I also played around with trying to find an adjustment table.

Oat said the gun was zeroed at 50 yards, so that’s what I used, plus the height of a CompM5 on my MCX at 3.3 inches.

One of the loads listed in the scope’s manual was Barnes 110 grain TSX bullet at 2400 fps; its G1 BC is listed as 0.264.

When I ran that with the Applied Ballistics solver, I got these trajectory figures from the line of sight:
100 y: + 1.58"
200 y: – 1.54"
300 y: – 15.43"
400 y: – 44.01"
500 y: – 92.54"
600 y: – 167.17"

I then ran the Barnes TAC-TX at 2030 fps; G1 BC 0.289. As I ran the figures I looked for trajectory values that matched the ones for the different range marks for the first 2400 fps load. These are what I came up with.

100 y: No exact match. The trajectory of this load was + 0.90 at 100 yards, so very close to the first one and I would disregard the difference.

The first figure is the reticle marking. The second is where this load would actually hit with that hold. I.e., if using the 200 yard mark for aiming, it would hit a target at 158 yards.
200 y: 158 yards
300 y: 253 yards
400 y: 347 yards
500 y: 441 yards
600 y: 537 yards

All calculations were made at “standard” atmospheric conditions: 59°, 29.92" station barometric pressure, 0% relative humidity. Changing any of those values would have an effect on all that, but very minor.

I would be curious to learn how close my figures were to Oat’s.

Added: According to the AB solver, with a 50 yard zero Oat’s load’s second zero point would be at 133 yards.

This message has been edited. Last edited by: sigfreund,

quote:

Originally posted by Oat_Action_Man:
So Strelok+ is the app I was looking for.

Went and downloaded it and...whew, that's a lot. Seriously, are there instructions??? I'm a dolt.

I think came up with a solution for the SFP ACSS 1-6x 300 BLK reticle for my 9" MCX using Gorilla's 110gr TAC-TX load. When I chrono'ed it myself, I got a 5 round avg MV of 2030 fps from my 9" barrel (suppressed). Gun is zeroed at 50 yds at 6x, per the Primary Arms instructions.

The bullet library didn't have the Barnes TAC-TX so I had to choose the 110gr TAC-X.

The reticle Strelok provided seems reasonable for the load out of a short barrel (50 at the tip of the chevron, 145 at the inside vertex of the chevron, 456 at the 600 yard hash), but I'm largely out of my depth here.

Some questions:

Did I totally mess that up?

How do I actually get it to input an avg velocity of 2030 fps? It requires 2 velocities and somehow spits out 2018 fps??

Did I miss the TAC-TX in the bullet library?

What's G7 vs. G1 coefficient? I used the latter.

What's my far zero? It doesn't seem to list anything on the reticle (aside from 50 yds tip of chevron) and I don't see a full ballistic table option anywhere.

Is there a gun/reticle/load library I can save this solution to? I send a pic of the reticle to myself, but inputting the data is a pain.

Is there an instruction manual? I didn't see anything in the settings menu....

I’ve been using iStrelok for about 5 years, it has worked well for me.


Go to the settings tab, click on about iStrelok, from the page that pops up click on visit web sight, there you will find instructional videos as well as a manual.

From this page you can also email the app creator, if you have the ballistic data for a bullet that is not in the library, he will generally add it, same goes for scopes, he will ask you to provide the parameters of the reticle. I emailed him about a scope I had about a year and a half ago and he added it after I provided the reticle information. It takes awhile but he’s pretty easy to work with.

As to velocity, the app will change the inputted figure depending on elevation and weather conditions. Not sure if there is a way to turn this off.

Thanks for the input.

I was fiddling with the reticle view last night after finishing up a carbine class. Things became a lot more sensible once I changed the target view to a standard IDPA silhouette and dicked around with the range and magnification setting. The holds became much clearer once I did that.

I'll be using the rifle with the optic in question at a class this coming weekend and will see how it works out. I had previously shot from 3-20 yds to measure the mechanical offset, so at least I have that data already.