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build me a drop chart #5433930 11/20/14 09:43 PM
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Buzzsaw Offline OP
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never was much of an engineer or ballistician so here is what I need,

6.5, 140gr Berger VLD Hunting BC: .612 (G1)
2900FPS

Show me two things, an MOA drop chart.

POI chart with a 200 yard zero, re; dead on at 50 yards, 2.5" high at 100yrds, 3.5" high at 300yards, But how can this be a 200 yd zero?

My BDC dial is set at 200yd zero but hits 3" high at 100, my dove sized brain cant make sense of this, what am I missing??? No, I'm not drunk, just sound like it

http://i122.photobucket.com/albums/o257/...p;1416519649985


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Re: build me a drop chart [Re: Buzzsaw] #5433933 11/20/14 09:44 PM
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sorry here is a picture



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Re: build me a drop chart [Re: Buzzsaw] #5433957 11/20/14 09:53 PM
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HHUUMMMM, what to write, what to write, I got nothing.
Re: build me a drop chart [Re: Buzzsaw] #5433969 11/20/14 09:57 PM
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Need height over bore of the scope (measure center of bore to center of scope tube.

Re: build me a drop chart [Re: Buzzsaw] #5433993 11/20/14 10:06 PM
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Re: build me a drop chart [Re: Buzzsaw] #5434004 11/20/14 10:14 PM
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This image should help with your "why is my 200 yard zero also my 50 yard zero" and the "why am I high at 100" questions, as best as I understand your questions. (except you should be low at 300 vs high as you indicated in your email)



Last edited by howabouttheiris; 11/20/14 10:15 PM.
Re: build me a drop chart [Re: Buzzsaw] #5434008 11/20/14 10:15 PM
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What program is that ^


HHUUMMMM, what to write, what to write, I got nothing.
Re: build me a drop chart [Re: Buzzsaw] #5434012 11/20/14 10:17 PM
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JBM Ballistics... great calculator for trajectory/wind/moving-target-leads/transonic-boundaries/etc...

http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

Re: build me a drop chart [Re: Buzzsaw] #5434164 11/20/14 11:55 PM
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Is your Swaro in MOA or in 1/4"? There is a difference.


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Re: build me a drop chart [Re: ChadTRG42] #5434274 11/21/14 12:53 AM
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Hmmmm Scopes are not adjustable in inches. Although if set at 100 yards 1/4MOA is approximately 1/4".

The reticle on the scope is either an indication of MOA or MIL. Adjustments are in fractions of one of these. Typically 1/4MOA or 1/10MIL. (or finer adjustments for high end target scopes).

Re: build me a drop chart [Re: howabouttheiris] #5434321 11/21/14 01:27 AM
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Originally Posted By: howabouttheiris
Hmmmm Scopes are not adjustable in inches. Although if set at 100 yards 1/4MOA is approximately 1/4".

The reticle on the scope is either an indication of MOA or MIL. Adjustments are in fractions of one of these. Typically 1/4MOA or 1/10MIL. (or finer adjustments for high end target scopes).



There are some scope makers that say MOA but it truly is IPHY. There are also some scopes that are true IPHY. which is different than moa, by a bit.

Walter


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Re: build me a drop chart [Re: Wburke2010] #5434352 11/21/14 01:43 AM
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Originally Posted By: wburke2010
Originally Posted By: howabouttheiris
Hmmmm Scopes are not adjustable in inches. Although if set at 100 yards 1/4MOA is approximately 1/4".

The reticle on the scope is either an indication of MOA or MIL. Adjustments are in fractions of one of these. Typically 1/4MOA or 1/10MIL. (or finer adjustments for high end target scopes).



There are some scope makers that say MOA but it truly is IPHY. There are also some scopes that are true IPHY. which is different than moa, by a bit.

Walter


4.7% difference between MOA and IPHY, which matters depending on distance and the size of the target.

Buzz,

Set it for a true zero at 100 yards, then use the chart to generate a correction for the distances that will really be shot. Then go shoot those distances to obtain an true reading of the scope setting for each distance. Scopes can do odd things that do not necessarily match the charts, especially hunting scopes. Also, check in different temperatures as ammo velocity will change with the ambient temps. If you have a "smart" phone, ballistic software/apps can be downloaded for $10 or less. Some even will pick up local weather to automatically correct for local conditions.

Re: build me a drop chart [Re: jeffbird] #5434372 11/21/14 01:50 AM
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Originally Posted By: jeffbird
Originally Posted By: wburke2010
Originally Posted By: howabouttheiris
Hmmmm Scopes are not adjustable in inches. Although if set at 100 yards 1/4MOA is approximately 1/4".

The reticle on the scope is either an indication of MOA or MIL. Adjustments are in fractions of one of these. Typically 1/4MOA or 1/10MIL. (or finer adjustments for high end target scopes).



There are some scope makers that say MOA but it truly is IPHY. There are also some scopes that are true IPHY. which is different than moa, by a bit.

Walter


4.7% difference between MOA and IPHY, which matters depending on distance and the size of the target.

