Load Testing

[ndbwhunter]

Been doing a lot of load testing on my 300WM. Finally found two loads that shoot well, but can't decide what to do next. Loaded from 73.5 up to 77.5 grains of RL26.

First charge - 73.5 grains of RL26 pushing a 180 barnes TTSX a hair over 2800fps. 0.335MOA (all touching with 2 in the same hole)

Second charge - 77.5 grains of RL26 (same bullet) at roughly 3100fps. 0.65MOA (clover leaf)

I would love the 77.5 to have been the best based on the velocity, but clearly that wasn't the case. Either group is excellent for the purposes of hunting, but I plan to test a few more charges near the 77.5 load and switch up the primers to see if I can tighten that group.

Should I try working up from 77 in 0.2 grain increments up to 78?

Everything in between the two charges above started to open up before finally tightening up again as I got closer to 77.5.

What would you guys do? Leave it, or keep playing?

 

[nhyrum]

What were your increments before? Half a grain? Load work is less about physical group size and more about finding a velocity plateau across a few charge weights. A few key things are your extreme spread and standard deviation. When those are both low and you have a window where you could either increase or decrease the charge we've get a negligible velocity change, your shot to shot velocity will be more consistent leading to less vertical stringing at range and minor charge differences won't have as much an effect, because as much as we all try, no load will be 100% identical as another in terms of energy.

The way I like to go about it is an ocw(optimal charge weight) test. I do a minimum of 5 shot groups, round robin style. You're looking for two things, the velocity plateau I mentioned earlier, and you'll also watch the average point of impact shift (poi). Generally, the velocity plateau and no poi shift will happen together.

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[Rich M]

Run em both!

3100 fps, .65" MOA - I'd be done. of course you can probably tighten it up some.

 

[CanyonHunter]

I would be done at 77.5, good speed and accuracy. Unless you want a little more out of it, i think the extra tinkering isn't needed.

 

[JakeSCH]

Lol the day I stop playing with a load is a day I am shooting a different rifle / caliber.

On the flip side, its very important to identify your goals of the load upfront. Do you want to shoot 300y, 600y or 1000y? How far do you plan on using this on game? When using mono's you want as much impact velocity as you can get for best terminal performances. Those will drive your solution.

 

[Rob5589]

Either. If shooting longer ranges, choose the one with the lower sd.

 

[eaglemountainman]

You could play with the seating depth .002 at a time to see what kind of a jump to the lands each load likes. I would start .015 off and work from there.

 

[T28w]

I’d shoot a five to 10 round group and see what happens

 

[Travis Bertrand]

Why mess with a good thing? I say run it. I stopped chasing loads a few years ago. If it’s close to .5 moa im content. Especially for a field rifle. Heck my comp gun same thing!!


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[ndbwhunter]

I think I'm going to run the 77.5 and try two different primers to see if that does anything.

 

[rootacres]

I would run 10 of the 77.5 over the chrono to make sure your SD's are acceptable (if you haven't done that already). If all checks out don't mess with the powder drop anymore. From there a slight change in seating depth can really tighten up a group. Maybe ladder .035" - .050" - .070" - .090" off the lands and see what happens.

That said I think most of us have taken a rifle out on a hunt that barley meets that sub MOA benchmark many look for. On my last two hunts both the rifles achieved repeatable 3/4 MOA accuracy. My latest re-barreled build is a legit 1/2 MOA rifle. Luckily the load development only took 1 trip to the range.

 

[EdP]

You obviously have a completely acceptable load at 77.5 under your test conditions. nhyrum makes some great points that would help ensure that load works just as well under a variety of conditions. If you like playing with it I'd work it as he recommended. If you have better things to do I'd have no qualms going with it as is. I don't think any animal is going to know the difference.

 

[Mike D Texas]

I would run a seating depth test at 77.5 (assuming you’ve already checked that load for good SD/ES). If the SD/ES looks good you’ll likely tighten that up a bit.

There’s no sense to have a 300WM to run at 30.06 velocities. And the extra velocity will help with expansion on the mono bullets.


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[ndbwhunter]

I would run a seating depth test at 77.5 (assuming you’ve already checked that load for good SD/ES). If the SD/ES looks good you’ll likely tighten that up a bit.

There’s no sense to have a 300WM to run at 30.06 velocities. And the extra velocity will help with expansion on the mono bullets.


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This is exactly what I ended up doing. Messed with seating depth on the 77.5 grain load and found the sweet spot. Ran a 10 round set and ended up with an SD of 9.1 and ES of 27.