Load testing protocol

[ckaz34]

I’m new to reloading and tried four different charges today. Five rounds at each charge. I know barrel temperature can effect accuracy, so I’d wait five minutes between each group. But I have no idea if this influenced the groups for each charge. What are some protocols you guys use?

 

[jfk69]

Read this. Follow it. Don’t waste components.

Thread 'Painless load development (mine)'

Oct 25, 2021

I have had multiple people ask me to lay out how I do load development being that what I do is different. Since Shaen @Shooter71 just rebarreled a Tikka 595 in 6XC I thought it would be easy to show how I do it. It’s a Master Sporter with a T3 lite profiled 20” barrel- keep in mind it is a T3 LITE barrel. So by conventional “wisdom” it should be more picky and less accurate than a heavy barrel. His work is shoddy (), but I bet I can overcome it.

The rifle-


First was @Unknown Munitions factory load with 105gr Berger Hybrids. 5 rounds to zero, 5 for a...

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• Forum: Reloading

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[Hschweers]

I’m new to reloading and tried four different charges today. Five rounds at each charge. I know barrel temperature can effect accuracy, so I’d wait five minutes between each group. But I have no idea if this influenced the groups for each charge. What are some protocols you guys use?

Are you shooting a magnum with a pencil barrel? If not, I don’t think heat would massively affect your groups over 20 rounds. The data you have is probably valid.

The painless load development tagged above is the way. However, I still don’t do it that simply because I’m only a couple years, few hundred rounds in, and pressure still scares me.

My process in regards to your ladder/pressure/accuracy.
1) find book min, book max. Load (3) ea at .5gr increments for a pressure and start of accuracy ladder. I personally don’t start min, cause it’s always way too low, but usually start 2 grains below max. This gives me (5) 3-shot groups (say 44.0gr is max. (3) ea at 42.0, 42.5, 43.0, 43.5, 44.0) working up to max for 15 total rounds, and makes me feel way more comfortable with pressure. 5 is too many for this initial purpose imo. I also load all of these at .010 jump for that bullet (or kissing the lands). Every bullet is different. Get a tool to measure this.

2) I now have either found pressure and that’s my max, or book max is my max (assuming I’ve achieved the velocity I want - identify this goal before you start). In the example above say i never found pressure but 44.0gr gave me the velocity I want (and better yet, without pressure). I then look at what that 3 shot group did. Was it under an inch? Or whatever accuracy standard you’re using. If yes, load 10 and shoot a 10 shot group the exact same way. Hopefully you’re done. If no, load a ladder of 3-shot groups at .050, .100, and .200 jump. Shoot those and evaluate. Typically you have now found something solid. You can fine tune .1gr increments or .005” jump changes, but I agree with the painless method - unnecessary. If you’re still getting 2” groups after those 24 rounds, change a component. Bullet or powder.

On point 1, I often only load 1 round at 2 and 1.5 grain below book max to check for pressure. I’m really not interested in those group sizes because they’re likely too slow for me to be interested in them as a final product. I usually start 3 shot groups at 1 grain below max.

 

[Harvey_NW]

The only time heat effects accuracy is if there's stress in the grain structure of the material from improper relief, in which case it's a bad barrel and needs replaced because it's unreliable. It also takes a large sample to prove it's repeatable, if that is the case.

High shot strings do contribute to throat erosion, so I shoot 5 shot strings and usually 10 min cool time between groups to mitigate suppressor mirage as well. Otherwise basic load dev protocol is load ~.040" off the lands (most of my rifles are custom throated for a bullet weight class I want to shoot and are near that when the boat tail edge is seated to the neck/shoulder junction), and do the painless method.

 

[TaperPin]

I’m new to reloading and tried four different charges today. Five rounds at each charge. I know barrel temperature can effect accuracy, so I’d wait five minutes between each group. But I have no idea if this influenced the groups for each charge. What are some protocols you guys use?

I’m likely to set up four targets and shoot them round robin so each group gets the same amount of heat. The downside is it makes getting useful velocity information for a specific load harder. Probably just as often I’ll shoot a group and put a wet towel on the barrel for a few minutes to suck the heat out, then let it sit a few minutes to equalize any remaining temp differences from above stock line and below where the towel can’t reach.

As for determining if a particular barrel moves, simply watching each shot as the barrel heats up is usually enough. Of course that’s much easier with a spotting scope. If the first two or three shots at the beginning of the group are roughly just as spread out as shots at the end that’s much different from a gun that always seems to put the last couple to one edge of the group. The problem with 5 shot groups is they are usually not a perfect representation of what the load does, so saving targets and stacking multiple groups on top of each other works well.

When beginning reloading it’s good to remember shooting more shots will never reduce your group size. If the first two shots have already made a huge group I’ll stop shooting that load and skip to the next. Same when comparing something new to a known good load - as soon as the new load is a larger group I stop even if it’s the first two or three, because more rounds can’t make it better. The unused rounds work well enough for offhand practice.

 

[Blurry1]

only thing I might add is if you want to slow the barrel from heating up slow down. Spend time looking at the brass you just shot and compare it to the previous shot and the last group. Maybe pick up some range brass or if your at a poorly maintained range do a little clean up for 1-2 minutes before settling in for your next shot.