H & S Project Rifle part 6 – Field practice & validation.

With some fine tuning to my hand loads I had the rifle shooting small groups at 100 yards. The question now is how will this combination of rifle, scope and ammo go out in the field at longer ranges?

The target shown above is made from AR500 armour plate and was hit with the project rifle shooting 180 grain Berger VLD bullets. Range was 522 yards. Only the paint was marked on the plate and all bullets were vapourised on impact. All field shooting was done laying down in the dirt with a front Harris bi-pod and rear bean bag.

To make consistant hits like this at any range, you need to validate your trajectory. To do this you need to shoot the rifle at a number of different ranges right out to the maximum range that you intend to use it.

In this case I had a 100 yard zero and my maximum intended range was 1000 yards. I placed a couple of random targets at 522 yards and 618 yards and fired three shots at each range. I used the Exbal ballistic program to determine the amount of dial up that I would need with the Bushnell scope.

Now this scope has about 5% error in its elevation turret. This complicates things a bit as I would be getting more elevation than what I wanted.

The photo above shows a 4 inch group shot at 618 yards. This was my first group shot with this rifle at a range longer than 100 yards and it obviously hit a bit higher than I calculated. At this point the weather turned for the worst with very strong wind and rain. So I placed an orange clay target out at 1000 yards and sent a few rounds down range to check for drop.

The wind was blowing my bullets about 3m to the right of target at this range so I recorded the drop require for elevation and went home to think things through.

Computers with ballistic programs are interesting things. You can play with various inputs and see what sort of changes are made to your trajectory. Now that I had some real life data to play with I altered my velocity upwards from 2830 fps to 2900 fps. This has the effect of reducing the dial up required and should be a better match for the actual dial up observed. Now this was needed to correct for 5% scope error. This was the equivalent of 1.5 MOA at 1000 yards.

Another option would be to input a different B.C. for the bullet that I was using. Time will tell if this is needed. It can be a useful option if your trajectory aligns with the 100 yard zero and 1000 yard impact but is out slightly at intermediate ranges.

With this correction made to my inputs I went back out into the field and between showers took three shots at the AR500 plate. The results can be see above. If the condition improve over the next few days I will head back out and repeat the process and validate the trajectory right out to 1000 yards. This process is also invaluable practice.

Anyone after an AR500 steel target drop me a line. They are not cheap but they are good.

Related posts:

1. 2010 HUNT & SHOOT Project Rifle – 7mm Rem Mag. Part 1
2. H & S Project rifle part 2 – Fitting the Picatinny rail
3. H & S Project Rifle Part 5 – In search of accuracy.

Category: Norman Nelson's Column