Rifle Scopes Hold over at 300 yards with a U.S. Optics SN-3

[Wedgeman]

I am shooting a M1A with a U.S. OPTICS SN-3 1.8-10 POWER SCOPE.
It is sighted in at 100 yards, dead-on. Iam shooting M118 Lake city Match Ammo 173 grain ammo. I went to a 300 yard range last weekend for the first time, never shot past 100 yards. What is my hold over at 300 yards with this ammo? My reticle is a MOA Scale type 1. I am new to long range shooting and just starting shoot at longer ranges. The HASH MARKS on my scope are 2 MOA Spacing, I just do not want to start turning my knobs and lose my 100 yard zero as I most of the time shoot only 100 yards. But I am reading about hold over on these scopes and want to learn, My rifle has a Med./Match Barrel. I only shoot this Type of Ammo out of this rifle. So how many hash marks do I hold over at 300 yards? I am a Rookie at this so please any info will help, I want to learn more about longer range shooting. Thanks

 

[Lowlight]

Re: Hold over at 300 yards with a U.S. Optics SN-3

If you reset your knobs to zero, you cannot "lose" your 100 yard zero...

But dialing or holding try 5 MOA

 

[Ffej]

Re: Hold over at 300 yards with a U.S. Optics SN-3

Here is some info from the MST-100's BDC knob (using 173gr M118 ammo):

100 - 0
200 - 2 MOA
300 - 5 MOA
400 - 8 MOA
500 - 12 MOA
600 - 16 MOA
700 - 20.5 MOA
800 - 25 MOA
900 - 31 MOA
1000 - 37.5 MOA

This should get you on target at each distance and you can fine tune it from there.

To answer your question, based on the data above, you should hold 2.5 hash marks below the center of the reticle.

 

[Ffej]

Re: Hold over at 300 yards with a U.S. Optics SN-3

Franks's right about the zero. If you haven't already, loosen the top allen screw (or screws if you have the EREK) and turn the knob so the "0" aligns with the center reference line. That will set your knob to your rifle's zero.

 

[Topstrap]

Re: Hold over at 300 yards with a U.S. Optics SN-3

Lots of variables to make a perfect chart but a reasonable guess would be about 2 1/2 to 3 hash marks if each mark is 2moa. Guessing your bullet is traveling about 2550fps and your scope is 2" above your bore it should get you in the ballpark.

You'll be much better off learning to crank on the scope though since that will benefit you in the future. That is what those numbers on the scope are for, keep track of where your zero is and crank down till it stops or gets firm without forcing the elevation know and see how many revolutions it takes, then come back up that amount back to your zero. The scope should do that reliably and you can always find it if you get lost. Then learn to use the elevation knob and a chart such as JBM to find your hold for your other distances. You'll be amazed how accurate that printout is and how many first round hits you'll be getting.

Good luck

Topstrap

 

[FLIGHT762]

Re: Hold over at 300 yards with a U.S. Optics SN-3

Good for you for wanting to learn to calculate hold overs. On a rainy day, when you have some time, go to : http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi and spend time learning how to use the free ballistic program.

You can print out, reduce and laminate your ballistic data. The program allows dual columns for MILS and MOA. It has a vast bullet library to reference. Go to the glossary to learn how to use the program. It's easy to use once you understand it.

 

[SLVGW360]

Re: Hold over at 300 yards with a U.S. Optics SN-3

I'll bet his issue is like mine when I started. Many of us were taught when we were young to get a good zero and then never touch those dials again.

It is OK, that scope and many like it these days will return to zero just fine. Try it and find out for yourself.

 

[Gregch44]

Re: Hold over at 300 yards with a U.S. Optics SN-3

Sounds like you are used to hunting scopes where you set your zero, leave it alone, and learn your holdovers. These scopes are made to dial, Set your turrent to zero, and learn to dial as well as use holdovers. No sense not using your gear to its potential.