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# Bullet drop compensation dials (BDC dials)

#29
05-11-2006, 07:01 PM
 Platinum Member Join Date: Feb 2005 Location: USA Posts: 2,598
Re: Bullet drop compensation dials (BDC dials)

There are not two kinds of minutes of angle. A circle is divide into 360 degrees and each degree is divided into 60 minutes so one minute of angle is 1/60 of one degree and this equates to 1.0472" of angle at 100 yards.In other words if you drew a straight line and a secound line that angeled away from the straight line by one minute of angle then at 100 yards they would be 1.0472" apart not 1" if you are useing minutes of angle there is only one.
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range it,check the wind, dial in correction, aim and only one shot

#30
05-11-2006, 08:10 PM
 Platinum Member Join Date: Dec 2001 Location: Mukilteo, WA Posts: 1,092
Re: Bullet drop compensation dials (BDC dials)

I agree. If a scope says MOA it should be assumed 1.047" @ 100 until measured otherwise. That's not to say there aren't 1" @ 100 scopes (by design or not). I think US Optics will build you one in SMOA, but it'll be labeled SMOA. Checking "the company line" for a few manufacturers, for USO MOA is MOA, Leupold when listing both MOA and inches uses actual MOA and from what I can tell from Nightforce they do as well (they say a 2 MOA reticle is "approximately 2" at 100 yds).

Every ballistic program I've used (that doesn't have an input to adjust it) uses MOA = 1.047" @ 100.

All that said, measuring is the only way to be sure (your particular scope might not be either exactly).
#31
05-11-2006, 11:27 PM
 Platinum Member Join Date: Sep 2004 Location: on the rifle range in Utah Posts: 2,704
Re: Bullet drop compensation dials (BDC dials)

I knew they were going to give you the run around.

I asked the very same q's to Art Pejsa (self proclaimed ballistics guru), Sierra techs, Berger, Exbal/perry, and several others about a year ago and got the old "we make the programs the way we make them" routine. <font color="red">None of these guys will even admit that their precious programs all make you shoot a couple clicks low at 700+ yards and as much as a minute and a half low at 1k depending on bc and velo. </font>

Same thing goes for when I asked them about their stupid uphill downhill zero features that don't move your second bullet/line of sight crossing further out with an angle shot!

C'mon program writers. This is simple and could easily be remedied.

BTW, we should probably take this topic to another subsection and start another thread so people won't loose out on this valuable info. Otherwise, they might attempt to shoot a deer or something at 1k and use their straight info from Exbal and shoot the legs off an animal.
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#32
05-11-2006, 11:35 PM
 Platinum Member Join Date: Sep 2004 Location: on the rifle range in Utah Posts: 2,704
Re: Bullet drop compensation dials (BDC dials)

[ QUOTE ]
There are not two kinds of minutes of angle. A circle is divide into 360 degrees and each degree is divided into 60 minutes so one minute of angle is 1/60 of one degree and this equates to 1.0472" of angle at 100 yards.In other words if you drew a straight line and a secound line that angeled away from the straight line by one minute of angle then at 100 yards they would be 1.0472" apart not 1" if you are useing minutes of angle there is only one.

[/ QUOTE ]

That is correct. But what we are trying to say is that the ballistic programs aren't giving you info that directly transcribes to what your scope actually does.

YOur scope moves the reticle 1" at 100 yards and not 1.0472" which is what the program is telling you to move the turret. So when you get out there aways, that .0472 starts to add up and becomes prevalent. Rather than have everyone send in their scopes to be retro-fitted to move the actual 1.0472, it is easier to have the hackers write a program that actually <font color="red"> calculates in the same language your scope talks! </font>

Does this help clarify?
__________________
Find it
Range it
Click it
Pull it
Dump it

If it's not far, it's boring.
#33
05-11-2006, 11:39 PM
 Platinum Member Join Date: Sep 2004 Location: on the rifle range in Utah Posts: 2,704
Re: Bullet drop compensation dials (BDC dials)

[ QUOTE ]
I agree. If a scope says MOA it should be assumed 1.047" @ 100 until measured otherwise.

[/ QUOTE ]

If you assume that you will be guaranteed to have nothing but frustration trying to make things work out.
__________________
Find it
Range it
Click it
Pull it
Dump it

If it's not far, it's boring.
#34
05-12-2006, 01:59 AM
 Platinum Member Join Date: Dec 2001 Location: Mukilteo, WA Posts: 1,092
Re: Bullet drop compensation dials (BDC dials)

That's why I say measure. I know I'm not going to guarantee everybody's scope is exactly 1.00". Are you?
#35
05-12-2006, 05:33 AM
 Platinum Member Join Date: Feb 2005 Location: USA Posts: 2,598
Re: Bullet drop compensation dials (BDC dials)

[ QUOTE ]
[ QUOTE ]
There are not two kinds of minutes of angle. A circle is divide into 360 degrees and each degree is divided into 60 minutes so one minute of angle is 1/60 of one degree and this equates to 1.0472" of angle at 100 yards.In other words if you drew a straight line and a secound line that angeled away from the straight line by one minute of angle then at 100 yards they would be 1.0472" apart not 1" if you are useing minutes of angle there is only one.

[/ QUOTE ]

That is correct. But what we are trying to say is that the ballistic programs aren't giving you info that directly transcribes to what your scope actually does.

YOur scope moves the reticle 1" at 100 yards and not 1.0472" which is what the program is telling you to move the turret. So when you get out there aways, that .0472 starts to add up and becomes prevalent. Rather than have everyone send in their scopes to be retro-fitted to move the actual 1.0472, it is easier to have the hackers write a program that actually <font color="red"> calculates in the same language your scope talks! </font>

Does this help clarify?

[/ QUOTE ]

I agree. I just wanted to clear up the cofussion about the two,apparently I was not clear enough.I did not intend to infer that all scopes adjusted in moa.Some scopes are advertised to have adjustments of 1/8" or1/4" adjustments and others claim to adjust in 1/8 or 1/4 moa at 100 yards.
I also agree that actual shooting at distance is the only way to know for sure.This discrepancy is why many find that thier drops are off when they shoot to verify.
__________________
range it,check the wind, dial in correction, aim and only one shot

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