By popular request ...my newb questions in 1 post (4dof, cant, angles, barrel life)

[TheLimey]

Hello, I've been building up a few questions about dope, 4dof etc. Hope it's ok if I just spew them here...

On 4DOF, when I add a 5mph tailwind, elevation is 0.1 mil higher. When I add a headwind, the elevation comes back 0.1 lower. I thought it would be the other way around. If the tailwind is reducing drag/pushing the bullet faster why do I have to come up more? Same kind of question for headwind. Doesn’t gravity have more time to push bullet down? Leading to higher, not lower elevation?

At what distance does the angle of fire become a critical component into the 4DOF? For matches so far I’ve put in a rough angle for all shots in the match. The dope come back different when I try different angles so I'm assuming I should factor in. Should I prepare for matches by separating "flat" from "top of hill" type shots ...would that be enough?

At what distance does cant really become an issue? Are you checking can’t with bubble level before each shot? Whenever I’m off the bench and getting in a new position I’m ALWAYS canted and need to adjust. Is everybody checking all the time? Another reason to practice both eyes open?

How far can I push barrel life of 6.5 Creedmoor? Can I push it to 3000 without any real problems? If my zero groups at 100 get a bit bigger, that might be ok. Can I do any other kind of damage to the rifle by shooting it passed recommended shots (read that 2000 is about the number)?

When I need a new barrel do I simply order a new barrel from Tikka and get it fitted? Should I get another manufacturers barrel (Tikka Tac A1)?

Cheers!

 

[Dthomas3523]

1: headwind will cause bullet to hit lower, tail wind will cause it to hit higher. At practical distances and speeds we shoot, it’s negligible and inside the error of the shooter/system. Not to mention it’s rare the stars align for it to be a perfect head or tail wind and the terrain to allow for it as well. Don’t worry with things that mess with .1mil at 1k. You’ll rack your brain over shit that doesn’t matter.

2: Angle has to be pretty steep to matter. For example, 10deg is about .2 at 1k. Again, don’t worry with it unless you’re at a fairly significant angle.

3: technically cant is an issue at all ranges. But it’s dependent on the target size and conditions. If you’re always canted, either your rifle is not set up correctly for you, you have fundamental position errors, or something is fucked up with your equilibrium. Get a level (I prefer the send it electronic over a cheap bubble) and use it to train with. The less things you need to look at on the clock, the better. So train with it so you don’t need to rely on it more than just to glance at after building a position.

4: if you’re ok adding powder (or ok with decreasing velocity) you can take a 6.5cm fairly far if you are basing your barrel life on accuracy. Serious competitors using scrap a barrel for match use when it shows the first velocity drop, or gets close to the round count where they usually see the drop. Especially if you are shouldering the expense of a 2 day match. You don’t want a barrel to cost you. And all barrel are different. The hotter you run, the more inconsistent barrel life is from barrel to barrel. So, this is a personal decision. I’ve seen guys take 6.5 to well over 3k and seen others pull them at 2k.

5: I’d personally get a smith to spin up a barrel. But that’s up to you.

 

[vinniedelpino]

Hello, I've been building up a few questions about dope, 4dof etc. Hope it's ok if I just spew them here...

On 4DOF, when I add a 5mph tailwind, elevation is 0.1 mil higher. When I add a headwind, the elevation comes back 0.1 lower. I thought it would be the other way around. If the tailwind is reducing drag/pushing the bullet faster why do I have to come up more? Same kind of question for headwind. Doesn’t gravity have more time to push bullet down? Leading to higher, not lower elevation?

At what distance does the angle of fire become a critical component into the 4DOF? For matches so far I’ve put in a rough angle for all shots in the match. The dope come back different when I try different angles so I'm assuming I should factor in. Should I prepare for matches by separating "flat" from "top of hill" type shots ...would that be enough?

At what distance does cant really become an issue? Are you checking can’t with bubble level before each shot? Whenever I’m off the bench and getting in a new position I’m ALWAYS canted and need to adjust. Is everybody checking all the time? Another reason to practice both eyes open?

