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I called Primary Arms to ask that same question. Since they made the ACSS reticle I thought it made the most sense to call them. They told me I needed to buy the strelok app and chronograph my specific gun/ammo to figure out what yardage to zero in-order for the ACSS to work properly. I wish they would publish the data for us so we don't have to buy a chronograph and ballistic calculators but it is what it is.
yes it's a very big difference. The bullet weight will also make a difference besides the barrel length. What you need to know is how fast your bullet is going. then you can compare it to the truck that they give you.
the most common speeds are:
556 & 308 ~3000 ft/s
7.62x39 ~ 2,000 ft/s
22lr & 9mm ~ 1,200 ft/s
so if you're short barrel AR-15 is going about the same speed as an AK-47 round, you use that chart to figure out your drop rate.
look up the drop rate chart for holosun 503g to see what I mean
I am going down this same road. I am planning on using this with a vortex micro 3x magnifier on a 7.5" 223. I am an avid long range shooter and reloader, so I decided to look into this to see if the BDC would be useful. This is what I found. Using a hornady 55gr soft point bullet at 2400fps, 60°F temp and 29.92" Hg, with a 150 yard zero the first dot is approximately 295 yards. The second dot is approximately 355 yards and the third dot is approximately 420 yards. The barrel length is greatly going to effect the velocity of the bullet and in turn effect the BDC. A chronograph and ballistic calculator is imperative to verifying velocity and calculating the bullet drop in different ambient conditions.
Yes it will make a big difference. I shoot long range and have the ballistics AE app. I would suggest it as it is a great app for a ballistics calculator. I put this on a 7.5” barrel. Running a hornady 55gr soft point at 2400fps a 150 yard zero. Ambient conditions 81.7 degrees F and 29.94” Hg. The first dot will be approximately 295 yards. The second dot will be approximately 355 yards. And the third dot will be approximately 420 yards. Lots of things will effect the yardage. Having a chrono and ballistic app will help you with the drops. Hope this helps!
You don’t need to buy a chronograph. Zero at 100 then do a tall target test, you should be able to figure out your needed zero by doing a little math, for any Ammo. You will get so close it won’t matter. To make it real easy, download any quality ballistics app, for ex, mil dot ballistics and enter the velocity and it will literally calculate it out for u in inches of drop. MDS may even have this reticle in its ret library probably only going to shoot that short barrel at fairly close range anyway! Remember it’s a CQB ret.
With a 7.5" barrel, the "accuracy" is too sporadic to publish a credible ballistic guide.
My 12.5" grendel was dead on with the primary arms brand version of this sight out to 500yd with a 3x magnifier. I also thought the zero and drops would change in a short barrel, but for the grendel the change is negligible. YMMV
Yes, the app Strelok or Strelok Pro can let you enter your ballistic information for each box of ammo you use and it will show you where your rounds will hit at different ranges. Call the ammo manufacturer if you have any questions about the ballistic information needed
Federal m855 62 grain 5.56 mm out of a 7.5" Barrel at 500 yards has approximately a 14 inch drop. Ie; if you are aiming for between the eyes on a silhouette target you will hit center of chest at 500 yards. Hopefully that will help you with figuring out the ACSS for you situation.