 yds require about 21 MOA, again not likely to need a base.
A 20 MOA base can be too much for some optics. My long distance optic has has 52 MOA in the up direction, only 12 MOA in the down direction. I can zero a 15 MOA base perfectly. I am 4 MOA short of being able to zero with 20 MOA base. With the 20 MOA base I shoot 4" high at 100 yards, and 0" high at 300 yards.
Your 15 MOA base will serve you well. Don't worry, you're not missing anything not having a 20 MOA base. It will probably be useless at up to 600 yards. But at 700+ yards with an AR you'll be glad you have it. Good luck.