How far can I push barrel life of 6.5 Creedmoor? Can I push it to 3000 without any real problems? If my zero groups at 100 get a bit bigger, that might be ok. Can I do any other kind of damage to the rifle by shooting it passed recommended shots (read that 2000 is about the number)?

When I need a new barrel do I simply order a new barrel from Tikka and get it fitted? Should I get another manufacturers barrel (Tikka Tac A1)?

Cheers!

I wouldn't order a barrel from Tikka. There are a million different lengths, contours and options available through the aftermarket. If you have the money, get a top quality blank and have it spun up by a good smith. Otherwise, I'd get a quality aftermarket prefit and keep shooting. Out of the box tikka barrels are good for stock barrels. Damn good. But there are dozens of aftermarket barrel makers that will probably get you a little more velocity, accuracy and consistency for a comparable price with the ability to customize it however you'd like.

 

[TheLimey]

I wouldn't order a barrel from Tikka. There are a million different lengths, contours and options available through the aftermarket. If you have the money, get a top quality blank and have it spun up by a good smith. Otherwise, I'd get a quality aftermarket prefit and keep shooting. Out of the box tikka barrels are good for stock barrels. Damn good. But there are dozens of aftermarket barrel makers that will probably get you a little more velocity, accuracy and consistency for a comparable price with the ability to customize it however you'd like.

Thanks man. I'll need a 1:8 twist 24 inch barrel but beyond that not sure what else to ask for. I guessed a few specs over at kreiger barrel (only company I could think of) ..Heavy Target barrel was about 400 bucks. Just learned about 5R rifling. Any reason not to have that?

 

[TheLimey]

1: headwind will cause bullet to hit lower, tail wind will cause it to hit higher. At practical distances and speeds we shoot, it’s negligible and inside the error of the shooter/system. Not to mention it’s rare the stars align for it to be a perfect head or tail wind and the terrain to allow for it as well. Don’t worry with things that mess with .1mil at 1k. You’ll rack your brain over shit that doesn’t matter.

2: Angle has to be pretty steep to matter. For example, 10deg is about .2 at 1k. Again, don’t worry with it unless you’re at a fairly significant angle.

3: technically cant is an issue at all ranges. But it’s dependent on the target size and conditions. If you’re always canted, either your rifle is not set up correctly for you, you have fundamental position errors, or something is fucked up with your equilibrium. Get a level (I prefer the send it electronic over a cheap bubble) and use it to train with. The less things you need to look at on the clock, the better. So train with it so you don’t need to rely on it more than just to glance at after building a position.

4: if you’re ok adding powder (or ok with decreasing velocity) you can take a 6.5cm fairly far if you are basing your barrel life on accuracy. Serious competitors using scrap a barrel for match use when it shows the first velocity drop, or gets close to the round count where they usually see the drop. Especially if you are shouldering the expense of a 2 day match. You don’t want a barrel to cost you. And all barrel are different. The hotter you run, the more inconsistent barrel life is from barrel to barrel. So, this is a personal decision. I’ve seen guys take 6.5 to well over 3k and seen others pull them at 2k.

5: I’d personally get a smith to spin up a barrel. But that’s up to you.

Cheers! I'm trying to turn over stones to be sure(r) that when I miss it's my fault.

I don't reload or have a chronograph (yet) to tweak or check velocity. I'll start researching barrel stuff. I think I have at least 2000 rounds thru my current barrel. Would the velocity drop in an overshot barrel be enough to change my dope enough to make me miss?

I have a cheapo bubble level for the cant stuff... that send it one looks faaancy.

 

[AllenOne1]

When you are plugging in headwind or tail wind you are putting these in as tailwind is 6 o clock and headwind is 12 o clock right? Because the answers you got originally are backward. Tailwind take elevation out and headwind put elevation in because the bullet is slowing down.

 

[Jack Master]

Dthomas3523 is spot on with his answers.

Here is the math on a canted rifle

So after reading 400(ish) posts about scope mounting and leveling I had to do the math.

