Thread: How to do duel Zero. Sub/Super

Im hoping to Run two loads thru my 308 one super and one sub

Iv heard a few people able to do this and I am curious to know How they have achieved it

I believe you could do it in a fashion if your scope has a zero stop as well as a zero adjustment.... set up the zero stop for the fastest dropping round ...and the dial for the flatter round... and keep your wits about you when changing from one to the other

Its kind of irrelevant, just have a known zero for both with two drop charts. You can change the zero distance for both loads.

Originally Posted by Bill999

Im hoping to Run two loads thru my 308 one super and one sub

Iv heard a few people able to do this and I am curious to know How they have achieved it

I'm currently attempting something similar with a 300 BLK pistol. I'm using a Holosun red circle dot which has proven to not be the best reticle for the job. At 50 yards, I've got about a six inch drop from Hornady 120gr super bullseye to 220gr sub point of impact. And not just drop but also some right drift for some reason???? There's just nothing in my reticle I can use for that drop, so I've got to rethink it. I'm just not willing to spin a red dot to make this work.

If you're willing to spin, it's easier. Just make 2 dope charts. Mark one at your zero stop and the other with nail polish.

I could totally do a 45 degree canted rail for the sub with a red dot but thats not really what I was hoping for

Originally Posted by LBD

I believe you could do it in a fashion if your scope has a zero stop as well as a zero adjustment.... set up the zero stop for the fastest dropping round ...and the dial for the flatter round... and keep your wits about you when changing from one to the other

Wrong way around

Set up zero stop for the super sonic load
Dial up for the sub sonic round as it will need all the dial up you have.

I run subs and supers in my 308
Zero stop is for the 308 / 125 accubond / 2950 fps load at 200m zero and its own chart out to the last moa on the Zeiss Z5 scope
Subs are 90 grain XTP pistol bullets and 13 moa on the Z5 dial gets me out to 110m

Range finder is essential and my subs chart is in 10m increments as the dialing up is critical for good hits due to the rainbow trajectory.
Accuracy with the 90 XTPs and Trail Boss is minute of hare at 100m.
I use it to feed my dog handy hares when I don't want to disturb any game animals in the area

Get a scope with a BDC reticle and see which marks match up with the subsonic drop at different ranges.
I think dialling with two different loads will end up badly at some point.
I tried sub loads in my 7/08. With my scope on 7x the thin/thick crosshairs transion on the vertical cross hair was spot on at 100yds for the sub loads. At 20yds I was 2" low and at 50yds about 4-5" low from memory.

problem with using a reference point in a 3-9x40 is the recticle has to be on a set power eg. 3 power to be the same each time, it will be different on 5x or 9 power

unless you have something fancy and FFP

I have my scope zero'd at 100m for the supers (300BLK).

I dial up 6 on scope for a 50m zero for the subs.

I prefer to use the point blank (or blanc) method for zeroing. Which gives me a relatively flat arc to the zero that never deviates more than 1" high or low.

For dropcharts I use Strelok on my phone.

For scopes I use a Nikon Monarch 2-8x32 BDC (and on my .22lr a Nikon P300 2-7x32 BDC).

Tip for drop charts, I write significant the drop points on my scope on my wrist with a marker pen before a hunt.

The method I use is a simple Mil dot type retilcle, Then rather than do a drop chart and adjusting I simply work out the confirm what ranges the dots are for the two ammos.

EG with my 303

Load 1 Zero is at 100m and is the next dot down at about 175m (Big RN slow bullet like throwing a hammer)
load 2 is zero at 150m and the second dot down is at about 225m. (Lighter faster bullet)

If I look to what load I have in I know the distances that this load matches the marks on the cross hair. So I do not need to adjust anything regarding my scope. I just need to know what ammo is being used.

Another area where mil dot reticles shine, just need to be careful with sfp scopes to use the right magnification.

A zero stop dialup scope is the most accurate system for me in a subsonic dominant 300 blackout. My subs are set on turret zero with a zero of 60m as that’s the average distance I’m shooting and just dial up the required distance as you would on a normal rifle.
The supersonic zero is set on the zero stop which is 9 MOA high for a 100m zero and dial the MOA needed for whatever distance.
I’ve been using this system for the last 4 years and it’s easy to use, just remember what ammo your using.
Sometimes I use the reticle if I have got time to dial.

My 308 is zeroed for 150 metres with ful lpower loads and the subs are 50 metre zero where the post on the scope thins

I go a step further and use 1 scope for 2 rifles (super/super and sub ammo) - one rifle is at zero zero and the other rifle and it’s 2 loads have separate charts

Originally Posted by timattalon

The method I use is a simple Mil dot type retilcle, Then rather than do a drop chart and adjusting I simply work out the confirm what ranges the dots are for the two ammos.

EG with my 303

Load 1 Zero is at 100m and is the next dot down at about 175m (Big RN slow bullet like throwing a hammer)
load 2 is zero at 150m and the second dot down is at about 225m. (Lighter faster bullet)

If I look to what load I have in I know the distances that this load matches the marks on the cross hair. So I do not need to adjust anything regarding my scope. I just need to know what ammo is being used.

Here is a diagram of what I mean. I have simplified it a bit as while load 1 on my rifle (primary factory load 180gr doing 2700fps) is set at 40mm high at 100 metres which gives me a 200 yard zero and peaks at about 60mm at about 150m. My heavy hand loads which a re a 215gr RN SP doing 2076fps are peaking at about 40mm high at 75m with a 100m zero and fall like a stone there after. (It is only coincidence that they peak at about the same height, but it would not matter if they did not. The Sub load would peak a wee bit higher and further away if I push is out faster....)

175m is about the same low as my 250 metre point for my 180s.

I have lined up the mil dots on my diagram for illustration purposes as my scope is a little different. Rather than adjust the scope for elevation I just understand that these points are where each round passes at a known distance and that the distance is different for each of the two loads. I do the same on my 22LR for suprsonic and subs. (Zero'd at 50m for the subs and is about a 75m zero for the supers without adjusting the scope.