Best way to go about shooting multiple groups

Good afternoon Team,

I have ladder loaded 5 different powder weights with 4 rounds for each weight and will be shooting them hopefully this weekend.

This is my first time testing reloads and am unsure on the best way to go about shooting the groups.

Do I need to let my barrel cool bettween each shot? Each group? And how much should it cool down?

Should I be shooting them over a chrono while i test the accuracy of the loads? Or is it best to find the most accurate load and then test the speeds of just that powder weight?

This being my first time I obviously have no experience in this field so any additional information that you guys think may help me will be awesome.

Cheers, 7RMBoy.

Yes to a minute cooling between shots.
Chrony is helpful but not essential initially.
Recorde each shot poi with its matching load data.
Do not adjust sights between shots.
Better at 200 than 100 m.

Why is it better to shoot at 200 compared to 100?

You will get a better picture of differences shot to shot.

Shoot them over a chrony. On many occasions with the start of load development I have ceased firing a load after only a couple of shots when the velocity wasn't what I was expecting (ie too low).
Sometimes I have even scrapped firing the next load increment up and progressed to the 3rd.

If you are shooting something hot the less rounds fired the better so combine group (or ladder) and velocity testing. (Although most hunters probably won't burn out a barrel, barrels do have a definitive life and each shot fired is a shot towards the end of the barrels life. I try to minimise shots fired.)

With sporting weight rifles (read whippy barrels) yes, you need to wait between shots. Most of my stuff is now truck axle barrel dimensions so I just shoot my 5 shot group and then take a wee spell before the next. Might only be as long as resetting the chronograph for the next series and having a quick drink. Keeping a check on barrel temp though out.

Also consider round robin shooting - ie 1 shot from each load across 5 target aiming marks, then the 2nd round from each load and so on. This will even out the effect of heating (a bit) and average fowling effects. You'll need to fire a shot and delay before the next if using this method.

Cheers Zimmer, i like your first point about skipping groups. I loaded from the min to max off of a Nosler Reloading chart going up in .5gr increments so I roughly know what i should be expecting speed wise. Only thing i have changed is the C.O.A.L. mine are at 3.350” and the load data for the weights and speeds were at 3.290” for the 160 accubonds out of a 7rm. Should i be expecting faster or slower speeds with this increase in C.O.A.L.?

I’m shooting a Hell’s Canyon Speed so the barrel will probably heat up quite quickly.

If you havent jammed the bullet into the rifleling it is likely you will have lower pressure and velocity. BUT; if you have jammed you could get high or even very dangerous pressures.

When setting my C.O.A.L. I jammed and measured it to be 3.366”. Backed it off to 3.350” for the loads

With 16 thou" yr probably safe and may get lower pressures. Bullet type, case type, primers and powder batch lot as well as the characteristics of your rifle can all affect the outcome though. As the recommendation go; start low and work up carefully all the while looking for pressure signs. Extractor mark or sticky bolt lift means alarm bells.

Will definitely make sure to keep an eye out for any pressure signs. Cheers Woody

Each 4 shot test is only 1/2 grain up to he will still get a ladder. One other suggestion is that sandbags are used for consistent support both front and rear in order to minimise shooter error.

300 m or so will give you a clear visual separation of bullet holes and therefore show you which node is the preferred one. The addition of a chrony will reinforce what your target is telling you. You will probably end up with 2 or 3 loads that produce similar speeds and are close together on the target. This is your starting point and from there, as has been said, you can alter seating depth to try and improve the group size.
I tend to use .2 Gr variants but no reason why .5 variants wont work, as long as you know how to recognise signs of pressure.

Definitely wait 4-5 mins between grps to allow bbl to cool. When firing grps I just run 3 and don’t wait much between shots.
If you are starting at the very bottom of the load manual range then you will alomost certainly be wasting time and components. Load data provided is very conservative. Especially given your COAL is much longer than SAAMI. As others have stated best approach is to first run a ladder, single loads working up to book max. If you know how to read pressure signs then can usually go 1-2 gn above book max in magnum calibres. 0.2 or 0.3 gn increments is better than 0.5 for this step. Watch carefully for pressure and if your not sure get some one to join you who does and get them to show you what to look for. Once you’ve established safe max and based of your ladder data ( as @Mauser308 explained) you can pick a likely sweet spot to fine tune optimal load with groups.

One point, everyone seems to shoot ladder testing at the same aiming mark with the results being on a vertical plane. There is no reason at all why the test cannot be done horizontally using a string of aiming marks. I have read of top shooters overseas (well, those that ladder test) doing this. If restricted to shorter ranges eg 100yds (not everyone has access to longer ranges) the issue of confusing bullets holes is not such a problem.

The use of a chronograph will also give an indication of the almost linear increase in velocity with each charge increase until of course the bottoming out that occurs up higher.

Greetings 7RMBoy,
Load testing can be as simple or as complicated as you want it to be. For a start it is best to keep it simple. You have 20 rounds ready to go so start with them. Definitely chronograph them as this will tell you where your combination of projectiles, rifle and powder lot sits compared with the data you have been using. This is important as data for the 7mm RM, which I think you are using, does vary considerably. I don't believe that letting the barrel cool between shots in a group is either necessary or desirable. To me any precision lost to a heating barrel is less than that lost to getting up between shots or just fidgeting while waiting. By all means let the barrel cool completely between groups. A fouling shot before starting is a good idea, remember you are testing the load. Fire each of your 4 shot groups on a separate target and mark the targets so you don't mix them up. While shooting try to keep everything the same. The recoil of each shot is likely to push you back a little so make sure you as set up the same each time.
When you get home check your velocities against the data you have been using corrected for your barrel length. As an old draughtsman I like to do this on a graph as to me it shows the relationship between the two sets of data. As Woody suggested your velocities are likely to be a little lower. You should not run into pressure signs. At this point I would select a load towards the top of the velocity range that has a reasonable group and load 10 or a dozen rounds at that. This gives you some rounds for actual hunting and enough for a couple of 3 or 4 shot groups to verify the loads accuracy.
At this point you can decide which of the hundreds of load development methods you wish to pursue. Some at this point just use this load forever and some spend countless hours on the range testing and refining their load. Neither approach is wrong and most of us are somewhere in the middle. You just need to find your spot.
Regards Grandpamac.

Hey Grandpamac, always good to have a reply from you.

Would you, like the rest also recommended shooting at a distance further than 100m? Would start to become an issue as the only spot i can access easily is only 100m.

So basically I am just looking for the batch that offers the best velocity, grouping and consistency? Once i have determined that then I can start adjusting more slightly to refine it? Obviously I want to have as tight of a group as possible with a reasonable velocity so that I can take advantage of the distance the rifle is capable of. As I have a VX-5HD for glass I will be able to eventually have a custom turret made so consistency is definitely key.

Cheers, 7RMBoy.

Quote:

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Originally Posted by 7RMBoy

Hey Grandpamac, always good to have a reply from you.

Would you, like the rest also recommended shooting at a distance further than 100m? Would start to become an issue as the only spot i can access easily is only 100m.

So basically I am just looking for the batch that offers the best velocity, grouping and consistency? Once i have determined that then I can start adjusting more slightly to refine it? Obviously I want to have as tight of a group as possible with a reasonable velocity so that I can take advantage of the distance the rifle is capable of. As I have a VX-5HD for glass I will be able to eventually have a custom turret made so consistency is definitely key.

Cheers, 7RMBoy.

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Greetings Again 7RMBoy,
I much prefer to test and zero my rifles at 200 metres. Sometimes a load that looks good at 100 metres can loose the plot at longer range, often due to marginal twist for the projectile. For initial testing however I often use my home 60 metre range for initial testing when validating the components I am using. I also use it for zeroing my old soldiers which run on light loads. You are going to need a much longer range for checking your trajectory later on. Have a talk to your local NZDA to see what they have access to.
Initially you are just looking for an acceptable load that offers reasonable accuracy and velocity so you can use it as your standard load while you are doing further development. I am still developing loads for my old .308 that I bought new about 1975 but I have a standard hunting load that I have been using for 30 years that the rifle is zeroed for. Clearly for some of us the load development goes on forever. The reason for only loading a small number of cartridges for your initial load is to avoid having a drawer full of orphan cartridges. Recent load testing for my .308 shows that it shoots very well with 165 grain projectiles but there are close to 100 rounds of my standard hunting load in the boxes. At 71 I would consider myself very lucky to use them all hunting.
Regards Grandpamac.

Hey,

For initial testing 100 should be fine then. If a group looks good at 100 is does, as you say have potential to lose it at 200. But a bad group at 100 would definitely be worse at 200. I’ll try find a spot where I can sit back further but if not 100 will have to do for now.

Cheers

100 yrds will work just fine.

Quote:

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Originally Posted by 7RMBoy

Hey,

For initial testing 100 should be fine then. If a group looks good at 100 is does, as you say have potential to lose it at 200. But a bad group at 100 would definitely be worse at 200. I’ll try find a spot where I can sit back further but if not 100 will have to do for now.

Cheers

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Greetings,
I see that Nelson NZDA has a 200 metre range.
Grandpamac.