What would you load next? 6.5 PRC

AkBirder300

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Hi Guys, I shot two OCW tests today in my brand new 6.5 PRC from Pierce Engineering, one with the 143 ELDX and one with the 156 Berger. I attached pics below, would be grateful on feedback for which loads you would shoot again or how you would go about determining your next steps. I shot these groups at 100 yards, the boxes on the targets are 1/2 inch.
One interesting thing was that I noticed heavy bolt lift on the Berger load at 57 when I had my Ultra 7 threaded on, once I removed it the pressure signs disappeared and the groups tightened up. The ELDX loads were all shot suppressed.

these were all shot consecutively after completing the proof barrel break in instructions (shoot 5, clean, repeat 3x). I was wondering if maybe it needed to be cleaned again before I retest.

many input appreciated, I did shoot all the lower weights on the pics but the groups were high and off the target so didn’t record them, they were all pretty large.
 

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BoomFlop

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Where are the holes in the lower charge weights?

Personally, I’m not seeing anything special to explore. I noticed it is only approximately a 1-1.5 grain spread, which isn’t much “testing”. Still experiencing shifts in poi, did you hit pressure?

How did you choose those charge ranges?

Steve
 

AkBirder300

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Thanks Steve, the lower charges all had a POI way off the paper, average group size was about 2 inches. I started the 156EOL down at 54 grains and the 143 ELDX at 55. It was pretty strange to me how the POI dropped as the velocity increased. I did not hit pressure signs yet with either, but this was as high as I had loaded either bullet as I had heard ADG brass hits pressure earlier than Hornady and I figured I could always load higher and shoot them next time.
 

BoomFlop

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Without knowing you powder, I would suggest working up to around the max in the manual. Carefully watch for pressure signs.

I personally start my load development with seating depth tests at minimum charge weight. I start at maximum magazine length and work back. This gives me a good idea of seating depth while fire forming my brass (I use Lapua brass). Then I take best seating and work up charge in .5 grain increments till I see pressure. Looking for a group of charge weights that shot good grouping, good group shape and in the same location on target. Since I hunt mainly when it’s cold, I will load towards the highest group and load about 10 and verify that the group is repeatable. I prefer my loads to be under 1/2MOA.

Hope this helps.
Steve
 

AkBirder300

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Thanks, that does help, I had always heard to test weight increments then seating depth. That’s really interesting to learn. I’m using MagPro, which is pretty much my only locally available option from what I have found in the Hornady and Accurate manuals. I’m still about a grain or so under max so will proceed up a little higher
 

BoomFlop

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I would recommend testing in smaller increments in powder as you get closer to max.

I do seating first while fire forming my brass as my seating depth won’t charge but my powder charge will with 1x fired brass.

How many rounds have you fired? Did you start with 100 pc of new brass?
 

AkBirder300

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Ah, interesting, that’s good advice too. I’ll drop down to .2 increments for the last full grain of charge weight.
Yes I started with 1 box of Precision Match and 100 pieces of ADG from which I made the two OCW test loads. Each of them had about 33 roundswith all the different increments. I used 15 rounds of the factory ammo for breaking in the barrel and to zero the rifle at 100, then went to the ELDX loads, then to the Berger loads. There are 34 pieces of brass left that I have not loaded and fired yet.
 

BoomFlop

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I would load the following at minimum powder charge with 156 (showed some promise)

mag max length - 3 rounds
-.01 - 3 rounds
-.02 - 3 rounds
-.03 - 3 rounds
-.04 - 3 rounds
That would be 15 rounds

Then take the best seating depth from above test and load the following:


58.5 - 4 rounds (1sighter)
58.7 - 3 rounds
59.0 - 3 rounds
59.3 - 3 rounds
59.6 - 3 rounds
59.9 - 3 rounds

That will give you 34 rounds. If you don’t feel comfortable going to 59.9 or it is over max, then I would start at 58.2 or shoot another seating depth at -.05.

My opinion.
Steve
 

GrayCreed

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Personally I'd do a staterlee ladder first. It only takes 10 to 15 shots which is very conservative on powder and bullets and primers. I try to find the widest flat spot where the velocity doesn't change. Then I shoot for groups around that area. If the SD/ES is good but the groups suck I adjust the seating depth. Since I usually start at the maximum length I can seat, I only have one way to adjust for seating depth. Once the groups titen up if the SD/ES has losened up a bit I back the powder charge down .1g at a time shooting groups of 4-5. When I have both in line that's my load!
 

AkBirder300

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I am using MagPro with brand new ADG brass. Fed GM Mag primers. Ran the following loads at .5 to .3 grain increments
143 ELDX started at 55 and went up to 58.5
156 berger started at 53 and went up to 58.7
 

ATTkid

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Mag Pro ,don't know how I missed that .
Just my two cents, but here's what's working best for me. I have an off the shelf Christensen MPR. 55.7 gr. RL-26, Hornady 140 gr. ELD-M, CCI BR-2 primers, 0.02" off the lands. 5 shots in .248". 153 gr. A-Tips are loaded, but I can't shoot them yet; broke a rib last week, typical old guy stuff! Good shooting and good luck.
 

Kmccord

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I would follow what boomflop mentioned, seating depth first at lowest powder charge until you find the best three shot group, then load another three and verify it is repeatable, then work on powder testing in .5 grain increments. If you call Berger they will recommend the same. I did this for my Grandsons 7mm Rem Mag and it worked like a charm, found .050 off the lands is what his rifle likes.
 

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