Subsonic DOPE with super zero

[Nate4641]

I worked up a subsonic 308 load for fun with trailboss and I'm getting good consistency around 1070fps. I have a decent group at 100yd hitting about 13in lower than my zero for my standard load. I don't have access to a range with more than 100yds at the moment so I unable to get verified drop data past that, and I had a couple of questions on how to use a computer to figure out drop at longer ranges. I'm using Ballistic AE currently. I have a solid load developed for this rifle and don't want to re-zero the scope every time I plan on throwing a few subsonics downrange.

1. Is there a way to tell the computer that my zero for this load is impacting at a different spot than where my scope is zeroed? Like is there a way I can tell the computer to re-adjust 100yds to show 13moa and it'll correct for any other distances?

2. If I can't re-adjust 100yds to show my drop on the computer, can I just add 13moa to all the values it gives me, or is that not how this works?

3. How big of a change should I expect my BC to be in actuality since I'm shooting these bullets subsonic vs their intended super sonic speeds? I imagine the slower velocity has to play some factor in that.

 

[WVLR2000]

Should be able to change your zero height to how ever low its hitting and that would make the computer think its zeroed there.

 

[Huskydriver]

How far you trying to go lol? I shoot at 400 pretty regularly and it's not easy.

Subsonic 308 is enough drop at 300 to max out the travel on alot of scopes.

The computer doesn't care where your physical zero is. Put in the data for your desired load and dial 13 moa to start plus whatever come up it spits out at you

 

[Nate4641]

How far you trying to go lol? I shoot at 400 pretty regularly and it's not easy.

Subsonic 308 is enough drop at 300 to max out the travel on alot of scopes.

The computer doesn't care where your physical zero is. Put in the data for your desired load and dial 13 moa to start plus whatever come up it spits out at you

I'd like to go as far as I can lol. I've got a razor gen 2 4.5-27 on the rifle so with the turret maxed out and using the bottom of the reticle, I should have about 106moa to play with. That should get me out to at least 600 if my math is right.

 

[FishDr]

Depending on which solver you’re using, I add a zero offset to the computer (in my zero data section) and it does all the math. In essence, it just does exactly what you describe - it adds the 13MOA (in your case) to the firing solution. I just pick a different curve when going to super, dial the right dope and fire away.

 

[Doc68]

What @Huskydriver said. I use strelok pro and as long as you zero your scope to 100yds and go from there. The computer only knows what you tell it.

 

[atepointer]

I think I understand what you are saying, but not 100 percent so I'll share what I have done. I run 7.62x39 subs. I zero my supers at 50 and zero reset there and since I knew the bullet drop out of level barrel at 100 was 13" for subs I just dialed in 3.5mils from 50 supers zero and was close enough to tweak. So, all I do now is set my sub ballistics zero at 100 knowing whenever I shoot subs I come up 3.2mils and I'm on at 100 for my starting point.....so looking at elevation turret with a sub in the chamber it says 3.2, but I know that is 100 'zero' for subs.. If I want 200 yards I go up another 4.1mils so on so forth from ballsitics calc. When I'm back to supers I put elevation turret at 0. Make sense?

 

[Nate4641]

I think I understand what you are saying, but not 100 percent so I'll share what I have done. I run 7.62x39 subs. I zero my supers at 50 and zero reset there and since I knew the bullet drop out of level barrel at 100 was 13" for subs I just dialed in 3.5mils from 50 supers zero and was close enough to tweak. So, all I do now is set my sub ballistics zero at 100 knowing whenever I shoot subs I come up 3.2mils and I'm on at 100 for my starting point.....so looking at elevation turret with a sub in the chamber it says 3.2, but I know that is 100 'zero' for subs.. If I want 200 yards I go up another 4.1mils so on so forth from ballsitics calc. When I'm back to supers I put elevation turret at 0. Make sense?

Yeah I get what you're saying. Thats kind of what I was thinking I would have to do.

I did some playing around on Ballistic AE and for my sub load I changed the Zero Height setting to a negative value. Weird thing is, even with me saying at 100yds the zero is -13", the chart shows a slightly different value. Played with it a little more, and now at 100yds it shows what my actual drop was. Theoretically the rest of the chart should be set up now. I'm waiting on a membership to a local range to go through, and I'll be able to test it out to 200.

 

[atepointer]

There may be a better way I dunno, but it works like a champ so far. If I'm plinking subs I just dial 3.2 and keep adding chart dope on the way out to that 3.2. So while my sub chart says 4.1 mils for 200 I know it's actually 7.3. Really looking forward to taking it back further to see where it craps out but smacked the 4" popper a few times in pretty good winds at 200 so hopeful.

 

[Doc68]

Just zero your rifle at 100 or 50 with subs and plug your numbers into a ballistics calculator. Go from there and enjoy the plinking.