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Old April 08, 2018, 18:07   #1
Impala_Guy
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Question on scope BDC reticles

How effective are these? I normally zero a .30 cal. rifle at 100 yards leaving shots a few inches high, and thus theoretically at least, I should be about dead on at 300 yards. How much does this affect the accuracy of the 400, 500, and 600 yard hash marks? I assume that since you are basically shooting upwards at a slight angle that the bullets forward velocity and AOA must generate some kind of lift that affects the bullets natural rate of drop due to the acceleration of gravity until the bullet arc peaks, no?

In other words, if I dont zero dead on at 100 yards, is the reticle basically useless for elevation holdover? Maybe a dumb question since I should use the reticle range marks to begin with but old habits developed before we had these good toys are hard to break.
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Old April 08, 2018, 18:48   #2
Goose52
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I have a few scopes with BDC hashmarks/dots (for .22 long rifle, .223, and .308). It is assumed that you will sight in the rifle at a range recommended by the scope manufacturer. As you said, the old rule of thumb to sight in 2 or 3 inches high at 100 does not apply in this case - you're supposed to sight-in at the set range and use the hashmarks for other distances.

Once sighted in are they exact at the other distances? Generally - no. The scope manufacturer calibrated the scope using a particular load out of a particular rifle and barrel length. When using other loads, out of other barrel lengths, with bullets of varying BCs, and with varying velocities, you are going to get varying results down range.

Having said the above, I have found that the hashmarks generally DO get me close enough to the target that I can call the shot and hold-off accordingly. We have some steel at 500 at my club and I can generally either hit the steel, or get close enough, using the 500 hashmark with most of my .223 and .308 loads.

FWIW
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Old April 10, 2018, 21:34   #3
skeeterbay
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This is been my experience using them. For large game, people sized paper targets or steel you will probably get hits somewhere on the target at medium ranges if your loads are in the ball park of "normal" velocities for that caliber.

I and a son or two use them on several hunting rifles we have. I shoot them with that rifles hunting load over a chrono and then at actual distances. I then do up a cheat sheet and fix it to the stock or the scope. It's not so important on a 300 yard moose or deer rifle but my favorite coyote rifle and load is off substantially from the manufactures chart at distance. Mainly because I load down my yote rounds to minimize pelt damage. Also because I use a short barrel.

Some of my rifles like my the 9.3X62mm are short range moose guns. I just sight them in at 200 yards and know the drop at 250 with my load. I don't see the worth in a BDC scope for those type of cartridges.
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Old April 11, 2018, 06:55   #4
kotengu
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Quote:
Originally Posted by Goose52 View Post
I have a few scopes with BDC hashmarks/dots (for .22 long rifle, .223, and .308). It is assumed that you will sight in the rifle at a range recommended by the scope manufacturer. As you said, the old rule of thumb to sight in 2 or 3 inches high at 100 does not apply in this case - you're supposed to sight-in at the set range and use the hashmarks for other distances.

Once sighted in are they exact at the other distances? Generally - no. The scope manufacturer calibrated the scope using a particular load out of a particular rifle and barrel length. When using other loads, out of other barrel lengths, with bullets of varying BCs, and with varying velocities, you are going to get varying results down range.

Having said the above, I have found that the hashmarks generally DO get me close enough to the target that I can call the shot and hold-off accordingly. We have some steel at 500 at my club and I can generally either hit the steel, or get close enough, using the 500 hashmark with most of my .223 and .308 loads.

FWIW
This. I have them and prefer them. But you have to understand what they are and what their limitations are.
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Old April 11, 2018, 10:39   #5
hagar
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There are so many variables, temperature, altitude, humidity, bullet weight and type that there is no way these can be accurate for all conditions.

I use the shooter App on my phone to give me the clicks, and that works well, even at 1000 yards. You have to know the velocity of your load, and you have to input wind speed and direction, altitude, temp and humidity.

Let me know for what bullet, I can give you some calculations.
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Old April 11, 2018, 11:49   #6
sniperdoc
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They are set for certain loads and bullet weights.
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