6.5 PRC load question

Iamnotagolem

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I'm trying to work up a load for the 140gr Nosler Ballistic Tip/Accubond in my 6.5 PRC. I group them together because my thought is that they are the same weight and have the same BC, so, in theory, the same load should work for both. Obviously I will confirm, but I'm working up the one that is $10/box less first. Happy to hear any thought on that whole thing.

I'm shooting a Seekins Havak PH1 with a 24" barrel and a 1:8 twist. It had 152 rounds down it when I started this test and it appears to be broken in. I took my load data from the Hornady book, which was much higher than the Hodgdon data for some reason, but so be it. I loaded up 10 rounds at 0.2 grain increments and chrono'd them with a Magnetospeed Sporter. I wasn't able to get to an actual range because my luck runs less than awesome. Today was the first time I could get to the range in the past 11 months due to a surgery, moving to a new state, and a pandemic. Turns out today was a holiday, so they closed the range. Best I could do was shoot at a rock 250 yards away in the National Forest.

There was a very clear and very large velocity node between 57.9gr and 58.5gr. There may also be one at the 59.1gr and up level, but I didn't go high enough to find out since 59 he was the book max, which is why I stopped at 59.3.

My first question is, should I load up some more and go higher to see if there is a higher velocity node? I don't believe there were any high pressure signs on the brass, but I've attached a pic so the more experienced hand loaders can tell me. The lowest charge is on the left and moves to the highest on the right. If there is another node above 59gr, is the extra 50fps worth the wear on the brass, or is ~3,030 fps a decent speed for a 140gr 6.5 PRC?

Pretty sure my next step is to shoot groups at the velocity node(s). If it's not awesome, I'll adjust my seating depths and retest. So my next question is what interval should those changes be? 0.010"?

Thanks for any wisdom you all can provide!
 

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It sounds like you are on the right track. If your current load proves to be accurate at 3,030 ft/sec then I wouldn't bother looking for a higher node. More pressure just shortens brass life, sometimes considerably.

Years ago I compared the BT & Accubonds of the same weight in a .308Win rifle. They did shoot nearly the same groups but point of impact was different at distance.
 
I agree with Varmint, if the 3,030 shoots well I would run with it. H1000 is a great powder for this round and that speed is reasonable for the high BC bullets. My PRC likes 58.7 gr of H1000 with the 140 accubond. I'm getting around 3,060 with that loading. I probably could have pushed for a higher node, but I'll trade the extra 50-100 FPS for barrel and brass life.

As far as seating depth, I might go by 0.005", but its likely splitting hairs. Mine shot well enough at 2.880" (seating depth for the Nosler BT in the Hodgdon data) I didn't bother. In my gun that is about 0.060" off the lands.
 
Thanks guys. I'll stick with the node I've found and play with the seating depth until I'm happy. I appreciate the couple extra sets of eyes on this as it's a new method of load development for me and I want to make sure I'm doing it right.
 
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