Be gentle with me...

[Lawless]

I use Strelok Pro and it has been just about spot on every time.

Is there a way in the software to calculate and record what to dial to when switching from 55g 5.56 to 77g OTM in the same rifle at a specified distance?

Let’s say I dial X mils at 500 yards with 55g and switch to 77g, can the software calculate the difference somehow or do I just look at the tables and manually do the math?

 

[PinesAndProjectiles]

You can build different profiles for different bullets, but for the same rifle/scope setup.

Once you enter in the data for each, it's as simple as choosing a different bullet profile and opening the table.

 

[Deleted member 113831]

I use Strelok Pro and it has been just about spot on every time.

Is there a way in the software to calculate and record what to dial to when switching from 55g 5.56 to 77g OTM in the same rifle at a specified distance?

Let’s say I dial X mils at 500 yards with 55g and switch to 77g, can the software calculate the difference somehow or do I just look at the tables and manually do the math?

What MM said^^^ but with the added caveat that you need to input your known zero offset into any bullet profile other than your primary load.

 

[PinesAndProjectiles]

Yep, forgot about that part. But Strelok allows for an offset which makes is easy.

 

[TomH Tx]

I have several different bullet profiles set up in Strelok under my .308AR10, and my RPR6.5. It allows you to "change cartridge" very easily between saved cartridge profiles.

 

[Lawless]

Yeah I have the different loads set up but with different loads, the zero will be different in the scope even at the same distance.

Is there any way to calculate the difference in the software based on the load data?

To do it manually, I would need to zero the 55g load, zero the turrets, then go out and shoot 77g to zero. Then subtract the difference in mils.

What I would like is to just have the software predict the approximate difference at a specific distance.

Like I’m shooting 55g and pop in a mag of 77g and via software just knew the difference in mils to correct.

 

[Lawless]

Thinking more about it, I guess once I knew the difference in mils of a known zero distance between the loads, I could manually create a chart by plotting the difference plus the zero correction between loads.

 

[TomH Tx]

Upon giving your question further thought, it really is a VERY good question, and I did not fully understand it initially. I have created "dope" sheets for multiple different rounds, temperatures, distances, etc....., but even if you actually ZERO for each, if you are in the field, having zero'd for say a 6.5 140gr, and then switch to a 125gr or 147gr, the gun may not be properly set up to use what Strelok calls for. Seems like you would have to zero for each round, at consistent temperature, and note the differences in whatever adjustments you had to make from whatever round you set as your "baseline. As if this is not complicated enough already.

 

[Lawless]

Upon giving your question further thought, it really is a VERY good question, and I did not fully understand it initially. I have created "dope" sheets for multiple different rounds, temperatures, distances, etc....., but even if you actually ZERO for each, if you are in the field, having zero'd for say a 6.5 140gr, and then switch to a 125gr or 147gr, the gun may not be properly set up to use what Strelok calls for. Seems like you would have to zero for each round, at consistent temperature, and note the differences in whatever adjustments you had to make from whatever round you set as your "baseline. As if this is not complicated enough already.

Yep, you understand what I was asking.

Even if you have an accurate dope chart, it is all based off of a known zero, and that zero will be optically different between loads. Especially as big a difference as between M193 and 77otm in 5.56.

So, I guess perhaps as Frank was eluding to in his trailer for the class on zero offset you can somewhat use the software. Unless I misunderstand how the offset works though, it can’t calculate what will be happening 200 yards farther with a different bullet with different weight,velocity and BC.

