Rifle Scopes Technical question on trajectory!

[prostreet]

Ballistics Calculator Enhanced Version

We are shooting a .300 RUM

Zero at 200 yards.

According to various ballistic calculators.

At 500 yards it calculates a bullet drop of 32.4 inches.

A custom elevation turret was ordered to all the correct specifications to a very reputable company.

Gave ALL applicable data, velocity, bullet weight, BC, etc.

Set 2 targets at 200 yards. The top one was exactly 32.4 inches above it.

Turned the turret to 500 yards, fired at the bottom target.

I was assuming the bullet would hit the top target, right on.

Not on the paper and no idea where it's hitting.

Am I making the wrong assumption, or is there a problem with the turret, or even the ballistic calculator data?

Any and all responses would be appreciated.

Thank you!

 

[Trigger Monkey]

There's not enough data here to really provide a meaningful response.

What inputs did you specifically enter in to the program? Like the bullet, velocity, BC, environmental conditions, height over bore, etc.?
Has the optic been tested on a tall test target to verify it's indeed tracking correctly?
Has the ballistic data been verified at distance?
What shooting position and support equipment did you use?
How big were those targets?
What ballistic programs did you run all of this through?

 

[wade2big]

When your turret was zeroed out, did it hit dead on at 200? These turrets dont magically sight in your rifle. You have to do that

 

[Deleted member 113831]

Ballistics Calculator Enhanced Version

We are shooting a .300 RUM

Zero at 200 yards.

According to various ballistic calculators.

At 500 yards it calculates a bullet drop of 32.4 inches.

A custom elevation turret was ordered to all the correct specifications to a very reputable company.

Gave ALL applicable data, velocity, bullet weight, BC, etc.

Set 2 targets at 200 yards. The top one was exactly 32.4 inches above it.

Turned the turret to 500 yards, fired at the bottom target.

I was assuming the bullet would hit the top target, right on.

Not on the paper and no idea where it's hitting.

Am I making the wrong assumption, or is there a problem with the turret, or even the ballistic calculator data?

Any and all responses would be appreciated.

Thank you!

Inches of drop, and the corresponding come up on the scope are not the same thing.

If the bullet is supposed to drop 32 inches from 200 to 500... then that is a 6 moa change.

Your difference in POI at 200 would be about 12 inches high.

I have no idea if your turret is correct. Not enough info for that, but your method itself is flawed.

 

[atvman400]

agree with skookum. For lack of better term you are actually loping bullets to the target. Your scope height above the bore, velocity, BC, and bullet weight all have to do with the trajectory and where the bullet will "peak" in it's arc. This is why you actually have a zero 2 places. Ar-15's usually cross at 25 and 200. 25 is when the bullet is going up and 200 is when the bullet is going down. Assume the bullet is dropping at 200 yds but can't guarantee on your set up.

 

[prostreet]

Ballistics Calculator Enhanced Version

Velocity (fps)	3127
Bullet Wt (gr)	180
Bullet BC	.588
Start Distance	0
Range Increment	50
Altitude (ft)	1000
Temperature (F)	50
Scope Ht (inch)	1.50
Zero Range (yds)	200
Wind Speed (mph)	0
Target Vely (fps)	0

 

[wade2big]

Ballistics Calculator Enhanced Version

Velocity (fps)	3127
Bullet Wt (gr)	180
Bullet BC	.588
Start Distance	0
Range Increment	50
Altitude (ft)	1000
Temperature (F)	50
Scope Ht (inch)	1.50
Zero Range (yds)	200
Wind Speed (mph)	0
Target Vely (fps)	0

You ask for help and then don’t answer the questions asked. Why?

 

[dirthead1]

Do a tall target test at 100 yards to check the accuracy of your turrets. I’m really not sure what you’re trying to do with the above test, but there are much easier and more accurate ways to test your scope tracking accuracy and drops at range.

