(From Author/inventor of OCW)
You are in fact able to understand that OCW is (basically) three ladders... I just fire the shots round robin to factor out error potential. I've had a couple of statisticians validate the process, and they agree that the round robin firing sequence has definite and very significant advantages. And since it's as easy to fire round robin as to fire three consecutive ladders, I say do it round robin--it can't do anything but make the results more valid.
I also shoot each powder charge at its own bullseye, so as to better note POI shift with regard to the point of aim, which I believe is important.
I understand also your point that the top end of the window is often more accurate than the center, this is often (from what I've seen) because the ES is lower with the higher density charge.
I would still hope that folks will consider the existence of the scatter node which I talk about on my site. Three consecutive ladder tests would generally identify this scatter node, and of course OCW does also.
I have further found that if you add about 1.5% to the powder charge at the scatter node, you're right in the sweet spot (or what I call the OCW, for optimal charge weight).
Loading at the top of the window for competition, or for cold weather use in a hunting rifle, is always an option. Load at the bottom of the window when you're shooting a recipe in hot weather that you developed during cooler temps.
I realize you guys put your loads together often on match day, and that you would never compete with a load you hadn't tested at the match day temperature--I understand that.
But OCW can still be used to effectively identify a stable load for match day; even from the highest dollar BR rifles (provided you ran the OCW test in the same weather conditions you'd be shooting the match in).
This one won't appear in any reloading manuals because they are master and man with the bullet companies and want you to use as many components as possible:- Find a load that gives the right amount of pressure and velocity but don't worry about accuracy at this stage. Next seat the bullet well out and measure the distance between the cartridge case neck and the spot where the ogive touches the rifling, usually this distance is 5/16" in most calibers. Load 15 rounds with your preferred powder charge and load in 5 3 shot batches. Start with an overall length of loaded round that just kisses the rifling and work back in 5 equal increments each of which will be about 1/16". Fire the 5 3 shot batches. Measure each of your groups and if you have a well bedded rifle and you can shoot consistently off a bench rest. A graph of your fired groups will look like an ice cream cone, with the pointy end facing either towards the rifling lands or away from them. With the accuracy direction established it's easy to fine tune as moving seating depth towards the ice cream will make groups bigger and towards the point of the cone smaller. Most tuning methods work but this one is very reliable.
I’m no expert but here is what has been my priority.
- Seating depth
- Finding a proper bullet weight for your twist construction type for your shooting application
- Finding the proper powder based on manuals and a little on the internet.
- Run the ladder with powder charge to find the best points for that combo.
- Try a few different primers if I’m really hurting to squeeze the most out of it.
Finding the proper seating depth, or at least on the rifle seems to relatively like, is fairly easy and something I do first. After that you really have to look at what bullet weights your rifle can handle. If you have a slow twist there is no point in running a heavy bullet. Then when you know the weight range you need to pick the bullet type that works best for the shot. If you are hunting varmints then you want something explosive. If its deer then something with good expansion and weight retention. If it is target work then something that is a match bullet. Getting the proper powder from here is important. If you don't have a powder than burns at the right rate you will see problems. A lot of manuals have accuracy loads and there is quite a bit of info online telling of groups people have seen with certain combos. I take what looks like it will be the best powder for the bullet and start there at the minimum charge and work up by .3gr at a time. Once I find the one or two best shooting loads I work up and down from them by .1gr and see what shoots best. If none of the initial loads spaced at .3gr show good results I switch powders instead of moving to .1 changes. Once I have a load that seems real good and has proven itself a bit I will try changing primers and see if that has any help.
Step one. Always... Ask what powders other folks are using successfully in your particular case. Pick the most popular.
Go up and down in burn rate from there and shoot a 5 shot group with each powder to find out which one and what burn rate the gun seems to like the best. Many times, you'll eliminate a lot of guess work just by looking at powders alone. In my experience, especially in finicky guns, they tend to like one powder the best.
