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10 MOA for 7mm Rem Mag

 
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  #8  
Old 11-04-2008, 10:46 AM
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Location: Northern Michigan
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Re: 10 MOA for 7mm Rem Mag

There won't be any wondering with a 10 as it is probably the safest bet.
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  #9  
Old 11-05-2008, 11:04 AM
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Join Date: Oct 2007
Posts: 880
Re: 10 MOA for 7mm Rem Mag

Quote:
Originally Posted by Billinsd View Post
So, say a 180 grain berger drops 300 inches at 1000 yards, that is 30 MOA, right? And if my scope has say, 65 MOA, figure you divide in half and have say 32 MOA with a zero MOA base, right? So by adding a 10 MOA scope base that would give me another 100 inches of play at 1000 yards, right?
Bill
First off.....big difference between bullet drop and bullet path!

Example: berger 180 vld @ 3000fps (1300 ft @ 30degrees) 100 yard zero

Bullet Drop.......274 inches at 1K.

Bullet path......237 inches at 1K.

You will need to adjust 23 3/4 min to go from 100 to 1000, NOT 27 1/2 min

Big , Big difference.

As for your question...you will have no problem with standard ring/base setup if you use a Leupod or Nightforce. This I know. If you are using another brand, check the adjustment range of those scopes before you buy.

Also, don't automaticaly assume that your scope will be at the middle of its adjustment range when it is zeroed at 100 yards. I have seen many times the need for the scope to be cranked to near the end of its adjustment range just to get on at 100. That may not leave you enough adjustment to get to 1K.
I would say go wit the 10 MOA setup, but be sure to lap in the rings, or have someone do it for you.

Good Luck.

Last edited by 4xforfun; 11-05-2008 at 11:08 AM.
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  #10  
Old 11-06-2008, 10:25 PM
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Join Date: Sep 2007
Posts: 60
Re: 10 MOA for 7mm Rem Mag

Quote:
Originally Posted by 4xforfun View Post
First off.....big difference between bullet drop and bullet path!.
Thanks for the post. Would you mind explaining bullet path?
Quote:
Originally Posted by 4xforfun View Post
Also, don't automaticaly assume that your scope will be at the middle of its adjustment range when it is zeroed at 100 yards. I have seen many times the need for the scope to be cranked to near the end of its adjustment range just to get on at 100. That may not leave you enough adjustment to get to 1K.
Thanks, I did not know that.
Quote:
Originally Posted by 4xforfun View Post
I would say go wit the 10 MOA setup, but be sure to lap in the rings, or have someone do it for you.
So, do you mean lap the rings so I can get the gun to shoot to 1K, or to relieve the pressure points so the gun will shoot more consistently?

Also, would you mind posting the same data for 168 grain 7mm mag Bergers?

Thanks
Bill
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  #11  
Old 11-07-2008, 10:26 AM
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Join Date: Oct 2007
Posts: 880
Re: 10 MOA for 7mm Rem Mag

Quote:
Originally Posted by Billinsd View Post
Thanks for the post. Would you mind explaining bullet path?Thanks, I did not know that.So, do you mean lap the rings so I can get the gun to shoot to 1K, or to relieve the pressure points so the gun will shoot more consistently?

Also, would you mind posting the same data for 168 grain 7mm mag Bergers?

Thanks
Bill
Drop: this is the amount the bullet drops at a given distance. the bullet leaves the gun level with the horizon, and will start to drop right away. We are not concerned with a zero, just the actual amount the bullet drops.

Bullet path: This is the path the bullet takes when zeroed at XXX yards.


Lets assume your 168 (3000 fps) is zeroed at 300 yards, and your scope height is 1.9 inches above the bore. The bullet leaves the bbl at an upward angle, crosses your line of sight on an upward path at about 25 yards. and is on its way back down when it crosses your line of sight again at 300 yards. at around 190 yards the bullet is actualy 4 inches high. Now, although your bullet is dead on at 300, the actual drop of the bullet is actualy 19 1/4 inches.

Now with the same setup, but at 1000 yards, without dialing up....just leaving the gun zeroed at 300 yards. Again, you bullet crosses your sight line on the way up at around 25 yards. It again crosses it on the way back down at EXACTLY 300 yards (300 yard zero) and the bullet will hit 214.54 inches low at 1000 yards. BUT.......you bullet actualy dropped 283 inches, its just that you had the gun pointed at an upward angle to your line of sight.

bullet path....-214.54 inches = 21 1/2 min of adjustment to hit dead on at 1 K.

Rings don't always line up exactly with each other, which binds on the scope tube when you tighten up the rings. Lapping rings is very important when you are using tapered rings-basses. Basicly, the lapping kit includes a steel rod, either 1 " or 30 MM, and some lapping compound. You install your basses and rings on the gun, take the top half of the rings off, put a little compound on the bottom rings, and slide the rod back and fourth untill the rod makes good contact with the rings. You are basicly sanding down the inside of the rings smooth and strait to prevent binding on the scope.

Also, I have seen factory guns where the holes for the scope bases are not exactly on center, or the bbl has a slight bend(we are talking thousands of an inch here, not a big amount). You can find the center of the adjustment on the scope, mount it on the gun, and be 4 feet off at 100 yards!!

Hope this helps. I did it in a hurry and deer gun season starts at noon, so i probably made some typos, spelling errors, among other things.

You guys feel free to correct me and I will check things over later.

Good luck
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  #12  
Old 11-07-2008, 10:41 AM
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Join Date: Sep 2007
Posts: 60
Re: 10 MOA for 7mm Rem Mag

Thanks. I've always refered to bullet path as the drop. I see what you are talking about, thanks.

Yes, I knew about lapping the scope rings. I've never done it though.

I still do not undertand why lapping is more important with tappered rings or bases?

So if the scope base holes are not centered or the barrel is slightly bent would lapping the rings help? If so how would it?

How would I measure to see if the scope base holes are centered and how can I make sure the scope is perfectly square on the rifle?

Thanks for your help, I understand about getting out and hunting. Take your time answering when you have time.

I really appreciate the help!!!!!!

Thanks
Bill
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  #13  
Old 11-07-2008, 08:14 PM
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Join Date: Oct 2007
Posts: 880
Re: 10 MOA for 7mm Rem Mag

The only thing lapping the rings does is protect your scope. Nothing more.

If the holes for the scope bases are crazy off you can either have a smith fill em and re drill em, or get some adjustible bases, like the ones made by Leupold. They have opposing screws on the back of the bases (one piece base) to help adjust l-r. Just center up your scope's adjustment and get the basic zero with the screws. Something tells me that they are called S-T-D bases, but I am not sure. I have a few guns with them, and they are very reliable.

As far as a bent bbl, replacement is the only cure. I have never herd of a tube so far off that it was impossable to fix with adjustible basses for L & R and shims- tapered bases for the U-D. Of course, I don't get out much!!

Good luck!!
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  #14  
Old 11-07-2008, 09:40 PM
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Join Date: Sep 2007
Posts: 60
Re: 10 MOA for 7mm Rem Mag

Thanks a lot, I appreciate it.

So, is there anyway to physically, and practically measure whether the scope mount screws are off center and if the barrel is bent?

Thanks
Bill
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