 

[prostreet]

When your turret was zeroed out, did it hit dead on at 200? These turrets dont magically sight in your rifle. You have to do that

Exactly dead on at 200 yards. Cutting holes.

 

[wade2big]

Exactly dead on at 200 yards. Cutting holes.

I am figuring your turrets are in MOA. How many “clicks” from your 200 yard zero to your 500 yard setting? Should be roughly 24 “clicks”. (6 MOA)

Of course I don’t know which scope you have as you never said.

 

[prostreet]

I am figuring your turrets are in MOA. How many “clicks” from your 200 yard zero to your 500 yard setting? Should be roughly 24 “clicks”. (6 MOA)

Of course I don’t know which scope you have as you never said.

Vortex scope.
Custom turret should be set at "0"
It is like a bullet drop compensator.
If you range find a target at say 450 yards, all you do is turn the turret to 450. No counting clicks

Custom Turrets – Kenton Industries

kentonindustries.com

 

[wade2big]

Vortex scope.
Custom turret should be set at "0"
It is like a bullet drop compensator.
If you range find a target at say 450 yards, all you do is turn the turret to 450. No counting clicks

Custom Turrets – Kenton Industries

kentonindustries.com

I get that. Please answer my question. I am seriously trying to help you and you are making it very difficult to do so my friend.

 

[Deleted member 113831]

Vortex scope.
Custom turret should be set at "0"
It is like a bullet drop compensator.
If you range find a target at say 450 yards, all you do is turn the turret to 450. No counting clicks

Custom Turrets – Kenton Industries

kentonindustries.com

Of course there are clicks...count them. Since gravity is a constant, there is only one correct drop number. The only way to tell if the turret is fucked up is by verifying the number of clicks between the two yard lines marked on the turret.

 

[Dthomas3523]

I have rarely seen a situation where custom turrets are worth it.

 

[Deleted member 113831]

I have rarely seen a situation where custom turrets are worth it.

Meh...for a hunter that stays within 500 yards, it's probably better than holding. Changes in atmospherics won't have any consequential effect at that range.

 

[Precision Underground]

Did you measure scope height carefully?

 

[Dthomas3523]

Meh...for a hunter that stays within 500 yards, it's probably better than holding. Changes in atmospherics won't have any consequential effect at that range.

I mean as far as it being that much faster or valuable than knowing your dope and dialing.

Also, most I’ve seen were not done with all the proper info. As if someone knows the info, they also know how to dial their dope normally and don’t bother with custom turrets.

 

[eastexsteve]

Ballistics Calculator Enhanced Version

We are shooting a .300 RUM

Zero at 200 yards.

According to various ballistic calculators.

At 500 yards it calculates a bullet drop of 32.4 inches.

A custom elevation turret was ordered to all the correct specifications to a very reputable company.

Gave ALL applicable data, velocity, bullet weight, BC, etc.

Set 2 targets at 200 yards. The top one was exactly 32.4 inches above it.

Turned the turret to 500 yards, fired at the bottom target.

I was assuming the bullet would hit the top target, right on.

Not on the paper and no idea where it's hitting.

Am I making the wrong assumption, or is there a problem with the turret, or even the ballistic calculator data?

Any and all responses would be appreciated.

Thank you!

I'm going to take a stab at this and hope I can explain myself. The ballistics program is telling you that the bullet drops 32.4 inches at 500 yards, but not rising 32.4 inches high at 200 yards. There is a big difference. It's not the same arc. If it were rising 32.4 inches at 200 yards, the point of impact would not be what you would expect at 500 yards because you changed the dimensions of the arc. The easiest way to see this demonstrated is with a BB gun.

 

[DownhillFromHere]

I'm wondering if the OP is unaware of a very fundamental point: whether a scope's turrets are MOA or mils, they measure angle, not inches. A Minute Of Angle (MOA) is 1.047" @ 100 yards, 2.094" @ 200 yards, 3.141" @ 300, etc. Mils is just a different angle measurement; 1 mil is 3.6"@ 100, 7.2" @ 200, etc.

