Truing Strelokpro with suppressor/cover

[arrowem]

I was zeroing my rifle for a prairie dog hunt and I got to thinking about the "truing" aspect of strelok. First I only have a 400yd range but plan on taking shots probably twice that so I can't true at that distance. I zero for 200 with suppressor. I then go to 400 and of course it shoots lower than strelok predicts due to the weight of the can. I true it so it matches reality. I then added a can cover to help with mirage. I shoot 400 again. even lower( expected).
So here is what got me thinking about "truing" . When I "true" it, it will recalculate a speed to correspond to the drop. If I plug in 800yds it will use that recalculated speed. The bullet is not actually going slower because of the extra weight at the end of the barrel. If the weight makes it shoot 6" low at 400 then is it the same 6" lower at 800 or is it the same as the "recalculated" speed. i.e. 6 inch drop without suppressor at 400- 12" with...110" drop at 800yd-116" with.

 

[pell1203]

arrowem, how much lower is it shooting than the predicted drop?

I would check all your inputs to the ballistic calculator as you've likely got something else going on here. The weight of the suppressor has nothing to do with your rifle shooting lower at a different distance once it has been zeroed at a specific distance. Make sure sight height over center of bore is accurate and is entered in the correct field in the calculator. Some calculators have a sight offset field which is often confused with sight height.

The vertical drops downrange are mostly dependent on gravity, BC of projectile, initial muzzle velocity, and current weather (pressure, temperature, humidity) differences between your zeroing conditions and current shooting conditions. All things your ballistic calculator will account for. This assumes you have no odd wind updrafts/downdrafts and your ammo/powder temperature is consistent from one outing to the next.

I would suggest you zero at 100 and then use your ballistic calculator to get you out to further distances, By zeroing at 100 you take out most environmental variables out of the equation.

 

[arrowem]

Thanks. I will go and check everything again. I wasn't thinking that once you zero, the bullet behaves the same way as long as nothing else changes. Thank you for "fixing my clarity"

 

[lash]

How did you determine the speed of your projectile that you entered in Strelok? As mentioned by pell1203 above, if your drops were off by 6" between 200 and 400 yards, then something else big is going on. If you plan on using that suppressor much, you most certainly should find out if there is a difference in POI between with can and without can, then zero your scope/rifle at 100 using the can if that is what you will be using at the prairie dog hunt. Then check you dope at 200 and 400 and see if any truing is required.