I wish there was simply a “switch to different load” easy button in Strelok

 

[davsco]

So, I guess perhaps as Frank was eluding to in his trailer for the class on zero offset you can somewhat use the software. Unless I misunderstand how the offset works though, it can’t calculate what will be happening 200 yards farther with a different bullet with different weight,velocity and BC.

as noted above, zero your rifle with your one load at 100 (or whatever distance you zero at). then shoot your 2nd load and see how far off you are at that same distance. that's your offset. enter both loads in your ballistic calculator and you're good to go. to test, call up your 2nd load in your calc and it should say you will be x high or low at your zero distance, matching what you saw. then your calc will show you what you need at various yardages for both loads.

i will say though the best thing is to actually shoot both loads at your various distances to see what is actually happening. if your bc, scope height, velocity, etc is off a little, can have big diffs downrange.

 

[Lawless]

It will give you the offset at that distance but the flight being different arcs between very different bullets, it would not be correct at say 300 yards farther (or am I missing something?)

When I pull up a different load, even if they both have a 100 yard zero, that zero requires different settings in the optic.

I guess like I was saying earlier I would have to get the difference in mils between the two load’s zeros, then use the charts and add in that difference to switch loads and dial the correct (approximate) change at a given distance.

Or simply shoot each at each distance and record the difference but my question is whether any software could predict it.

 

[Racer88]

Strelok Pro user here. I think I've got a pretty good handle on it.... been using it for a year or two.

The solution to this is very easy. You'll zero the rifle with only ONE ammo. Perhaps your favorite load, for example. That's your zero for Strelok. That's your baseline. Everything else is built from there.

Then... shoot the 2nd load WITHOUT changing the the turret on your rifle (from the original zero with your favorite load). Where does the 2nd ammo group? Let's say 1 inch low and 1 inch right from the POA. That's your OFFSET. Enter the offset values for that cartridge in Strelok. Rinse and repeat.

So, now... whenever you shoot Cartridge B, Strelok will automatically compensate the output based on the offsets from zero. Hopefully that made sense. It's worked great for me, and it's easy.

Here's a link to Strelok's page on how to use offsets.

http://www.borisov.mobi/strelokpro/android/cartridges.htm
(Scroll down the article. The first example is how to set up an offset for cold bore. He later shows examples of different cartridges.)

 

[TomH Tx]

I think this makes sense. You essentially "zero" the initial round. Then you "zero" the second by measuring and entering the offset from the first, and saving that as a different projectile file. So if you change rounds out in the field, you switch projectiles in Strelok, and IT does the math for you. Pretty cool really. In his teaser vid, Frank (Lowlight) was saying that you could do the same for a round suppressed, and unsuppressed, using the offset. I am going to have to start "clean sheet" next weekend and try this. VERY interesting thread.

 

[Racer88]

I think this makes sense. You essentially "zero" the initial round. Then you "zero" the second by measuring and entering the offset from the first, and saving that as a different projectile file. So if you change rounds out in the field, you switch projectiles in Strelok, and IT does the math for you. Pretty cool really. In his teaser vid, Frank (Lowlight) was saying that you could do the same for a round suppressed, and unsuppressed, using the offset. I am going to have to start "clean sheet" next weekend and try this. VERY interesting thread.

Yep. You got it.

 

[DownhillFromHere]

Here's the easy way to visualize it... Say you've zeroed at 100 yards with ammo "A." Then you try ammo "B" and find it prints 1.5 MOA / 0.4 mil low and 0.5 MOA / 0.1mil left. Don't mess with your zero on the scope!

In your new "B" cartridge profile, you enter -1.5 MOA and -0.5 in the vertical and horizontal offset fields respectively (or -.4 and -.1 mil - you can choose MOA or mil). Save the change.

Now click Done to return to the main screen. Enter 100 yards for distance and tap Calculate. You will see U1.5 MOA / U0.4 mrad and R0.5 MOA / R0.1 respectively for Vert. and Hor. values. Magic. And you can true the value at longer ranges as well.

Now switch back to ammo "A" in Strelok, which is your baseline zero. Hit calculate for 100 yards, and your vertical and horizontal values are, surprise, 0 and 0. Magic.

It really is a well-done app.

