Question about testing accuracy for load development

Redlich

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Hello CGN'ers!

I know that the traditional method to test which load is the most accurate is the good old fashioned way of finding a 100m or 200m range, setting up the sand bags or bench rest rig, and measuring group size.

I've also read elsewhere, however, that some shooters including competitive ones simply chrony their loads and choose the one with the smallest standard deviation in velocity.

I understand that during firing the muzzle will move based on the harmonics of the barrel, and that the purpose of perfecting a load for a specific rifle is to ensure that the muzzle will be in the most predictable and consistent orientation when the bullet actually exits, based on when the bullet exits between "waves" as it were.

It makes sense to me that just measuring velocity and getting the most consistent load might work, because at the very least you're reducing vertical stringing, and hopefully it will also ensure that the muzzle is in the same position for each bullet exit because the bullet takes the same amount of time to travel through the barrel and accelerates in the same way each time. Consistent velocity also indicates consistent burning characteristics of the powder in the chamber from shot to shot.

But... does it actually work? Can you choose a load based on the most consistent velocity with the smallest standard deviation, and trust that it will truly give the smallest groups on paper? I'm asking for two reasons. First, I think for me it would be easier to just go with chrony measurements, given range availability etc, and second I don't perfectly trust my ability to set up a rifle to shoot consistently small enough groups to see differences from load to load yet. That would take practice I suppose, but it seems to me that there is less chance for error in using a good chrony than making sure that human error is removed from the aiming factors to test loads.

Thanks for any input!
Red
 
The idea is that your desired end result is to put the smallest groups on paper, so that is the most direct observation you can use. The chrony is a useful tool, but you have to account that its data is not necessarily perfect either. One thing which you may find useful is the "ladder test", mysticplayer's article about it is linked below.

As for trusting your ability to shoot that way, focus a bit of attention into that and the confidence will come soon. Read an article about the fundamentals of marksmanship, spend some time in dry-fire practice watching what happens in your follow-through, shoot lots of .22 to hone that technique and see errors by the way your groups pattern, and you will find that most of the elements of shooting accurately from a rest will come naturally. Your rifle is only as good as you are, so making it shoot .3 MOA when you can do .5 is not going to help as much as focusing your effort into practice. It's all relative, there are a lot of little things I could be doing to marginally improve accuracy, but I have my gun shooting better than I can right now and those little things can wait until I catch up. I am not 100% confident in any of this myself either, and I have only been shooting accurate rifles for less than a year. But I am realizing that the fun of it is in that challenge, of approaching the task with uncertainty and getting results from it. That's what i like about this kind of shooting, the sky's the limit.

Here a few relevant articles I have read recently. Have fun!

www. longrangehunting.com/articles/reloading-load-tuning-1.php
www. snipercountry.com/mark1.htm
www. 6mmbr.com/TacticalFroggyA1.html
 
You cannot work up a load from just a chrony. If you have access to a 600yd range, do a ladder test and in 20-30 rounds you'll be able to see 2 "nodes" of accuracy ON PAPER, there the biggest part is done, now you can narrow it down between those 2. If you are looking for the most velocity and accuracy, you'll take the higher node, if your a little more conservative you may take a little less velocity. Once you get into your node you can then start trying to reduce your ES/SD numbers with a chrony.

Just because you get a good group at 100yd doesn't mean diddly squat at 600+. If you plan to shoot long range, do long range load development, if you do short range BR, do short range load development.
 
You cannot work up a load from just a chrony. If you have access to a 600yd range, do a ladder test and in 20-30 rounds you'll be able to see 2 "nodes" of accuracy ON PAPER, there the biggest part is done, now you can narrow it down between those 2. If you are looking for the most velocity and accuracy, you'll take the higher node, if your a little more conservative you may take a little less velocity. Once you get into your node you can then start trying to reduce your ES/SD numbers with a chrony.

Just because you get a good group at 100yd doesn't mean diddly squat at 600+. If you plan to shoot long range, do long range load development, if you do short range BR, do short range load development.
X2
I like the chrony for knowing my muzzle velocity AFTER I have worked up a load
 
My opinion is that the short answer is No. It will not work. It does depend on the distance you plant to shoot, but absolutely for the short ranges (100-200 meters), velocity variation is not a big factor in causing inaccuracy. But, yes at 1000 meters it is an issue, and one of the things you have to control.

The proper procedure in my view is to find your barrel sweet spots first, and then fine tune that with seating depth, primers, powder, for accuracy, and potentially very last for minimum velocity SD.

If you want to take the fast track method to finding a good load, I would try and find someone who at least has the same cartridge, same barrel length, and weight, and has done the full ladder testing to establish sweet spots, by velocity. Then use your chronograph to duplicate those velocities in your gun. Quite likely your sweet spots will be at a very similar velocity.
 
Mid range ammo (600 yards) has to be developed using groups at least at 300 yards. 100 yard groups don't translate to down range performance. Chrony does not tell much except powders that don't work - Sd over 50 fps.
 
Just a little quote by Tony Boyer(one of the top shooters in the benchrest circle) from the Precision Shooting Annual(1996). He says "the best loads often have a wide velocity variation". Just something to consider.
 
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