Buzz,

Set it for a true zero at 100 yards, then use the chart to generate a correction for the distances that will really be shot. Then go shoot those distances to obtain an true reading of the scope setting for each distance. Scopes can do odd things that do not necessarily match the charts, especially hunting scopes. Also, check in different temperatures as ammo velocity will change with the ambient temps. If you have a "smart" phone, software/apps can be downloaded for $10 or less that will correct for difference in air density, wind, and even powder velocity differences once you document them.


Bingo! That is the best to do with any scope.

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Re: build me a drop chart [Re: Buzzsaw] #5434462 11/21/14 02:50 AM
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These guys have handled most of it.

I will illustrate one more thing. Shoot paper at 10 yards. POA on a 1/4" dot. Where will your bullet impact? Below the dot you aimed at, right? That is sight offaet. You aiming device (scope) is sitting between 1.5" and 2.25' above the bore. The offset is why you have to hold OVER at 50 yards from a 100 yard zero, same as you have to hold OVER at 200 yards. They just happen to match.

I've had to shoot 1 MOA at 7 yards. Yes, 7. The correction is dial impact UP 6.2 Mil, which happens to be the same correction for 850 yards.


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Re: build me a drop chart [Re: Buzzsaw] #5434525 11/21/14 03:23 AM
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It's hard to understand why this is all so hard to understand.
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Re: build me a drop chart [Re: RiverRider] #5434585 11/21/14 03:49 AM
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Originally Posted By: RiverRider
It's hard to understand why this is all so hard to understand.
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Yup.

But when I have guys at the range I have a dry erase board that I can draw pictures on. Makes it "click" much faster.


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Re: build me a drop chart [Re: Buzzsaw] #5434634 11/21/14 04:16 AM
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Btw Buzz,
How about some details on the 6.5 Wby?
Very nice looking rifle.

Re: build me a drop chart [Re: Buzzsaw] #5434702 11/21/14 05:51 AM
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That chart posted above looks right, very close to the one I use for the same bullet started at 2910 from a 6.5-284. Works well with mine out to 790 yards which is as far as I have taken it so far.

Good looking rifle


lf the saying "Liar, Liar your pants on fire" were true
Mainstream news might be fun to watch
Re: build me a drop chart [Re: Buzzsaw] #5436098 11/22/14 01:00 AM
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Jeff,
It's a Mcwhorter 6.5 Weatherby. Borden Timberline, Jewell, Hart, 5-25X50 Swaro Z-5 plex and of course the McMillan. Gun shoots lights out with the 140 VLD Hunting bullet, think I may try the JLK bullet too. No recoil and hits hard.

I had them put a BDC turret on the Swaro as you can see (I fell for all the hunting shows BDC). I've never run a true BDC before, just sighted dead on at 100yd, ran a chart like the one above and dialed elevation and held wind when shooting F-Class. This is a hunting rifle, so I went BDC.

I think what is driving me crazy is when I hold dead on at 100, my cold bore shot is right at 2.5" high. From what my little brain tells me, It is not set at true 200 zero. According to the chart above it should only be 1.5" high. I think mcwhorter did not re-set the turrets when they sighted it in.

My plan is after the holidays, to buy JG a case of his favorite beverage and invite myself out to his range to shoot at all ranges to confirm and re-set turrets if needed. JG hint hint

Thanks for all the great stuff above, again, I am amazed at the knowledge ya'll have and share.


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Re: build me a drop chart [Re: Buzzsaw] #5436245 11/22/14 02:29 AM
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A case of off-road diesel. That's what I'm going through mostly these days. Just ask Judd, he's seen evidence...


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Re: build me a drop chart [Re: Buzzsaw] #5436828 11/22/14 02:49 PM
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Buzz,
Is it a necked down 270 Wby?
What is the approximate load and velocity with the 140's?

Re: build me a drop chart [Re: Buzzsaw] #5436874 11/22/14 03:33 PM
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IRRC they are using a 257 WBY necked up as the parent case. Saw that info on the Mcwhorter web page a couple years ago


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Mainstream news might be fun to watch
Re: build me a drop chart [Re: kmon11] #5443465 11/26/14 02:21 AM
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Originally Posted By: kmon1
IRRC they are using a 257 WBY necked up as the parent case. Saw that info on the Mcwhorter web page a couple years ago


True, .257 Weatherby necked up a bit, 67.5 grains H-1000, 3048fps, no pressure with the 140's. Tim Mcwhorter said he likes the 270 Weatherby as a parent, but Alan Roving likes the .257. They have Redding make die sets for them.

Just got back from my deer lease, I had a fat axis doe at 612 yards yesterday, she was on the wrong side of the fence so I didn't shoot, but I had a very steady hold. maybe next trip down in December we'll see


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Re: build me a drop chart [Re: J.G.] #5443468 11/26/14 02:22 AM
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Originally Posted By: FiremanJG
A case of off-road diesel. That's what I'm going through mostly these days. Just ask Judd, he's seen evidence...


Is this a special oil for your ram? Where can I find it?


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Re: build me a drop chart [Re: Buzzsaw] #5443478 11/26/14 02:31 AM
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Originally Posted By: Buzzsaw
Originally Posted By: FiremanJG
A case of off-road diesel. That's what I'm going through mostly these days. Just ask Judd, he's seen evidence...


Is this a special oil for your ram? Where can I find it?


That was a joke. Off road diesel is used for tractors and excavation equipment. It's tax free and you need a form from the state Comptroller to buy it.


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