Every time a scope mounting or leveling thread is posted it usually leads to conversations about weather the rifle needs to be level when the scope is mounted level. And sometimes is goes into weather the scope needs to be mounted directly over the bore and not offset from the bore. Well, math 'never' lies. So... attached is a sheet I put together for the down range effects of...1) mounting your scope with an offset from the bore, 2) mounting the scope level with the rifle not level, and 3) effects of a canted reticle dues to not being mounted correctly or canting the entire system.

I was very surprised to find the offsets due to mounting or rifle cant (with level scope) are very minimal. especially when compared to the canting of the scope. I could understand needing to worry much more about the offsets when shooting over... maybe 3000 yards, but even then its a strech then compaired to wind calls or actual scope cant.

Conclusions:
We need to have a level reticle or level tracking (not always the same) but don't fret over the mounting offsets (case 1) or canting the rifle with a level scope (case 2). Do worry about canting the scope.

View attachment 7074705

 

[Jack Master]

Here is how I handel angle shooting to know when it matters

So after listening to @Cjwise5 podcast about his experience with high angle shooting, I decided to crunch a few numbers. (I like numbers)

Question: When Do I need to worry about making an Angle Correction?

First of all, we need to understand the amount of elevation change needed to create shooting angles. As Joel said, shooting a 400yd target from the top of 2 conex boxes does not even start to have the heights needed to make angle corrections. Here is a chart the shows how many feet of elevation we need to be above or below our target to create an angle situation. You will see at 400 yards you need to be up 208 feet to get a 10 degree angle.

View attachment 7310896 View attachment 7311009

But what if we do have an angle situation. How much does it effect our come-ups at angles and distances? Here is a chart for my 6.5 Creed and the corrections needed for angle shooting. This is presented in 2 ways. The first is the actual come-up and the second is the difference in come-up from our flat trajectory. I have deleted any come-ups that are less then 0.07 mil change. Studying the 2nd chart can show us the relativity of the come-up change and when we need to be aware of the conditions to make adjustments. I can start to eliminate areas of concern: any target inside 150 yards is less than 0.2Mil or .75-ish MOA of change, that is less than 1"; any target less than 20 degrees out to 300 yards

View attachment 7312122

For me, this is one of things we need to ask, does it really matter? How much will this really effect my bullet trajectory? For most shooters this will likely never be an issue. If we are mountain shooting, yes, this will matter. Most shooting ranges are on relatively flat land. I live in Iowa and I doubt I can find a range in the state that I'll need to account for high angles even if they have obstacles that add elevation. Even if I did find a steep range it might have an effect on my bullet but not likely more than 1MOA. To prove this, Lets analyse the dope charts with the elevation gain chart. I'll delete the elevation changes that will effect my bullet by less then 0.2mil or 3/4moa on the Come-up sheet. This will identify the conditions I need to look for before I even start to think about making an angle correction.

View attachment 7312123

This chart identify's the change in height I need to have before I start to worry about angle changes. I did not notice, until I did this exercise, that at each angle the height is right at 330 feet (or more) of elevation change. Now I know what to look for when asking myself "will this angle matter?". I can now ask, "Is it 300 feet of change?"... 24 feet of Conex box... not gonna matter.

Answer: When shooting upward or downward more than 300 Feet in Elevation for my Rifle.

 

[TheLimey]

When you are plugging in headwind or tail wind you are putting these in as tailwind is 6 o clock and headwind is 12 o clock right? Because the answers you got originally are backward. Tailwind take elevation out and headwind put elevation in because the bullet is slowing down.

Hmmm I'm wondering ...is it the angle I added? When I put the angle to zero the come up differences were negligible.

But here's what I see with the angle.

5 mph tailwind come up: 2.9
5 mph headwind come up: 2.6
No wind come up: 2.7

 

[AllenOne1]

Hmmm I'm wondering ...is it the angle I added? When I put the angle to zero the come up differences were negligible.

But here's what I see with the angle.

5 mph tailwind come up: 2.9
5 mph headwind come up: 2.6
No wind come up: 2.7

Tailwind being 180 degrees?
Headwind being 0 degrees?

Those results are completely backwards. The shooting angle would be zero unless you are shooting up or down hill that may be your issue, I would try it at zero and see what you get.

