Rifle zeroing for an event: the 200 and 300m zero
Comparing 200 and 300m zeroes for 5.56x45 and 7.62x39 calibre firearms to help you make an informed choice
At Canadian Multigun we believe in shooting rifles at rifle distances, therefore we focus on 200 - 400m. The two most commonly used intermediate rifle calibres at our events are 5.56x45/223 Remington and 7.62x39 both of which can be used effectively out to 400m. In this article you will be presented with the points of impact & group size at multiple distances using a 200m and 300m zero with common ammunition loadings when using a central point of aim. We will not be discussing the 100m zero because for both calibres the ability to make hits past 200m becomes very hard due to the drop encountered.
The decision of which zero to use is of course down to you, we will only show you the information as best as we can.
We cannot cover the sheer variety of different calibres, loadings, barrel lengths, heights over bore, and so forth. The information is based on a 6.5cm height over bore, 47cm (18.5 inch) barrels, and the following loadings:
Federal American Eagle 55gr FMJ 223 Remington
Chinese surplus 123gr FMJ 7.62x39
In addition the references to holdovers are rounded up. No one will take value from being told they should aim 7.65MOA high, the aim of this article is to provision you with the information needed to achieve hits on a full size IDPA silhouette target as shown in the diagrams .
BUT! We rarely use full size IDPA targets at our events, the most commonly used target size out to 200m is the 1/2 size IDPA silhouette and from 200 - 400m a 2/3 size IDPA silhouette. However targets will not always the same shape, size or colour.
Point of Aim
The Point Of Aim (POA) is where you aim your rifle and is the point you compare to when looking at where your rounds impact (Point of Impact, POI).
Throughout this article at all times when showing the impact of different zeroes the point of aim that was used was as shown here. The red cross denoting the point of aim. It sits central to the centre mass of the IDPA full size target.
You will see a red cross showing on targets at <100m to denote the POI this is because at such ranges group size is of little consequence unless shooting something with an accuracy of 5moa or greater . On diagrams showing targets at 100m or greater distances a circle representing the group size and location will be used. This is based on 3moa accuracy and perfect shooter performance. i.e. There is no accounting for the degradation of accuracy a shooter experiences when out of breath, tired or shooting under time pressure vs range shooting. In addition this does not account for the reduction in accuracy that occurs with some calibres like 7.62x39 which are impacted more by things like wind past 200m than other calibres.
Knowing how you shoot while going through exercise is key to success and the shooting training mentioned in our “Physically preparing for an event” article gives you a great way to find out.
5.56x45/223 Remington
200m Zero
This particular zero at short range engagements shows a vertical POI deviation of 6cm between 5 and 50m. For most shooters this deviation will come mostly from their height over bore and there will not be a great deal of difference between calibres.
Users of bullpups in particular need to be aware that their height over bore will be greater than a standard rifle and as such will experience a greater vertical deviation than shown here.
Knowing your POI vs POA at shorter ranges is especially important when we dish out some delightfully small targets with penalty zones at shorter ranges
As you can see the 200m zero works well for making clean hits inside 300m on targets that are of a smaller size than the full size IDPA silhouettes shown. In addition when engaging targets at a distance of 300m a head or top of target POA can be used to achieve centre mass hits even on smaller targets.
Shooters should note the significant hold that is required for making hits at 400m though.
300m Zero
This particular zero at short range engagements shows a vertical POI deviation of approx 10cm between 5 and 50m. This is >66% more than the 200m zero and will have a greater impact on the shooter when engaging small targets and those with no-shoot areas.
As you can see the 300m zero works well for making clean hits on targets that are of a smaller size than the full size IDPA silhouettes shown even when shooting out to 400m. The holdover for engaging targets between 300 and 400m is not so significant as to become daunting or impractical for those without drop markings on their reticle
Shooters should note the significant deviation for POI vs POA at 100m though when engaging smaller targets than a half size IDPA silhouette or targets with no-shoots behind them that could be hit by a shot that goes high.
7.62x39
200m Zero
This particular zero at short range engagements shows a vertical POI deviation of 10.5cm between 5 and 50m. This already matches that of the 5.56x45 300m zero
Users of bullpups in particular need to be aware that their height over bore will be greater than a standard rifle and as such will experience a greater vertical deviation than shown here.
Knowing your POI vs POA at shorter ranges is especially important when we dish out some delightfully small targets with penalty zones at shorter ranges
As you can see the 200m zero works well for making clean hits out to 200m on targets that are of a smaller size than the full size IDPA silhouettes shown. But the drop of 7.62x39 immediately becomes apparent at 300m where a significant holdover is needed. At 400m if your optic reticle does not have a ballistic drop calculator (BDC) then achieving hits becomes significantly harder. Likewise those with fixed distance iron sights will have a very very hard time.
300m Zero
This particular zero at short range engagements shows a vertical POI deviation of approx 18cm between 5 and 50m. This is >80% more than the 200m zero and will have a greater impact on the shooter when engaging small targets and those with no-shoot areas.
The 300m zero certainly allows you to make hits at 300m but it also requires you to change your point of aim on targets inside of 200m. When engaging said targets it becomes sensible to place your POA in the centre of the lower third of the target to avoid shooting high. Most people when out of breath will have significant vertical movement of their reticle as they breath in and out. As such using a lower point of aim will help mitigate the impact of this with zero.
Unfortunately again an adjustable set of iron sights or a BDC reticle really are the best ways to make hits out to 400m consistently with this zero
Final Comments
All the calibres and zeroes we have shown here have their own pros and cons. With 5.56x45 as you move from 55gr to 62gr, then 69gr and finally 77gr your trajectory is likely to become less flat, but it’s also less impacted by wind. For 7.62x39 users the vast majority of loadings are of a very similar ballistic nature. For you the challenge is going to be making hits past 200m, a BDC is highly recommended.
The best zero you can have is the one you have practiced with at all reasonable distances. In the same way that high quality gear can be beaten by well trained shooters with affordable gear it is also the same with zeroes & calibres. The shooter who knows their gear and how it will perform will always do better under stress.