From there, it's the same game we all play with our loads. Keep tweaking till you are happy, and don't be surprised for that to be never.
Bullets are chosen by the barrel, or vice versa if you did your homework. Where there's a lot of choices of bullet, tend toward the heavy side of what's available to work in that twist and you'll see your best overall performance at close and longer range.
Primers I'd put way down the list. In most guns, you really can just shoot what'ca got as long as you're not picking between mags and stds. Then it gets sticky.
I'd also place good casework somewhere just following the powder or before. Make sure that you can get your cases the way you want with the least number of steps possible and you'll be happiest there. Too many casework operations invariably lead to headaches.
When in doubt, always go back and read the Lyman or Lee reloading manuals sections on basics of reloading and see what it is you got away from doing.
Depending on the scope/power and distance, you may benefit from a "cross" instead of a dot. I find the long cross allows me to ensure I have not tilted the rifle.
I simply log each shot on a target at the bench....the cluster gets very obvious...sometimes more than one.
1% of case volume for the ladder, can then be fine tuned once you find the cluster/s.
The object is to fine a node or two ( where group/clusters form) and then fine tune from there. 200 yds is better than 100...easier to see clusters..... part of the process is to foul the bbl, and then shoot the increments in the same time interval (same bbl condition/heat)
Pick the bullet you want to shoot after you make sure that the twist rate in your rifle will handle the bullet
Pick a powder that is known to work in that caliber by doing research or asking questions.
Pick a primer that is known to be accurate.
Pick a load on the low end of the powder charge weight and follow the directions by Lynn in this link.
Once you have the best load for that powder type and bullet change one variable at a time if that load does not work to your satisfaction.
One recommendation before I start load work up is I always remove the scope and bases from the rifle and reinstall with locktite and the correct torque specs.
Check the trigger to make sure it is not too stiff or creepy. Must be real smooth to get good groups.
The ladder test works great if done correctly. I have a 300 win mag hunting rifle that I have shot several groups in the .318 to .360 with one group at .242 using this ladder technique I learned from Lynn.
A few details. Be sure you are using a lot of cases that have all been fired an equal number of times.
Some small steps can add time to your reloading, such cleaning primer pockets or trimming case length or measuring charges on a scale, but they tend to give you confidence in your handloads. And they will add uniformity, regardless of whether any one step will make a very significant change.
When starting from scratch with a new cartridge, I go back in my notebooks to a rifle somewhat similar to my new rifle. I see what powders did the best for me. The advantage may not carry over with a different cartridge, but they give you an idea of where you can start. It is better than guessing blind.
The powder that gave my best loads in my .243 with light bullets has also done well in my new 22-250.
Find your bullet first. I believe that barrels and bullets are the primary determinants of an accurate load. Since it is much easier and cheaper to change bullets than barrels, we let the rifle choose the bullet. I choose my favorite bullet and hope the rifle likes it. If it doesn't, I'll switch to my alternate bullet and start again.
Pick a powder. If you look at several handloading manuals, you will notice that there are usually a couple of powders that stand out from the others in a particular bullet weight. You can also use recommendations from other handloaders on sites such as this, but don't be shy about taking internet advice with a grain of salt. There are a lot of people on the internet who are absolute idiots, and many actually know less than you. That won't keep them from giving you advice. For the most part, you can rely on companies that have invested a lot of time and money testing many combinations of components for a load. If a bullet manufacturer states that two certain powders were the most accurate in their testing, you can usually take their word for it, at least with the same components they used for their testing. If your bullet doesn't like that powder, try your alternate powder and start over.
Seat bullets out as far as you can, initially. For a hunting rifle, I usually seat my bullets as far out as the magazine will allow. Once I have found my load, I can incrementally seat the bullet a little deeper to fine tune the load.
Use the ladder method to work up your load and find the sweet spot.
Changing primers is the very last thing I try if I'm not happy with a load. I usually use Federal Match primers. They are very consistent. Consistency and accuracy are very closely related.
Practice, practice, practice.