For an MOA scope with 1/4-MOA increments, one click equals 0.26" at 100 yards - but 1.3" @ 500.

So talking about inches up or down at some range is confusing at best and generally useless. You need to think in units of angle, whether MOA or mils. Mils is more accepted in the precision rifle community.

This concept applies to BDC scopes as well. Subtensions for each range will be separated from one another by some number of MOA or mils. Given that ammo that closely conforms to the subtensions at each range shares commonality with shed unicorn horns, you best know how a specific ammunition tracks against a scope's BDC marks.

While I suppose it's possible to create a custom turret as described, and Skookum is right about atmospherics not mattering much inside 500, such a scope welds one to a very specific load which was developed under very specific conditions. Seems way too limiting...

 

[FLIGHT762]

O/P, what everyone is trying to tell you is @ 200 yards, when you turn your scope turret to 500yards, your bullet strike @ 200 yards will be in the 12"- 14" above your point of aim @ 200 yards. Not 32".

You need someone who understands ballistic trajectory to give you a little education on how this works.

 

[wade2big]

Did you measure scope height carefully?

Makes little difference if he was off an inch. This along with parralax are the two most over blown non-issues.

 

[Biscuits]

Your drop at 500 yards, according to your numbers, is 32.4. That is completely different to how high above a 200 yard target your bullet will impact if you dial 500 yards on your scope.

 

[Biscuits]

Makes little difference if he was off an inch. This along with parralax are the two most over blown non-issues.

Doesn't make _that_ much of a difference...... but sorry OP, your scope centreline is almost certainly more than 1.5 inches above your bore. If you were going to order a custom turret, you should have checked this rather than used a default value.

Completely duff parallax could send you off by 3 moa ime. I have plenty of early learning curve failures where I could not figure out why bullets were landing in different locations despite the cross hairs being in the same place.

 

[wade2big]

Doesn't make _that_ much of a difference...... but sorry OP, your scope centreline is almost certainly more than 1.5 inches above your bore. If you were going to order a custom turret, you should have checked this rather than used a default value.

Completely duff parallax could send you off by 3 moa ime. I have plenty of early learning curve failures where I could not figure out why bullets were landing in different locations despite the cross hairs being in the same place.

Doesn’t matter if it is 1.75” or 2” or what he used. Makes no difference. Neither does the parralax. Parralax is only a factor at longer ranges, on high magnification, and when you can’t get on the gun correctly. Anyhow this is another argument. Neither are the problem here.

I think the OP is making stuff up for fun anyhow.

 

[Precision Underground]

Doesn’t matter if it is 1.75” or 2” or what he used. Makes no difference. Neither does the parralax. Parralax is only a factor at longer ranges, on high magnification, and when you can’t get on the gun correctly. Anyhow this is another argument. Neither are the problem here.

I think the OP is making stuff up for fun anyhow.

If he took a default value of 1.5” and his sight was a more common 2.5-2.7” that can be almost a 5” difference in impact at 500 yards. So it does matter. I don’t want to use the brain power to determine if it’s compounded by the zero height being off and it may be. But it does matter, a lot. It’s terrible advice to say don’t bother checking sight height.

 

[Deleted member 113831]

If he took a default value of 1.5” and his sight was a more common 2.5-2.7” that can be almost a 5” difference in impact at 500 yards. So it does matter. I don’t want to use the brain power to determine if it’s compounded by the zero height being off and it may be. But it does matter, a lot. It’s terrible advice to say don’t bother checking sight height.

The issue at hand isn't at 500 yards, it is at 200 yards.

Do any of you people actually read these threads before commenting?

 

[wade2big]

If he took a default value of 1.5” and his sight was a more common 2.5-2.7” that can be almost a 5” difference in impact at 500 yards. So it does matter. I don’t want to use the brain power to determine if it’s compounded by the zero height being off and it may be. But it does matter, a lot. It’s terrible advice to say don’t bother checking sight height.

