Shooting a load

Last weekend I made some ammunition for the purposes of load development which is a process I go through to create an accurate and consistent rifle round for various purposes. I did a video that you can watch further back in my blog if you're interested. Today I thought I'd expand on the concept of load development a little and whilst it can get quite technical I'll endeavour to make it understandable to those who may be interested. For those who may understand reloading and load development it may read a little basically, however I'm hoping it comes out somewhat understandable to those who know little, to nothing, about the process and how it works.

It may be necessary for me to define certain words or terminology in the course of this post which I will do of course however if anyone has any questions click the reply link and shoot it my way.

The term load refers to the amount of gunpowder inside the rifle cartridge and depending on the amount of powder the ammunition will shoot differently. I will not get into the technicalities of it as I'm not a ballistics expert however finding the right load is critical to accuracy and consistency; Two things a precision shooter will always chase. Muzzle velocity, which is the speed at which the projectile exits the muzzle, is also important so finding accuracy, consistency and a fast load is often what we seek. Oh, safety is also paramount of course.

Gunpowder...There are many different powders available, all of which have different qualities such as faster or slower burning for instance. It's a very technical thing of course, and even the shape and size of the individual granules of powder can make massive differences to the overall outcome. I won't go into it here as the post would be a very long one however to assist those like me who make their own ammunition, called reloading, it's important to know which powders to use in each application.

There is reference data available to assist in this process and so the first place to start is there. Different powders are used for different calibre's and projectile weights and there are literally thousands of combinations. For my purpose though I use ADI 2209 for my .243 (6mm) calibre and so refer to that data for correct minimum and maximum loads. Exceeding these specifications is possible at times. It can be deadly though, and so needs to be done with caution. I have done so on occasions, when in pursuit of the ideal round, but not often though.

So, developing the load is to find the best round for the job and it's done by adjusting gunpowder charge inside the ammunition through adding or taking away gunpowder. That's it in a nutshell. But how do we know what's good and bad? How do we end up determining the actual load to use? We go and shoot the rounds of course!

After determining the minimum and maximum suggested loads for my ammunition I went ahead and reloaded the rounds which would end up being shot in test firing process. I loaded them in increments of 0.3gr (grains). Just so you know, 1 grain weight is a very small measurement. It is in fact 0.00228571 of an ounce or 0.064798788502044 of a gram. It's small. Photographed to the right is three granules of gunpowder (2209) next to the tip of a standard ballpoint pen. It demonstrates how small an increment 0.3gr actually is.

I loaded starting at 40gr. So: 40, 40.3, 40.6, 40.9, 41.2, 41.5, 41.8 and 42 grains. I did not want to exceed 42gr at this stage just yet. I made 3 of each for a good representation of each load when being tested and the ability to see a clear average. Each batch is then numbered, in ascending grain-weight order, for later reference. So, I made eight batches of three rounds [each grain-weight] totalling 24 rounds in all. Considering I am looking for data it's important to ensure I could identify each batch once fired down range so they were clearly labelled with their corresponding batch number. Once done it was time to shoot so I headed out to a mates property for some testing.

The equipment needed to do this is the rifle the load is being worked up for, a bipod and rear shooting bag for stability, correct targets, paper, ruler and pen. The idea is to remove any negative-input the shooter may have on the shot so the data is as good as possible, that's why a stable shooting position is required.

We set up the targets, three of them, at 207m (679 feet/226 yards) and got started. The reason we use this range instead of the usual 100m range at which most guns are sighted (zeroed) at is that we want the bullet to have the chance to travel and expose any weakness, or strength, along the way. At 100m there's not enough time for that.

For example the flight time of my .243 rounds to 100m is only 0.12 seconds and 0.15 to 200m. For comparison flight time to 500m is 0.71 seconds and to 1000m is 1.92 seconds. Flight time at long range is why the turning of the earth (Coriolis effect) needs to be factored into the field firing solution (FFS)...This data is calculated by ballistics calculators and a lot of information is required to get it. I did a post about StrelokPro a while back which explains. heck that post out here if you are interested. It's a long one too!

OK, so I'm set up ready to shoot in a very stable, prone shooting position. Beside me is my spotter with a high-powered spotting scope (50x magnification) so he can see the fall of each bullet on the target. My spotter has paper and pen and has drawn up a copy of each target I'm shooting at (all exactly the same) so he can record the fall of shot after I fire each one. I'll shoot each string of shots and then allow the rifle barrel to cool as we discuss them.

So, this is what's called a ladder test although technically it's not a true ladder test. It's similar I guess. I'm shooting for elevation is what it means essentially, not necessarily looking for amazing groupings. Every gun, even those of the same make, model and calibre will shoot differently, even if they have come off the same production line side by side. So, what I'm looking for here is a load for my gun right? So, I'm looking for the round that is consistent, in elevation and grouping but at this stage elevation is the key.

Most guns, and ammunition, will throw out what's called a flier which is why we shoot three rounds to gain an average. Unfortunately the conditions were not perfect for our test on the day with a reasonably unpredictable wind coming from 7 o'clock swinging to 8 o'clock, so over my left shoulder and behind me, although it was still satisfactory and we proceeded.