 

[Lowlight]

Headwinds and Tailwinds, especially 5MPH don't do shit, ignore that nonsense,

We shoot in high winds monthly and have shot in a 45 MPH Headwind that only had a 5 MPH crosswind component, we hit spot on... no change in dope to hit our truing bars.

We shot this weekend in 35 MPH winds that were doped to 25 MPH consistently, no issue with elevation it was spot on and consistent after being doped at 6 MPH two days before,

Much of this software stuff is WRONG, go out and shoot and you will learn this quickly, they are good at some things not so good at others.



We shoot in this wind out to 675 yards, we had many first-round hits at all distances under these same conditions

 

[Lowlight]

The trick to a Headwind or Tailwind is not elevation, it's windage,

The thing with these winds is, you never get a strictly 0-degree wind, it changes directions constantly so you have to manage the left and right that happens instantly,

this was doing a 45 MPH headwind while teaching a class, we did not stop shooting, so our experience is not theoretical but proven,

 

[TheLimey]

Tailwind being 180 degrees?
Headwind being 0 degrees?

Those results are completely backwards. The shooting angle would be zero unless you are shooting up or down hill that may be your issue, I would try it at zero and see what you get.

Yeah they had me scratching my head too. The difference IS negligible when no angle input though.

 

[TheLimey]

Headwinds and Tailwinds, especially 5MPH don't do shit, ignore that nonsense,

We shoot in high winds monthly and have shot in a 45 MPH Headwind that only had a 5 MPH crosswind component, we hit spot on... no change in dope to hit our truing bars.

We shot this weekend in 35 MPH winds that were doped to 25 MPH consistently, no issue with elevation it was spot on and consistent after being doped at 6 MPH two days before,

Much of this software stuff is WRONG, go out and shoot and you will learn this quickly, they are good at some things not so good at others.



We shoot in this wind out to 675 yards, we had many first-round hits at all distances under these same conditions

Cheers... yeah I'm figuring it out as I go along. Sad to hear I can't trust the software..I've been leaning on it. I have to figure out a way to get pure dope for my (factory) ammo and rifle.

 

[Lowlight]

Shooting is the best method for determining your dope,

you shoot first, then true the software to your real world results,

The software is a prediction, based on information that it cannot manage as advertised so they have to add in flourishes to fill in the gaps.

When you shoot first and align the software to the results you have better results with software. But software is not the end all, it's limited by the information, the formulas, the processing power of the phone, etc.

There is a reason we true, because of software limitations. We true because of shooter influence, we true because there are holes in the software's ability to predict an outcome without a frame of reference.

 

[Jack Master]

Here is a diagram of what the program is doing. This is 100% due to the inclined or declined shooting angle. Problem is, the program keeps the wind horizontal. I drew this as if there is a mountainside you are shooting up or down. Imagine this across a canyon without the ground and these winds will be present.

Don't use the inclined decline with a head or tail wand and you'll be fine.

 

[TheLimey]

Shooting is the best method for determining your dope,

you shoot first, then true the software to your real world results,

The software is a prediction, based on information that it cannot manage as advertised so they have to add in flourishes to fill in the gaps.

When you shoot first and align the software to the results you have better results with software. But software is not the end all, it's limited by the information, the formulas, the processing power of the phone, etc.

There is a reason we true, because of software limitations. We true because of shooter influence, we true because there are holes in the software's ability to predict an outcome without a frame of reference.

Copy that. Should I break out the tall target test again at 100yds? I kind of goofed around with that when I first got my rifle but I never used any info. tbh I only did it cos I saw a video on it but now maybe I can actually use it.

 

[TheLimey]

Here is a diagram of what the program is doing. This is 100% due to the inclined or declined shooting angle. Problem is, the program keeps the wind horizontal. I drew this as if there is a mountainside you are shooting up or down. Imagine this across a canyon without the ground and these winds will be present.

View attachment 7445909

Don't use the inclined decline with a head or tail wand and you'll be fine.

Superb. Love that. Makes sense. I appreciate you sharing that.