6.5 PRC Over pressure with H1000 and 156 Bergers

GBWS

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Aloha All

Just wanted to post this here to see if anyone has anything similar happen to them. With this powder/bullet combo. Thanks in advance!

Have a buddy who hads a 6.5 PRC giving him issues on a hunt right now.

Here's his load specs:
New adg brass,
F215M
60gn h1000,
Berger 156 eol,
coal 3.0735,
cbto 2.360 = 15 thou off the lands

He told me he spoke to berger to get chg weights for H1000 & this cartridge/bullet combo. He was given 54.5 start 60.4 Max. He did note that they wouldn't give him brass brand they were using.

He did load work up from 56-60.5, 60.5 had very slight bolt lift resistance, Not heavy etc! Settled on 60 gr load less than .5 groups.

Below is what he had from LR for velocity. Until yesterday he had shot roughly 30 rounds with no pressure signs etc. Temps here are mid to high 80's

So he checks zero yesterday before today's hunt and first 3 shots all blown primers heavy bolt lift. He's scratching his head and bummed because he only took 20 rounds of 143's with him which he's already shot 10 lol.

Only thing that comes to mind is if the ADG Brass has a different volume than what berger was using (I'm thinking hornady?) Therefore the ADG Max is less than what berger is using. BUT...he worked up loads and none showed high pressure signs.

Idk what ppl seeing for velocity with this bullet but I told him that what he's getting is up there. But idk much about the PRC. I have a 6.5x284 n only doing 2950 with 130's.

He's got meat in the cooler so I told him I'd try and ask if anyone has ideas on the forums.

Sorry, his rifle is built on a tikka action. Started out as 300 Win mag. Had gunsmith rebarrel it with a proof sendero 7.5 twist 26" Put it in a woox exacts stock l believe.
 

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Yes ADG brass takes less powder. He was at dangerous pressure level. Drop it back down and try again. RL26 and N560 N565 work great in prc and will give him better velocity's at safe pressure.
Looks too me he is a little hot and probably jammed into the lands I've got 2 6.5 prcs 60 grs of powder with a 156 gr bullet adg brass back off and work back up
 
Just a thought but how confident is his .0015 off lands measurement? Could be he's actually in the lands causing pressure spike. I had this happen before with the Hornady OAL gauge. I measured again and I was touching the lands and not 0.0010 off.

This might not be the problem but worth a double check.
You mean .010" (10 thou) and .015" (15 thou) off the lands...
 
What velocity is he running with that load? I run 59.5 of RL25 with a 140 and I get pressure signs in the 80+ degree range. No pressure in the 70ish and below range and I'm running mine almost 3100 after the barrel broke in. If I remember right I hit pressure just over 60 gr with 140s with h1000. Mine grouped better with the RL25 to my disdain but she's dirty accurate.

*edit - I see, that's quick with the 156!
 
Aloha All

Thanks much for all your replies l greatly appreciate it 🙏🏾

According to him load workup was done with ADG brass. Shot load multiple times roughly 30+ times with no issues until yesterday morning.

He also said he feels fairly confident about his cbto reading but then again it's a reference. And he was the first to admit that things happen and maybe he overlooked it. But to shoot over 30 + rounds with no issues then 3 in a row like that idk seems weird to me.

Good news is his 143 gr load is shooting great. He got 5 deer today. Will go back out for sheep n more deer tomorrow.

Thanks again for all your help

Aloha

Dom
 
Aloha All

Thanks much for all your replies l greatly appreciate it 🙏🏾

According to him load workup was done with ADG brass. Shot load multiple times roughly 30+ times with no issues until yesterday morning.

He also said he feels fairly confident about his cbto reading but then again it's a reference. And he was the first to admit that things happen and maybe he overlooked it. But to shoot over 30 + rounds with no issues then 3 in a row like that idk seems weird to me.

Good news is his 143 gr load is shooting great. He got 5 deer today. Will go back out for sheep n more deer tomorrow.

Thanks again for all your help

Aloha

Dom
 
We have several 6.5 PRCs in our shop and from what we've seen 60 grains of H1000/3100 FPS+ with a 150 class bullet is a spicy load. If the barrel still has less than 100-200 rounds on it, it's likely speeding up too. Back it down and try jumping the bullets more. .060+ The hybrid style Bergers will shoot great well off the lands and create less pressure, which makes for a more consistent shooting rifle over the course if the barrel's life.

Some reading materials
PRC Load Development - https://www.rockymountainhunting.com/b/reloading-for-65-prc.html
Bullet Jump - https://precisionrifleblog.com/2020/04/28/bullet-jump-research-and-load-development-tips/
 
Comparators can't necessarily be *ahem* compared to another's necessarily since they are a reference point.

But, for my PRC and Hornady comparator, 156 EOL @ 2.360" CBTO is right at the lands. 0.188" freebore
[/QU If you are correct even with a 143 gr eldx that would put you around . 080 th into the lands I have a . 145 freebore factory 2.950 is right there according too 2.360 on the 156 that would put you. 313 into the lands unless my math is off I stand too be corrected
 
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