Yep. The OP did say he was hitting 5” off at 500 yards. Oh wait.....he didn’t. Height over bore means nothing here especially with a 200 yard verified zero. Even your example, the error you claim is more than three times exaggerated. The further the zero the less error height over bore makes. Would’t be an inch of difference in reality. Worrying about nothing.

 

[Biscuits]

Worrying about nothing.

Well it isn't the issue, but personally I would still be cheesed if I just got my custom turret and then realised that I was almost 1.5 inches out in my scope height above bore, when I could have got it right by measuring it first.

 

[Rancid Coolaid]

Everyone is an idiot but me: 500 yard data comes from 500 yard shooting.

There is no program or device of short-cut to real-world data. Everything in this thread, some accurate in frame of reference, some not, is all built on a faulty premise.

If the OP ordered a turret based on ballistics calculator data, there is no salvaging this. Throw away the turret, put on the original, go the range and get real data, then start all over. Everyone I know that has ever bought/used a ballistic turret has eventually realized they have to track dope somewhere anyway. It is a great idea that exactly matches one very specific set of circumstances, and that set of circumstances almost never exists again in the real world. This is why log books exist with lots of important information other than a number of clicks on a turret.

Maybe that first line is a bit too harsh, I'll think on it...

 

[Deleted member 113831]

Everyone is an idiot but me: 500 yard data comes from 500 yard shooting.

There is no program or device of short-cut to real-world data. Everything in this thread, some accurate in frame of reference, some not, is all built on a faulty premise.

If the OP ordered a turret based on ballistics calculator data, there is no salvaging this. Throw away the turret, put on the original, go the range and get real data, then start all over. Everyone I know that has ever bought/used a ballistic turret has eventually realized they have to track dope somewhere anyway. It is a great idea that exactly matches one very specific set of circumstances, and that set of circumstances almost never exists again in the real world. This is why log books exist with lots of important information other than a number of clicks on a turret.

Maybe that first line is a bit too harsh, I'll think on it...

If you really shot all that data, you would realize that out to 500 yards, atmospherics don't have a consequential effect.

Even going from sea level to 10,000ft doesn't change things all that much.

So yeah...BDC's in general are viable within that range. I don't want to be the one to have to defend their use, but the fact that they can get the job done out to 500 is plainly evident.

 

[Rancid Coolaid]

Again, super slow this time: conversations of 500 yard data cannot be founded on 200 yard shots. We can go into turrets and atmospherics and what impact zeroing at 70 degrees has when taking a shot at 20 degrees - but none of that matters. Unless I missed it, we are discussing a 500 yard shot in terms of 200 yard shots. It's kinda like saying you really good at fucking because you are really good at jacking off.

Anything at range based on a ballistics calculator is terrible, terrible planning and executing.

I reread the original post to be sure I didn't miss it, and yup, no mention of measuring anything: no chrono, no 500 yard data, nada. Maybe it happened but was excluded from the post, don't know, can't help solve a problem with zero real-world data. Hell, even the 200 yard shot with expectations of a 32 inch drop (though off) doesn't have a data point.

I'll leave this now, given that I cannot help. I usually try to help.

Usually.

 

[Deleted member 113831]

Again, super slow this time: conversations of 500 yard data cannot be founded on 200 yard shots. We can go into turrets and atmospherics and what impact zeroing at 70 degrees has when taking a shot at 20 degrees - but none of that matters. Unless I missed it, we are discussing a 500 yard shot in terms of 200 yard shots. It's kinda like saying you really good at fucking because you are really good at jacking off.

Anything at range based on a ballistics calculator is terrible, terrible planning and executing.

I reread the original post to be sure I didn't miss it, and yup, no mention of measuring anything: no chrono, no 500 yard data, nada. Maybe it happened but was excluded from the post, don't know, can't help solve a problem with zero real-world data. Hell, even the 200 yard shot with expectations of a 32 inch drop (though off) doesn't have a data point.

