Need help interpreting OCW test results

[Bob 964]

This is the result of an OCW test of the Hornady 178 Amax. The rifle is a Savage 110FP w/1:10 twist. The powder is Varget, with test loads ranging from 43.0 gr. to 45.1 gr., in increments of 0.3 gr.

When I look at these results, I see what appears to be an accuracy node from 43.0 to 43.6, followed by a very tight group at 43.9, followed by another accuracy node from 44.2 to 44.8, followed by another tight group at 45.1. The node from 43.0 to 43.6 appears to be the better of the 2, with 43.3 being the optimal charge weight.

Does anyone see this differently? I would appreciate any and all comments.

 

[bigedp51]

Eric Cortina of Lapua Team USA answers your OCW test results, click on link below.

Long range load development at 100 yards.

 

[rduckwor]

I agree with your assessment and possibly see another node beginning just below the 45.1 group. Any pressure signs at 45.1? I might take the 44.8 and run another series using 0.2 grain imcrements while carefully checking for any pressure signs.

Good Luck,

 

[bigedp51]

If you read the link I provided, Eric wants to see three groups vertically in the same place in relation to the bull's eye. The velocity of these three groups should vary very little. Eric also shoots loads in 1/2 increment to get a better idea of where the vertical line flattens out. Post your photo at the link provided and see what Eric Cortina of Lapua Team USA has to say.

 

[Dan Newberry]

I've been shooting bugholes, literally, with 43.1 grains of Varget and 178 AMAX's, in Winchester brass. I use CCI 200's or BR-2's.

I would not go above 44 grains, as I strongly believe at some point down the road you could end up puking a primer, and in the case of the old 110FP you'd potentially weld your ejector pin into the bolt face. In my case (voice of experience if you haven't figured it out by now) I had to replace the bolt head on my 110FP with a new style, dremel out the key inside the bolt tube (easy to do), and install a later model firing pin and bolt retaining pin. This was about a 60 dollar fix, thanks to Brownell's being fair with their parts pricing. But it still didn't have to happen...

I was simply "driving it like I stole it" using Varget and heavy bullets.

I'm getting better accuracy now, and better case life, with a lot more piece of mind running the 43.1 grain load.

If I were you, I would test 5 shot groups of 42.9, 43.1, and 43.3 and see which one works best. Shoot those round robin as well... and you'll find something that rules.

I'm running an OAL of 2.850", so it mag feeds very smoothly (from the Savage, that is).

Dan

 

[rduckwor]

Dan: Will that load get you out to 1K?

Thanks,

RMD

 

[Dan Newberry]

Easily... I'm actually getting just over 2600 fps from both of my 26" barreled rifles.

We've shot the 178's to 1200 with less MV than you'd think necessary to have them make the trip accurately--but they do. I don't know how these things behave in the transonic region, I've not worked with them enough. They're fantastic bullets.

Dan

 

[Bob 964]

If I were you, I would test 5 shot groups of 42.9, 43.1, and 43.3 and see which one works best. Shoot those round robin as well... and you'll find something that rules.Dan

That makes sense, Dan. I was thinking of something substantially similar to that.

 

[rduckwor]

Easily... I'm actually getting just over 2600 fps from both of my 26" barreled rifles.

We've shot the 178's to 1200 with less MV than you'd think necessary to have them make the trip accurately--but they do. I don't know how these things behave in the transonic region, I've not worked with them enough. They're fantastic bullets.

Dan

Excellent. Thanks,

 

[savageshooter86]

44.5 sure does look almost exact same POI as the charge above and below? I would look at that again possibly