Sighted in and zeroed a new Vortex Razor MRAD 34mm tube, 56mm obnective, today. Zero was repeatable shot after shot. We set up the long board and verified the plumb line against the reticle We dialed in 9 mil, 10 mil, and 5 mil at random and consistently shot .75" to 1.0" high. The only conclusion we can come to is the scope height is 2.875" above the bore centerline, and all my ballistic software was set for 1.5" Am I on the right track?
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Long Board Test
- Thread starter kobraken
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Rich Coyle
Well-Known Member
What rifle are you using where the scope is 2 7/8" above the bore?
velvetant
Well-Known Member
How far did you shoot?
How did you verify your exact distance?
How did you verify your exact distance?
If you are only shooting at 100 yards then "no" the scope height setting in your ballistic app has nothing to do with anything. You dial in 5 mils and should be able to check impact in the reticle at 5 mils; 9 mils or 10 mils or whatever, it should read in your reticle with that scope as the amount dialed. Since it's FFP, you can use any power.
As velvetant said- How did you check yardage to make sure it's exact? It's either the range, your zero is off, or your scope adjustments aren't true. That's why I always recommend a test of this nature.
As velvetant said- How did you check yardage to make sure it's exact? It's either the range, your zero is off, or your scope adjustments aren't true. That's why I always recommend a test of this nature.
UPDATE TO THE REQUESTS FOR MORE INFO
ruger Precision Rifle
LaRue scope mount #LT 845 listed as " 1.535" above the rail"
Verified target range with tape measure. 100 yds-- didn't trust range finder
Shot multiple zeros. Drew "X" at random and shot it repeatedly
I didn't really think it was the mount height but we ran out of ideas.
Keep the questions and ideas coming. Thanks guys!!!
ruger Precision Rifle
LaRue scope mount #LT 845 listed as " 1.535" above the rail"
Verified target range with tape measure. 100 yds-- didn't trust range finder
Shot multiple zeros. Drew "X" at random and shot it repeatedly
I didn't really think it was the mount height but we ran out of ideas.
Keep the questions and ideas coming. Thanks guys!!!
If you think all else is good, send the scope in to Vortex. 1" off over 10 mils of adjustment @ 100 yards would be 3.6% (unless my math is off) and that would be unacceptable to me, especially for this quality/price scope. I have scopes in the $200-$400 range that track true and have for years, or I wouldn't own them.
375fan
Well-Known Member
The 2.875 sounds high, even with the center of mount being 1.535 above rail. Open your bolt,take a set of calipers and and measure from center of scope to center of bolt (yes this a little crude method) I'm betting your more like 2.25ish above bore. Then change the number in your ballistic calculator and reshoot your test.
I will recheck the scope height this weekend when I get home.
I talked to Vortex-James- today. He was very helpful, and offered a couple of suggestions.
1. We did not adjust the focus to cleanup the paralax.
2. He suggested we loosen the scope mounting screws as we may have over tightened them
If neither of these suggestions correct the problem they said to return it and they would be happy to check it out.
I talked to Vortex-James- today. He was very helpful, and offered a couple of suggestions.
1. We did not adjust the focus to cleanup the paralax.
2. He suggested we loosen the scope mounting screws as we may have over tightened them
If neither of these suggestions correct the problem they said to return it and they would be happy to check it out.
Here is a picture of a 56mm obj scope in 1.375" rings, so your height in a higher mount does add up.
Again- changing the numbers in your app should not change anything if checking the scope's repeatability at 100 yards. Leave the app out of it and just crank the scope and shoot or read it in the reticle.
However, if you do not have the rings torqued properly it can interfere with the erector tube/adjustments and or parallax adjustment. You not relieving your sight picture of parallax certainly isn't helping either.
Again- changing the numbers in your app should not change anything if checking the scope's repeatability at 100 yards. Leave the app out of it and just crank the scope and shoot or read it in the reticle.
However, if you do not have the rings torqued properly it can interfere with the erector tube/adjustments and or parallax adjustment. You not relieving your sight picture of parallax certainly isn't helping either.
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el matador
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I don't understand how you're using the ballistic calculator in this situation. Normally you would use such a thing to determine the scope adjustments for shooting at distances beyond your sight-in range. At 100 yards you can just use some math and measure how much your point of impact should be moving. Since 1 radian is equal to the distance you're shooting at, simply divide that number by 1000 to get 1 milliradian (or 10,000 to get 0.1 mrad). 100 yards (3600 inches) divided by 1000 makes 3.6" per mrad. For scopes with 0.1 mrad clicks that equals 0.36" per click.
So from your zero if you come up 10 mrad you should be hitting 36" high on the tall target. 9 mrad = 32.4" and 5 mrad = 18". What were the actual measurements of your groups above the bullseye?
So from your zero if you come up 10 mrad you should be hitting 36" high on the tall target. 9 mrad = 32.4" and 5 mrad = 18". What were the actual measurements of your groups above the bullseye?