 

[Lawless]

This still is not what I am asking. I understand the offset and truing at a certain distance, but that will not be the same offset at 100 yards that it will be at 500 yards, it isn’t linear between two different weight and BCs. The flight of a 55g .223 and a 77g will have totally different arcs.

Or, am I misunderstanding the Strelok instructions, and once the offset is entered for the different cartridge, it does the math out to whatever distance?

 

[PinesAndProjectiles]

This still is not what I am asking. I understand the offset and truing at a certain distance, but that will not be the same offset at 100 yards that it will be at 500 yards, it isn’t linear between two different weight and BCs. The flight of a 55g .223 and a 77g will have totally different arcs.

Or, am I misunderstanding the Strelok instructions, and once the offset is entered for the different cartridge, it does the math out to whatever distance?

Once you enter the information with Ammo A into Strelok with a zero distance, and Ammo B with an offset, the necessary changes will be automatically calculated every time you use the Ammo B within the program.

If Ammo B shoots 0 mil low and .4 mil left, then that is entered into your offset.

When calculating ranges for Ammo B, your numbers will always be .4 mils right to compensate for the offset.

Your elevation will be different because of velocity, BC, etc.

 

[Deleted member 113831]

This still is not what I am asking. I understand the offset and truing at a certain distance, but that will not be the same offset at 100 yards that it will be at 500 yards, it isn’t linear between two different weight and BCs. The flight of a 55g .223 and a 77g will have totally different arcs.

Or, am I misunderstanding the Strelok instructions, and once the offset is entered for the different cartridge, it does the math out to whatever distance?

The trajectories of the 2 rounds are of course different, as is the wind drift. You put in all the pertinent info for each bullet. The computer calculates the trajectory the same as if you had zero'd at 100 yards (or whatever zero you tell it). The only difference is the starting point. If you put in the offset then the computer accounts for that offset.

Think of it like this...if you move your scope 1 moa left, that moves your ENTIRE TRAJECTORY 1 moa left, not just your 100 yard point of impact. You are telling the computer that THE ENTIRE TRAJECTORY of bullet "A" has been offset from bullet "B". The computer gives the adjustments needed to compensate.

 

[Lawless]

Once you enter the information with Ammo A into Strelok with a zero distance, and Ammo B with an offset, the necessary changes will be automatically calculated every time you use the Ammo B within the program.

If Ammo B shoots 0 mil low and .4 mil left, then that is entered into your offset.

When calculating ranges for Ammo B, your numbers will always be .4 mils right to compensate for the offset.

Your elevation will be different because of velocity, BC, etc.

The trajectories of the 2 rounds are of course different, as is the wind drift. You put in all the pertinent info for each bullet. The computer calculates the trajectory the same as if you had zero'd at 100 yards (or whatever zero you tell it). The only difference is the starting point. If you put in the offset then the computer accounts for that offset.

Think of it like this...if you move your scope 1 moa left, that moves your ENTIRE TRAJECTORY 1 moa left, not just your 100 yard point of impact. You are telling the computer that THE ENTIRE TRAJECTORY of bullet "A" has been offset from bullet "B". The computer gives the adjustments needed to compensate.

Thanks gentlemen, after reading all of this again and the Strelok instructions again, I get it.

So allow me to talk it out to be sure.

Each different cartridge entered, whether the same cartridge through a can or a completely different bullet, can use the zero offset to show what to dial to without actually rezeroing the optic.

To do this, I shoot the new cartridge at the same zero distance as the main/go to load and measure the average difference and then input it into the zero offset under the new cartridge’s data.

This then gives the correct adjustments or hold offs for the new cartridge based on how the scope is set for the original cartridge.

Ex. I shoot M193 as my usual load and it is zeroed at 47 yards. I then shoot Black Hills 77OTM at 47 yards and it is 1.25” low. I enter -1.25 as my offset and now every distance I enter, as well as the table, will show in mils what the adjustments are based on my M193 zero set in the optic.

