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Vortex Viper PST 4-16 FFP - do I need a canted base?
#5937353
09/20/15 05:26 PM
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just heard from a friend that there will be a long distance shoot next Saturday. I can't participate, but got to thinking and calculating. Without a canted base, how far out will my scope allow for adjustments. It's the mil/mil version. If I'm sighted in for 100 yards, my data suggests that I can't adjust out to 600 yards, which would be the max range for the shoot. The bullet I'm shooting these days is the 100 gr Nosler BT, which I know isn't the bullet to use, but would be the bullet if I was going to shoot on Saturday.
It seems that the guy putting on the shoot is planning to build a formal range with a max distance of 600. Somewhere around Marlin, Tx.
Not my monkeys, not my circus...
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Re: Vortex Viper PST 4-16 FFP - do I need a canted base?
[Re: 603Country]
#5937455
09/20/15 06:59 PM
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QuitShootinYoungBucks
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https://web.archive.org/web/20170223065011/http:/www.rrdvegas.com/silencer-cleaning.html
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Re: Vortex Viper PST 4-16 FFP - do I need a canted base?
[Re: 603Country]
#5937587
09/20/15 08:37 PM
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Not my monkeys, not my circus...
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Re: Vortex Viper PST 4-16 FFP - do I need a canted base?
[Re: 603Country]
#5937591
09/20/15 08:40 PM
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J.G.
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Zeroed at 100 yards, shooting a 140 gr @2800 fps MV you need 3.6 Mils to get to 600 yards. If you are already zeroed on a "0" MOA base, at 100 yards you have plenty of travel left to get to 600. edit: Sorry, just notcied the bullet you're using. I need to know the BC and the MV to give you a predicted correction. At any rate, you still have enough travel left to get to 600 yards.
Last edited by FiremanJG; 09/20/15 08:42 PM.
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Re: Vortex Viper PST 4-16 FFP - do I need a canted base?
[Re: 603Country]
#5937618
09/20/15 08:54 PM
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With ballistics ae. It has nosler 100 grain partition at 3.6 miles at 600. velocity at 3200
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Re: Vortex Viper PST 4-16 FFP - do I need a canted base?
[Re: 603Country]
#5937620
09/20/15 08:55 PM
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J.G.
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Just ran it with these values:
MV 3000 fps BC .350 5 mph wind 3 or 9 o'clock
200 yards elevation .3 wind .2 300 yds elev 1.0 wind .4 400 yds elev 1.8 wind .5 500 yds elev 2.7 wind .7 600 yds elev 3.8 wind .9
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Re: Vortex Viper PST 4-16 FFP - do I need a canted base?
[Re: 603Country]
#5937646
09/20/15 09:18 PM
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MV is right. Thanks for clearing it up for me.
Not my monkeys, not my circus...
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Re: Vortex Viper PST 4-16 FFP - do I need a canted base?
[Re: 603Country]
#5938087
09/21/15 01:19 AM
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QuitShootinYoungBucks
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I ran it on JM and got close to those numbers when I thought it was a .243. Glad to know I was doing it right!
https://web.archive.org/web/20170223065011/http:/www.rrdvegas.com/silencer-cleaning.html
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Re: Vortex Viper PST 4-16 FFP - do I need a canted base?
[Re: 603Country]
#5938088
09/21/15 01:19 AM
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ChadTRG42
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Let's calculate how much travel you have. The specs on the Vortex Viper PST 4-16 FFP show 21 MRAD, so 21 mils of total travel. If you have a zero canted base, your zero should be really close to the middle of the 21 mils, so about 10.5 mils. You have about 10.5 mils of available travel.
The easy way is to zero the rifle at 100 and zero the turrets. Then simply dial up and count how many mils you have until the turret stops. This would be your actual adjustment up. Plus, you can use the reticle to hold higher with another 10 mils, if needed. If you knew your hold overs, you could not even dial, and just use the reticle, too.
It takes me 8.3 mils to 1K with my slower 6.5x47. So, the 10+ mils is plenty to get out as far as you want.
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Re: Vortex Viper PST 4-16 FFP - do I need a canted base?
[Re: 603Country]
#5938115
09/21/15 01:28 AM
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ChadTRG42
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Also, if you added a 20 moa canted base, here's what it would come out to. A 20 moa base equals about 6 mils. So, you would add 6 mils to your 10.5 mils of up, and get about 16.5 mils of total upward travel. One the back side, you would only have about 4.5 mils of down adjustment (~15 moa). It should have enough clearance, but it's getting close to the minimum amount. I keep at a minimum 10 moa of down as a cushion. The math works great, but in real life, not everything lines up perfect. Between the rings, base and action, if anything is off, you may not have enough down to get a 100 yard zero. I see guys do this often, thinking they "need" a 20 moa base, but don't have the internal adjustment inside the scope for a 100 yard zero with the canted base.
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