OCW test, did I blow it?

[diego-ted]

I loaded 4 of each weight instead of 3? How should I interprete this? Or do I need to a do over?

308 Savage fTR, Varget powder, FGMM 210 primer, Hornady 178 BTHP.
thx Ted

 

[Dan Newberry]

That's well over max.... the dispersion you're seeing could simply be high pressure (even though you may not see it on the case rims) spreading things out.

Look for the OCW between 43.8 and 44.3 grains if you're using Winchester brass.

 

[rdinak]

45.4 looks good to me.

 

[Dan Newberry]

45.4... there very well could be a node there, but I'm wondering if that load will continue to work well... it's pretty warm.

But I agree, if you're going to choose something here, the 45.4 would be a possibly good choice.

Dan

 

[diego-ted]

Sorry, Lapua brass, it was pretty warm out today about 73*. Dan, where would you take the testing from here?

 

[damoncali]

You need to shoot more. There's only so much information in a single group. It's not uncommon to find a good load at an unacceptable pressure. Them's the breaks.

 

[mtang45]

Any pressure signs at 45.4? Severely flattened primer, cratered primer around the firing pin strike, hard bolt lift on extraction? If not then your probably good to experiment a little higher. If you are seeing any of the above then back off and do your testing a little further back down the ladder.

 

[RyeDaddy]

Dan knows the most on the subject.

You are over pressure at 45.4 in Lapua brass, although that's where your node is. When it gets hotter outside you'll see it. I start seeing pressure signs around 45.7 in hot weather with 168 hybrids in Lapua brass with Varget. You can run that load if you want, but I wouldn't. The brass will probably wear out pretty quick.

Anyway, most of the info out there about 178's points to 44.0-ish working well. Not coincidentally that's 3% EXACTLY below the 45.4 grain load on your target, which is where Dan's method would predict it to be. I'd try that. Maybe go 43.6, 44.0, 44.4 and see how that looks. Bet it's good, the OCW method has worked well for many people.

Nothing wrong with 4 or 5 shot groups if you like, they're your components to burn.

 

[M1Amen]

I would investigate the 45.4 load. That one looks like a node.

 

[melloyello]

It's funny to me that people immediately jump to the tightest group as the load to go with on an OCW test. With so much info out there on how to perform and read an OCW how do so many people make the mistake?
You are probably going to find a good node somewhere between 43.5 and 44.5gr Varget. Did you happen to shoot a 44.2 gr load? How close was the POI to 44.4 and 44.6? If they all had the same POI then that is where I would start.

 

[Dan Newberry]

In Lapua brass, yes... look in the 44 grain area (plus or minus .3 grains).

There would be another node at about 43.1 grains, in all likelihood.

When you push Varget that hard, odd and unpleasant things happen when you least expect it. I'd tone it down a grain... or two. Your brass and your rifle will thank you, and accuracy will still be great, and velocity will be 2600 or so from a 24" barrel.

Dan

 

[melloyello]

Ryedaddy, I don't know where your post went to that you quoted me in but this was it:
"It's funny to me that someone would imply that the smallest group on the target that shares POI with the 2 increments preceding it(and likely the one or two following) that are seen closing up tighter was not a good OCW load. Hmmmm... Is that what you're saying here?"

That is exactly what I am saying here. 45.4gr is not an OCW. You are correct, 45.6gr would have probably had the same POI. I see a lot of people gravitate to the most accurate load and they don't pay attention to other things. Yes, it may have been a node but it's not the OCW. It's too much powder. When picking the right node we have to look for more than one thing. We can't just look at just POI or just accuracy. Yes, they are important but abusing our brass at max or over max recommended loads has to be considered also. Knowing that the barrel on this thing is 30" I would assume there is no need to exceed 44.5gr of varget for any reason to achieve good velocity. In fact it's probably going to be less than or pretty close to 44gr.

 

[RyeDaddy]

I deleted it right after I posted it because I realized it was argumentative and you were right.

I see what you're saying. Good node vs OCW, and anything above 45 with that combo isn't going to work year round and anything that qualifies as "THE" load needs to be. We seem to agree the OP would do well around 44 grains.