I think I was confusing “truing” with this zero offset function.

 

[Lawless]

Now about truing BC and velocity, once I do this it changes all adjustments at all distances for that cartridge based on the measured BC and Velocity it extrapolates from my real world results?

Do I do BC or velocity first? Or does it matter?

 

[Deleted member 113831]

Now about truing BC and velocity, once I do this it changes all adjustments at all distances for that cartridge based on the measured BC and Velocity it extrapolates from my real world results?

Do I do BC or velocity first? Or does it matter?

In the same way it changes the trajectory it also changes it's relationship to the reference load. But as long as the zero offset is the same, then all offsets down range will be accounted for.

Some adjust BC to match 800 yard trajectory first, and tweak velocity up or down slightly ( less than 1%) after.

I choose to tweak velocity to match at 500 ( should still should be no more than 1%) and tweak BC after. It makes more sense to me to do it that way, but that's just me.

 

[PinesAndProjectiles]

Now about truing BC and velocity, once I do this it changes all adjustments at all distances for that cartridge based on the measured BC and Velocity it extrapolates from my real world results?

Do I do BC or velocity first? Or does it matter?

Brian Litz says that inside the transonic zone to true the velocity and past the transonic to true the BC.

I only true velocity as im not shooting too much farther than transonic.

There are probably a lot of opinions on this.

 

[Lawless]

Thank you gentlemen. You have all helped me tremendously.

 

[alcap]

There is Strelok user group on FB a d Boris is. Pretty active on it.

 

[TomH Tx]

UPDATE: I truly found this thread very interesting. So today I took my RPR 6.5 out to my Ranch, slogged out 100 yards in the saturated mush, and planted a target. I verified my zero using my suppressor, and changed the name of my rifle in Strelok to include the word SUPPR. I then removed the suppressor, used the same target, made NO other adjustments whatsoever to my scope, and aimed for the same spot. When I retrieved the target, my impacts averaged 1.25" HIGHER than when suppressed. SO, using the info from this thread, I created a "NEW RIFLE" in Strelok, and my other apps, and called it NOT SUPPR. Under the NOT SUPPR rifle, I made vertical offset entry of 1.25", and saved the new rifle. Then, using Strelok, and plugging in 500 yds, my SUPPR called for 2.9mils, but switching to my NOT SUPPR, the call was for only 2.6 mils, which certainly seems consistent with the RPR shooting HIGHER when NOT suppressed. Anyway, I just wanted to pass along this field verification of sorts. I may be easily amused, but this seems pretty cool! Now I just need to make sure I am choosing the correct rifle, although I normally do shoot suppressed, so that will be my default setting.

 

[Racer88]

UPDATE: I truly found this thread very interesting. So today I took my RPR 6.5 out to my Ranch, slogged out 100 yards in the saturated mush, and planted a target. I verified my zero using my suppressor, and changed the name of my rifle in Strelok to include the word SUPPR. I then removed the suppressor, used the same target, made NO other adjustments whatsoever to my scope, and aimed for the same spot. When I retrieved the target, my impacts averaged 1.25" HIGHER than when suppressed. SO, using the info from this thread, I created a "NEW RIFLE" in Strelok, and my other apps, and called it NOT SUPPR. Under the NOT SUPPR rifle, I made vertical offset entry of 1.25", and saved the new rifle. Then, using Strelok, and plugging in 500 yds, my SUPPR called for 2.9mils, but switching to my NOT SUPPR, the call was for only 2.6 mils, which certainly seems consistent with the RPR shooting HIGHER when NOT suppressed. Anyway, I just wanted to pass along this field verification of sorts. I may be easily amused, but this seems pretty cool! Now I just need to make sure I am choosing the correct rifle, although I normally do shoot suppressed, so that will be my default setting.