Ok--- I'm gonna tell on myself. I've been shooting rifles with cheesy scopes all my life. I even own a couple of decent scopes (MOA) with turrets. But I've never dialed a scope in my life. In my area a 200 yds shot ,(hunting) is about as far as it goes. I have made a couple of longer, 275 and 344 yds, on an elk in New Mexico. I used my BDC dots for those shots.( and guessed )
So, a MIL scope is new to me and I've got my head wrapped around it now. I love being able to dial in a range and if I do my part,score a hit.
El matodor---
I dialed the scope up 9 mil. I did the math, 3.6 x 9 = 32.4 "of rise at 100 yds. I'm also learning to use my ballistic app at the same time so I was using it as a backup to my calculator.
I actually shot 33.4" a difference of 1" thought this was odd, so we backed it down to 5 mil---3.6x5= 18" Shot 18.7 on that one, back up to 10 mil--3.6x10= 36"
and shot 36.8 on that
As a side note-- we shot these as 3 shot groups. We shot centerline and then dialed 1 mil left and 1 mil right (just learning to dial it ) and the shots tracked appropriately the correct offset.
So, a MIL scope is new to me and I've got my head wrapped around it now. I love being able to dial in a range and if I do my part,score a hit.
El matodor---
I dialed the scope up 9 mil. I did the math, 3.6 x 9 = 32.4 "of rise at 100 yds. I'm also learning to use my ballistic app at the same time so I was using it as a backup to my calculator.
I actually shot 33.4" a difference of 1" thought this was odd, so we backed it down to 5 mil---3.6x5= 18" Shot 18.7 on that one, back up to 10 mil--3.6x10= 36"
and shot 36.8 on that
As a side note-- we shot these as 3 shot groups. We shot centerline and then dialed 1 mil left and 1 mil right (just learning to dial it ) and the shots tracked appropriately the correct offset.
el matador
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Looking at your data we can calculate a total error of between 2.2% and 3.8% with an average of around 3%. Even the low number of 2.2% is higher than I would like to see in a high-end scope. Here's an article that talks about how to measure the distance accurately and a comparison of some expensive scopes: Tactical Scopes: Mechanical Performance Part 1 - PrecisionRifleBlog.com
Interesting that the Vortex Razor was among the worst he tested, with an error of 1.1%. It would be easy to induce a bit more error if the 100 yard measurement was not exact, since 1 yard would equal 1% of error.
If you're certain you were exactly 100 yards away and your marksmanship was spot on then the scope is probably to blame. You could send it in to be repaired or replaced, or just use a ballistic calculator that can adjust for it. Most of the good ballistic apps these days have a place to enter correction factors for elevation and windage.
Interesting that the Vortex Razor was among the worst he tested, with an error of 1.1%. It would be easy to induce a bit more error if the 100 yard measurement was not exact, since 1 yard would equal 1% of error.
If you're certain you were exactly 100 yards away and your marksmanship was spot on then the scope is probably to blame. You could send it in to be repaired or replaced, or just use a ballistic calculator that can adjust for it. Most of the good ballistic apps these days have a place to enter correction factors for elevation and windage.
El Matador has a point with adjusting the app's adjustment value to match your scope. I've had to do this with a fairly high priced (quality?) Leupold that they said was acceptable to them.
However, the adjustments need to be consistent across the range of movement (or in this case consistently off if that makes sense). I would not try to find an average and plug that into the calculator.
I do give you credit, you should be checking the adjustments. Most folks don't and just try to "true" their ballistic app to match their dope. The problem with that is that, like what may be happening with your scope, if the adjustments vary then it won't really match up and you're taking a SWAG at longer shots. If there is an animal on the receiving end of it then....?
However, the adjustments need to be consistent across the range of movement (or in this case consistently off if that makes sense). I would not try to find an average and plug that into the calculator.
I do give you credit, you should be checking the adjustments. Most folks don't and just try to "true" their ballistic app to match their dope. The problem with that is that, like what may be happening with your scope, if the adjustments vary then it won't really match up and you're taking a SWAG at longer shots. If there is an animal on the receiving end of it then....?
Ok guys, New data. Got a little extreme tonight. Measured the range again, adjusted the target and bench and started over. 100 yards,2 feet, 8.5 inches gonna call it 101
Same gun, same scope, Same ammo. Loosened the screws as suggested by Vortex, retourqued the scope to 20"lbs. Rechecked zero, minor adjustment.
First group at 3 mil = 10.6"
3mil x 101 yds x .03599 = Ex POI 10.90
10.90/10.6= 1.02 correction factor
I won't do the math here but the end results are
6 mil = 1.03 CF and 9 mil = .99 CF
Are these results acceptable? I believe with time and some reloads the group's will get better.
Thanks for all the help and suggestions. Keep'm coming !!! And I am adding a picture
Of the scope height if it will let me.
Same gun, same scope, Same ammo. Loosened the screws as suggested by Vortex, retourqued the scope to 20"lbs. Rechecked zero, minor adjustment.
First group at 3 mil = 10.6"
3mil x 101 yds x .03599 = Ex POI 10.90
10.90/10.6= 1.02 correction factor
I won't do the math here but the end results are
6 mil = 1.03 CF and 9 mil = .99 CF
Are these results acceptable? I believe with time and some reloads the group's will get better.
Thanks for all the help and suggestions. Keep'm coming !!! And I am adding a picture
Of the scope height if it will let me.
