OCW Test help

[JTH]

I've been working on a load for my 300 PRC with the Badlands 195 grain and settled on 80.7 grains of N570. Seated at 3.602 it's been pretty consistent, and ES always relatively low (less than 25, today the 3 shot average ES was 14.6). For reference, here's a group at 300 yards :

Last week I took it out to 600 yards. Conditions weren't perfect, wind 8-16mph, a little gusty and quartering from different angles. Printed a group that was 4.5" or so, but it was fairly vertical. The vertical got me thinking maybe I should do an Optimal Charge Weight test. Loaded some up this morning, and here's what it looked like at 100 yards: (ignore the ant on the target to the right of 81.1)

For those who have experience with the OCW method, would you do more testing in the 81.1 to 81.3 range, or does the ES (data from LabRadar) rule that out? It was very humid this morning and 76 degrees, I've had N570 get a little inconsistent when temps get near 80 degrees, so the ES could be temp related.

 

[Doom2]

Not really familiar with the PRC but looking at your test I didn't like 81.1 at all until I picked up the ant!. You have similar POI on 81.1, 81.3 and 81.5 so somewhere in there might work. Because the POI is similar for 80.7 I might look back in the 80.3 to 80.7 range also.

I wouldn't put much weight in your ES numbers. 3 shots really provide no certainty of the actual comparison between loads. Now when you capture the 100 fps it might mean something but a 12 vs a 25 is meaningless.

 

[DUCKMAN11]

I wouldn't stray far from 81-81.4 if it were me. Your ES of 46 over 3 shots is pretty high and will start showing itself past 500yds. What dies are you using? How much neck tension are you running?

 

[L.Sherm]

Why didn't you just do a OCW test at 600?
Color your bullets and shoot them like a ladder test at the same P.O.I.

 

[L.Sherm]

A simple thing like nk.tension may bring the vertical in. I would test .003-.005 with the load you used in the pic.
It can also really help your E.S #

 

[DUCKMAN11]

A simple thing like nk.tension may bring the vertical in. I would test .003-.005 with the load you used in the pic.
It can also really help your E.S #

Kinda where I was leaning

Might need to turn the necks also if it's never been done

 

[Doom2]

Running a seating depth test on 80.7 would definitely be woth a try. Might also try it with 81.3.

 

[ShtrRdy]

I'm actually kind of surprised there was much of a group difference when step size was 0.2 grain on a 80+ grain load.

 

[med358-boise]

On a base charge in the 80s, I would be using a .6 increment. But set that aside, I think your answer is 81.3. The POI is very consistent between 81.1 thru 81.5, so the answer is the mid point 81.3.

I think people get way too worked up over extreme spread. Take your ES of 25 for 81.1 and call it 26; therefore your maximum likley variance is 13 fps. 13 fps on a base of 2900 equates to a change in drop of 2.4 inches at 1000 yards for the bullet. If your distance ranging is off by 4 yards you have a greater drop variance.

 

[JTH]

Thanks for the replies.

All of my brass is full length sized, annealed and necks have been turned. Neck tension is 0.003, and I use a Lee FCD after seating bullets. Seating depth test was performed from 0.020 off to 0.100 off in 0.010 increments, 0.050 off was the best.

I'm using the Micron dies from Bullet Central.

I'll head back to the 600 yard range with some loaded at 81.3 and see what that produces.

 

[Jeffpatton00]

Thanks for the replies.

All of my brass is full length sized, annealed and necks have been turned. Neck tension is 0.003, and I use a Lee FCD after seating bullets. Seating depth test was performed from 0.020 off to 0.100 off in 0.010 increments, 0.050 off was the best.

I'm using the Micron dies from Bullet Central.

I'll head back to the 600 yard range with some loaded at 81.3 and see what that produces.

This is very interesting, let us know how that works out, will you? And I'm tagged in now so if you'll add your results to this string, we'll all see them.

 

[KsKevin]

I'd start doing seating depth testing at 81.3

 

[skipglo]

I've seen bullets with ES in single digits shoot 2" groups at 100 and double digits like yours punching ragged single holes....so at what point do you say to Yourself..." SELF....WHAT YOU WANNA GO MESSING WITH A LOAD LIKE THIS ONE FO"?

 

[JTH]

Just got back from the range. Here's the results:

The 80.7 grain load is normally very stable, it was a little high on ES this morning at 34. Maybe the vertical results the last time out were wind related, it was 8-16mph and quartering to me. Still not as tight as I'm hoping to achieve.

The 81.3grain load had an ES of 48.5 and SD of 20 (one round was 2988 fps, most of the rest were around 3020 and one topped out at 3036 fps. I'm thinking the ES may be temp related, I'm using N570 and I've seen it get a little inconsistent when temps get near 80, it was 75 and humid/drizzling this morning. Wind was occasionally gusting 5-7mph, mostly pretty calm. The horizontal is likely wind drift not accounted for.

Would you try to tweak seating depth on 81.3 or go another direction?

Splitting hairs here, but would like to get this dialed in like my 7Max. Shooting 151 PVA Cayuga's, here's this mornings results: