Thread: Testing a conventional approach to load development

Originally Posted by Micky Duck

Right so I do believe there is one other test that hasn't been done that would answer more questions than most others and allow some folk to rest easy and be happy with what they are using. RUMPY has said it well above,others along same lines. The how far away was last deer poll was eye opening. Bottom line is this. Good enough is good enough. It's a personal thing how good you decide is actually enough. A deers vitals are generally considered a 8" vital area. If we halve that to try and remove some of the environmental and human factors we get 4" as ethical must be able to consistently get group size for given range....which by default tells us our own personal ethical range EG when you can't hold 4" or better you need to get closer. Your rifle n load might be good for 1" on a bench rest on bluebird day out to two hundred yards (oh the skills needed) but on steep slippery slope in howling norwester you may struggle to achieve that 4" freehand at 50 yards. So how about let's cut the crap and try one more test???? Same rifle,same shooter,same conditions and use every combination of run of the mill loads you have got access to. Cartridge doesn't really matter,the 223 is possibly cheapest beast to do this with. I may have been nice to old ladies in previous life but at hundred yards my centerfire rifles don't change enough between yards to matter at or under hundy.

What level of precision is required for hunting at conventional ranges? It's a good question - you could start a thread to discuss it and test it. I have some data to input.


It is however not the focus of this thread or line of investigation.

I did seven months ago and got banned when .... Didn't like direction it was heading.

Cool thread

This is by no means scientific but I’ve found several times that a rifle likes to shoot x weight projectile at x speed. For instance trying 3 different powders I got the ‘smallest groups’ with each powder at the same velocity.

I’ll pay more attention to getting bigger data sets like the OP and see if this trend keeps occurring or if it’s just been coincidence.

If these ‘velocity windows’ are a thing then how big are they? How many grains of powder can we vary while remaining in the ballpark.

Sorry I’m off on a tangent.

As a very average shot not a target shooter or long range hunter a basic load that does as you say is how I load.

I have non-hunting and non conventional needs for load development for several rifles. But the level of testing I need to do often isn't associated with the load itself but cleaning and shooting regimes. The below target is with black powder 38-55. I was testing how long I can shoot reasonably quickly while blow tubing before shots went outside the group. 40m, as that's the longest range I had at the pistol club, will do some slower group testing at 100 and 200m later. I had 20 shots out of 21 fall inside the group, shots 22-25 went out. So 20 shots is my upper limit before I have to clean when target shooting, assuming consecutive shots. If there is a pause in shooting fouling may harden so the regime shortens (but I also have time to clean so no issue). Shot 14 was well outside of the group this I consider a genuine flier of unknown cause, most likely a deformed cast projectile base, but I don't know.
The long and the short of this is load testing should fit intended use.

My smokeless load testing consists of a load ladder to find pressure or velocity I want, often only 1 our 2 shots per charge weight, not shooting for groups, but I shoot to the same point of aim, generally even several grains of powder difference are not detectable in terms of point of impact with any reliability at 100m. If this mixed charge weight group is massive - I'll change powder or projectile or both. Then I sight in with the charge weight that gets me the velocity I want. I actually don't believe powder weight nor seating depth influence group size to the extent I can detect so if a load doesn't shoot it's either the rifle, powder, or projectile that'll be changed. People doing a lot more testing than I can bother to do, in applying appropriate statistical tests would appear to align with my belief.
Post script note: the 1 or 2 shot velocity check often results in one powder weight apparently shooting slower than or the same as another, this is just statistical noise, I'm just looking for the velocity, or thereabouts. With sufficient numbers of shots the relationship between charge weight and velocity is directly proportional, no such thing as velocity nodes.

Note: before anyone mentions size of group = size of aim point. I'm using open sights, with a circle front sight element. Aiming at a black dot ensuring an even amount of white ring shows around the aim point is incredibly precise if the front sight element fits the aim point dot well (just a ring of white showing). This day the front sight element was slightly too small but good enough for the level of accuracy I needed to test so I didn't swap it out, I would suggest quite a bit of the group variation is shooter/sight alignment error because of this.

Originally Posted by No.3

As far as does shooter fatigue contribute to larger groups - yes. It's been proven several times over and there are several sources of fatigue that do it - eye fatigue from not blinking enough or focusing too long or optics that aren't set quite right for your eye, muscle fatigue, cumulative effects of recoil and blast, excitement and/or pressure on weird bits of the body from lying over something awkwardly all play a part as does nutrition and hydration. I can't shoot for nothing when I need to take a piss for one!

Can you provide some sources that quantify this or that provide evidence that shooter fatigue is a significant issue for shooting 5rd groups?

Thanks @gimp for this post. Coincidentally I used the same approach in the weekend for 7mm rem mag load development. I have used it for my 270win before and found it to be very beneficial.

I was a bit frustrated on the weekend during the first stage of the process as the labradar wasn't liking the AA batteries I brought (hence only three readings for the first two strings), and the testing of different charge weights didn't yield the best results with regards to standard deviation and spread, although they were mostly all grouping well at 100m. I have since gone through a process of elimination and found that one of the nuts on my press was ever so slightly loose which may have been hampering a constant neck sizing and tension.

Nonetheless I will test with five shot strings of 70.3, 70.5 and 70.7 charge weights on Sunday and see if I can bring the numbers down a bit while maintaining my average target velocity of 2900fps or more. In the past I have managed to get standard dev of between 5-10fps with 10 shot strings when loading other cartridges so fingers crossed.