I'll leave this now, given that I cannot help. I usually try to help.

Usually.

I guess I kinda missed where you were going with that. Sorry brother. Mea Culpa.

 

[prostreet]

Thank you all for the comments!

 

[wade2big]

Again, super slow this time: conversations of 500 yard data cannot be founded on 200 yard shots. We can go into turrets and atmospherics and what impact zeroing at 70 degrees has when taking a shot at 20 degrees - but none of that matters. Unless I missed it, we are discussing a 500 yard shot in terms of 200 yard shots. It's kinda like saying you really good at fucking because you are really good at jacking off.

Anything at range based on a ballistics calculator is terrible, terrible planning and executing.

I reread the original post to be sure I didn't miss it, and yup, no mention of measuring anything: no chrono, no 500 yard data, nada. Maybe it happened but was excluded from the post, don't know, can't help solve a problem with zero real-world data. Hell, even the 200 yard shot with expectations of a 32 inch drop (though off) doesn't have a data point.

I'll leave this now, given that I cannot help. I usually try to help.

Usually.

Almost no information was shared by the OP. I think he is playing games or just not very smart. He chimed in a bit ago and thanked us for the comments that were based on wild ass guesses because he cant answer questions or provide information. Poor guy. Entertaining thread anyhow.

i get where you were going with your post and you are correct for the most part. A general idea can be obtained at 200. Good data cannot.

 

[Rancid Coolaid]

Sorry, it’s Friday, it did come out a little asshole-ish, wasn’t meant to. The point is you know nothing about 500 till you shoot 500. Extrapolating can get you in the ballpark, but just that.

 

[RayDBonz]

As mentioned above, the bullet drop at 500 yards has nothing to do with where the bullet is at 200 yards. Trajectory is a parabola. So yes, your assumption is wrong.

The better question should be - where did it hit on the 500 yard target? That will tell you if the custom turrets are correct.

 

[Hesperidins]

@prostreet, when populating the order form in their site did you include the Field Data section? Provide that data to us.

Thanks.

 

[Precision Underground]

Yep. The OP did say he was hitting 5” off at 500 yards. Oh wait.....he didn’t. Height over bore means nothing here especially with a 200 yard verified zero. Even your example, the error you claim is more than three times exaggerated. The further the zero the less error height over bore makes. Would’t be an inch of difference in reality. Worrying about nothing.

Your tag line is dead on.

 

[wade2big]

Your tag line is dead on.

If the OP was off on his height over bore by 1” with a 200 yard zero, there is less than 4” difference at 1,000 yards (less than .5 moa). Worry about stuff that matters. This is a hunting setup at 500 yards. Height over bore means dick. Should he measure and get it right. Yes. Does it matter NO.

 

[koshkin]

Learn to think about trajectory in angular units: MOA or mrad. Thinking about drop in inches is just a bad idea.

ILya

 

[Precision Underground]

If the OP was off on his height over bore by 1” with a 200 yard zero, there is less than 4” difference at 1,000 yards (less than .5 moa). Worry about stuff that matters. This is a hunting setup at 500 yards. Height over bore means dick. Should he measure and get it right. Yes. Does it matter NO.

You’re right. When you take the time to order custom turrets you should not worry about getting all the data inputs right. Just go with whatever the calculator defaults to. It’s fine. You know a lot.

 

[wade2big]

You’re right. When you take the time to order custom turrets you should not worry about getting all the data inputs right. Just go with whatever the calculator defaults to. It’s fine. You know a lot.

You are arguing crap that doesn’t even pertain to the OP’s fake thread he started. You cant comprehend what you read either it seems. I never said what you seem to think I did. In fact you almost repeated what I said in the thread you quoted. Think a bit and stop focusing on what doesnt matter. It’s a habit of yours it seems.

edit: cuss me back and let’s call it even and move on.