Chasing elevation is what's important, essentially rounds falling as close to a horizontal plane as possible. Those that go high or low indicate poor rounds...Those falling close to that horizontal plane are better. Simple.

The images below show my targets.

This is all three together at 207m as mentioned above. The grey circle you see is 30mm in diameter (1.18 inches) so reasonably small at that range. I shot them in left to right order.

Where I do things a little differently is in the order I shoot the rounds. Rather than shooting each batch of three, say all three 40gr rounds in a row, I shoot one of each of them in order of lowest to highest grain-weight and all at the same target.

So below (the left most target) you are looking at 8 rounds in grain-weight order: 40, 40.3, 40.6, 40.9, 41.2, 41.5, 41.8 and 42 grains. The second (middle) target is the same again and the last (right) target is also the same sequence of shots. My spotter records each shot, where it landed in respect of the grey circle, on the sheet in front of him like plotting a map I guess. Each shot is numbered #1 through #8 on that map for reference later.

As you can see the first and last targets are better groups with the middle being the worst. That's because the wind picked up. (Not that I'm a shit shot.) This is why three rounds for each load are shot. It means we can eliminate the worst if required. In this case we used it to simply confirm the fall of shot as each number of round from each batch actually landed roughly in the same zone on the middle (windy) target as in the other two targets. The group is just bigger is all.

Here's the left target close up. See they are all quite nicely placed along a horizontal line? The one of the extreme left and the extreme right are fliers as mentioned above but are still on a good horizontal plane. Each were numbered #1 - #8 and we moved on.

Here's the right side target, the sequence of rounds I shot. See the one low between the little black dot and the great circle? That's a flier as is the one at the top that stands out by itself. We knew that not every batch of three rounds would shoot well and as expected the ladder test identified very clearly the best and worst. Once the shots were fired we started collating the data and comparing, in this case, the right and left targets and where each shot landed. We look for each #1 bullet hole across the targets, each #2, #3 and so on (these numbers correspond to the grain-weight of each three round batch, remember?

The idea is to find a couple loads that are better than the rest. We found two of them and will conduct further testing on them to more accurately define which one is the winner and will be declared the load for that rifle and projectile-weight combination.

We decided batch #4 at 40.9gr and batch #8 at 42gr performed the best and so they will get tested again. I'm also going to load a 42.5gr batch to see how that goes. I am doing that to see if I can find a load with greater muzzle velocity as speed improves trajectory and the delivery of energy into the target which, if it happens to be something I intend to kill, makes it more humane. This is important for my culling work. In a competition many look for a lighter (slower) round to reduce recoil. My rifle is set up to handle recoil though and it's comfortable to shoot even with a very hot load.

If you recall, there are maximum and minimum loads suggested and as the amount of gunpowder is increased so does the pressures exerted on the case and rifle. Too much and...Well, that could end badly. With each test firing I check for pressure signs which show around the primer. None of my rounds showed any signs of excess pressure hence my decision to increase the load a little more in search of muzzle velocity.

Phew, ok so that's a whole lot of mumbo jumbo to most people and I'd be really surprised if anyone is even still reading this post. I guess that through the odd post about the intricacies of reloading, and other's I've done on the skill of shooting itself, someone may look upon the hobby of shooting with a different opinion. Shooters tend to receive a little bit of flack sometimes, some of it is even deserved, however many of us are just normal people with a hobby. Quite obviously it's a hobby that requires a great deal of skill, patience and some technical ability...It's not all just shooting cans and road signs...In fact for many it's never been about that.

My load development continues and I'll be making the follow up rounds on Saturday ready for next Thursday's follow up testing. Once that is done I will also true the data in my ballistics app StrelokPro. This means I shoot the rifle out to long range, say 300m, 650m and 900m and record, in the app, the actual amount of elevation input [in MRAD] I've dialled on my scope to impact the targets. That ensures the data is trued. This will also give me muzzle velocity being achieved.

So, as you can see it's a fairly complicated process and this stuff takes a long time to know and master. I've done this many times for different calibre's and guns like my .308, 6.5mm Creedmoor, 22.250 and 7mm as well. This process needs to be done all over again if a change of projectile is made, change of cartridge brand etc. Yeah, I know...It's complex. Anyway, I'm almost there with my .243 and you'll be happy to know this post is...Now (almost) over.

The rifle on the same day as the test pictured below. (Spotlight fitted to right of scope as I was out culling when I took this on Thursday night.)

Tikka CTR Stainless steel (.243)
Custom carbon fibre stock (bedded)
Little bastard muzzle brake
Atlas bipod
Kahles 624i (6-24x56) scope (SKMR3 reticle)
Accuracy 1st scope level
Vortex back up bubble level
Nitecore MH40GTR spotlight

Here's me watching a target on Thursday night. In that green circle I have drawn is a kangaroo tempting fate on the wrong side of the fence. He had just crossed it and I'd been watching him to see if he had any friends. He didn't and so I did my job. The range is 199m exactly. Ranged on my Bushnell Elite 1 Mile ARC ConX laser rangefinder.