If you're creating a separate RIFLE, then there's no need for the offset function (assuming the same ammo cartridge). You can just create a zero for the separate rifle. The purpose of the offset is to effectively create multiple zeroes for the same rifle.... One actual zero, and the other cartridges with their respective offsets to that primary zero. Likewise, you can create offsets (for each cartridge) when the suppressor is on.

But, nothing wrong with creating a separate rifle w/ suppressor. It's another way to do it. You can create a primary zero for it and then offsets for various ammo cartridges on the suppressed rifle.

Hope that made sense.

 

[TomH Tx]

If you're creating a separate RIFLE, then there's no need for the offset function (assuming the same ammo cartridge). You can just create a zero for the separate rifle. The purpose of the offset is to effectively create multiple zeroes for the same rifle.... One actual zero, and the other cartridges with their respective offsets to that primary zero. Likewise, you can create offsets (for each cartridge) when the suppressor is on.

But, nothing wrong with creating a separate rifle w/ suppressor. It's another way to do it. You can create a primary zero for it and then offsets for various ammo cartridges on the suppressed rifle.

Hope that made sense.

I appreciate the response, but I am going to need to think this through further. I guess I am not getting it.
Per the OP's original question, the purpose of the exercise was to be able to switch ammo "on the fly" while in the field.
I just wanted to run suppressed, or not, using the same exact ammo.
To me, if I did not save the Unsuppressed as a new rifle, I would have to manually rotate turrets to get to the "other" zero if I removed the suppressor while in the field.
What I was trying to accomplish was created an entire "line" where if I was shooting suppressed, and chose that rifle, with the SAME ammo as was zero'd with, Strelok (or whatever) would calculate my settings at various ranges. If I switched to unsuppressed, likewise so long as same ammo. I do think that I would have to "re-zero" for either configuration if I changed ammo, and then enter that ammo with appropriate offsets.
Anyway, sounds like a good excuse to go run some more rounds downrange.

 

[Deleted member 113831]

I appreciate the response, but I am going to need to think this through further. I guess I am not getting it.
Per the OP's original question, the purpose of the exercise was to be able to switch ammo "on the fly" while in the field.
I just wanted to run suppressed, or not, using the same exact ammo.
To me, if I did not save the Unsuppressed as a new rifle, I would have to manually rotate turrets to get to the "other" zero if I removed the suppressor while in the field.
What I was trying to accomplish was created an entire "line" where if I was shooting suppressed, and chose that rifle, with the SAME ammo as was zero'd with, Strelok (or whatever) would calculate my settings at various ranges. If I switched to unsuppressed, likewise so long as same ammo. I do think that I would have to "re-zero" for either configuration if I changed ammo, and then enter that ammo with appropriate offsets.
Anyway, sounds like a good excuse to go run some more rounds downrange.

I think what Racer88 is talking about is this: In STRELOK you don't have to create a "new rifle" for every load. You can simply create a "new cartridge" profile and put your offset in there. But it is the same effect, it just depends on how you wish to organize things.

 

[TomH Tx]

I think that for now I will keep my Suppressed and NOT Suppressed as separate rifles, but add any new ammo as "new cartridges" under S or NS rifle according to which I zero it under. In any event, this has been a very useful and informative thread. Thanks to all for the helpful comments.

 

[Racer88]

I think that for now I will keep my Suppressed and NOT Suppressed as separate rifles, but add any new ammo as "new cartridges" under S or NS rifle according to which I zero it under. In any event, this has been a very useful and informative thread. Thanks to all for the helpful comments.

Bingo! That should work just fine.

 

[Lawless]

Yeah, in Strelok you can add “cartridges” and name them “suppressed” and “unsuppressed” and of course add the actual cartridge name. Then the offset works like gangbusters.

I have already been experimenting with my Kidd and all the different 22 ammo I have.

This past spring I shot it out to 400 yards and had I known about the offset and how it works I could have had it already done for all the loads. 22 at 400 is SO MUCH FUN.