In saying that, the velocities and the spread it is producing currently would only make roughly two inches of possible difference in drop between the highest and lowest velocities at 600yards according to my ballistic calculator. The benefits of higher velocities eh? This 2 inch difference is not necessarily excessive for my hunting applications when considering the size of the 'kill box' on the target species. Hopefully refining the load and testing those subsequent strings will tighten the spread and reduce the std dev giving me a piece of mind about making ethical shots at range.

Originally Posted by gimp

4x 5rd groups actually.


Barrel cooled between 5rd groups (even though it doesn't actually matter), fired each load alternately to minimise any differences in fouling etc. Fired 10rd of each then went and did other stuff (helping others sort guns) for a couple of hours then fired the last 10 of each. Wind very low and consistent, <1ms 12 o'clock. Temperature consistent at 12 degrees C through the day (kestrel). Parallax dialled out.

Shooting high numbers of shots through other rifles with different loads clearly demonstrates differences in precision, e.g. .223 with handloads 0.9moa group for 20, 1.5moa for 20 with factory "match" ammunition.


How do you propose to quantify a valid understanding of the real precision capability of a system?

By the number of deer in the freezer with the least amount of bullets used.Thats all that matters to a hunter,not a compitition shooter.

Originally Posted by Trout

By the number of deer in the freezer with the least amount of bullets used.Thats all that matters to a hunter,not a compitition shooter.

Yeah both of mine are full. Good.

Originally Posted by STC

do I get this right?

it took you 40 shots to prove that you can do load development with less than 5x3 shots?

ohh the iriony!

My initial thoughts too, but good thread none the less.

I'm about to start developing a load for my 16" 308, and for me personally... I will do it as @gimp first did. Something along the lines of 5x3 shot groups, choose the group that looks the best by all accounts (soze and velocity etc) and try and replicate it a few times, and then shoot some animals. Call it job done.

I don't need a sub MOA 10 shot rifle. It's a Tikka anyway, so it already shoots 0.5 MOA without me.

Originally Posted by gimp

Can you provide some sources that quantify this or that provide evidence that shooter fatigue is a significant issue for shooting 5rd groups?

Short answer for 5 round groups - no no evidence.

Long answer, training in mil firearms handling and in target shooting would teach that good technique at deliberate shooting practice starts with a well rested shooter. Target shooting practice thinking is that you only have a short time holding the rifle on target at each shot, and that the longer you hold the more likely you are to get the wobbles or pull the shot. The more shots you make, the less likely you are to be able to hold on target as long - all other things being equal. So in a partial answer to your question, if the shooter started in a good place fatigue wise and knew what they were about, didn't take an excessive time to run the shot string or rested off the firing line between shots then I'd put forward the argument that fatigue should not be a factor for 5 round strings.

How much muscle fatigue would you expect a shooter (with good mobility) to experience shooting prone from a bipod and rear bag ?

Originally Posted by Pop Shot

It's a Tikka anyway, so it already shoots 0.5 MOA without me.

When will you grow up

Originally Posted by gimp

How much muscle fatigue would you expect a shooter (with good mobility) to experience shooting prone from a bipod and rear bag ?

Muscle fatigue is a cumulative thing I'm told - as you hold your muscles rigidly you are forcing them to consume energy to do so. As you consume energy the end result of this is waste products being formed that must be carried away and dumped from the system - obvious thing is the harder the muscles work the more energy consumed and the faster waste products are formed i.e. the faster the muscles fatigue out.

So, again - not much of a definitive answer as it would depend on the exact circumstances. Factors, how much energy consumed at what rate prior to getting behind the rifle, how stable and comfortable the position (shooting up or down over something or around something, looking directly into the blazing orb, raining into your face vs nice and comfortable level on a formed range in perfect conditions).

A lot of it is also technique - a shooter who has technique that allows them to be very relaxed and a good comfortably set up rifle that doesn't force them into a sod of a position could hold on target for a very long time. I've also seen new shooters go off and need a break in less than a minute just due to crap technique.

I'm going to compare this to a really out there task - wearing breathing apparatus. They used to run 'nominal consumption' rates of 45L of air per minute - but often found bigger framed people would come back for another can of air after less time. Smaller framed people (ladies etc) often could doubled the time. So they wanted a better average - they worked out that by putting people onto a running track in the gear and carrying loads to simulate working they could get average consumption rates to work out if the 'nominal consumption' rate was fair. After the testing the new 'nominal rate' is 60L/min.

I would suspect that the only way to arrive at a 'nominal time' would be to test a bunch of people behind a bunch of firearms and see what the result is. I know of nothing that exists like this as a 'time to not exceed' or anything like that, just what I was trained in mil shooting (admitting I never did as much as I was interested in here) and learned over the years of dabbling in the sports side.

Originally Posted by Pop Shot

My initial thoughts too, but good thread none the less.

I'm about to start developing a load for my 16" 308, and for me personally... I will do it as @gimp first did. Something along the lines of 5x3 shot groups, choose the group that looks the best by all accounts (soze and velocity etc) and try and replicate it a few times, and then shoot some animals. Call it job done.

I don't need a sub MOA 10 shot rifle. It's a Tikka anyway, so it already shoots 0.5 MOA without me.

I think you might be missing a point… gimp is indicating that the old school method that you describe above is a waste of ammo and time. By your logic why not just take your own advice and pick a projectile and powder charge that will give a suitable velocity, shoot one 5 shot group and call it done?

What gimp has done above by picking the best and worst 3 shot, and replicating with 20 shots just proves that the 3 shot group load testing is a waste of time, especially when we all no it’s going to shoot “good enough ”for what a 16” 308 should be doing