Signs of pressure on primers

[tripledeuce]

I'm working up some loads at the moment for my 6.5x55. I wondered if anyone wanted to give a second opinion on the primers in the photo below (CCI br2).

The left is just below adi max, the middle is about 5% above, the right is 10% above adi max.

I can see that the middle and the right are flattening off, but I don't find them particularly alarming. Planning on doing more work around these load weights unless anyone thinks they look bad? Bolt lift and extraction were not noticeably different accross any of the loads tried.

[kickinback]

Measure your case head diameter. When it starts getting bigger..........


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[Camel]

Those primers need to be a lot flatter than that before you run into dangerous territory, have had some that completely filled the primer pocket and had a small ridge on the outside, it was still not a max load. Primers aren't the best way of telling pressure, it should only be used as a bit of a guide.

[MISSED]

Can you rechamber the fire round ?

[LoneRider]

my brothers 6mm used to smear the primers over the rear of the case
he had a 6 foot flame out the barrel
mind you,i had flash burns 5 foot behind him and off to the side

[The Raven]

my brothers 6mm used to smear the primers over the rear of the case
he had a 6 foot flame out the barrel
mind you,i had flash burns 5 foot behind him and off to the side

Maybe back it off 0.1 of a grain...

[tripledeuce]

Thanks, fired rounds go back in the chamber no worries. Case head of virgin brass is 0.475". Anything fired is 0.477".

Looks like I'm safe for now, which is nice as it cracked the 3,000fps mark:

[bimbo]

as long as there was no other pressure signs those primers look fine to me, not even starting to square off on the edges etc. If you are getting good accuracy then leave it but if not stoke it up a bit more. In general I have found ADI max's to be pretty conservative

[trevort]

my brothers 6mm used to smear the primers over the rear of the case
he had a 6 foot flame out the barrel
mind you,i had flash burns 5 foot behind him and off to the side

Maybe back it off 0.1 of a grain...

Lol


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[Ned Kelly]

G'Day all,
certainly any expansion of the case head just forward of the extractor groove is cause for concern, I've generally found any heavy bolt lift on opening a fire case means that the action AND case has stretched enough that the case is too long and tight in the chamber after firing = hard to open.
Now all that means is that something (action, bolt, bolt lugs, etc) has been deformed enough to let the case stretch at peak pressure. It may not be the case's at fault but it will show either cratered/flattened primers, pierced primers, case head expansion, ejector marks etc and usually hard to open.
All these need to be considered together and you can sometimes live with them (cratered primers) or you back off by about 1% of the powder load. Especially if the load was developed in cooler autumn winter spring conditions and your going hunting in Mid February! Ambient temperature of the ammo and the rifle may cause pressures to spike. So dont go leaving you ammo on the dash in the sun! You wouldn't do that to your dog, more so with your ammo!
Cheerio Ned

[stinkitup]

Triple what recipe and action you shooting? Those primers look about perfect I have seen swede ones flatter with winnie primers which seemed soft compared to feds and cci's. The middle and right pretty much look the same. Whats the group like?

Most swede loads are conservative so generally with modern action going a little hot is safe as long as working up. My old swede was very flat in the primers and sticky bolt over 42 grains of 2209 with 140s max is 44 and know plenty of modern actions shooting 44+.

My savage ackley is 3 to 4 grains over with still room to move with further testing with russian primers and 2213sc but different kettle of fish.

Ryan

[Seddo]

As everyone has said, those primers aren't flat.

[tripledeuce]

The max I've tried is 51g of 2213sc under a 140g AMax. Action is a Sako 75 so it should be able to handle he hotter loads. Accuracy is nothing to get excited about at around 0.8moa for the hotter loads. All the brass has been brand new so far, I need to see if I can fit any more powder in the fired cases, otherwise I will be giving 2209 a try.

[stinkitup]

Pretty damn impressive for the 140 in the standard case.

I need to stoke the AI up

Wish we had the rl26 here I think it is.

[Turkeyshooter]

Hi there tripple duce, given that you're using the excellent Lapua brass, your results look to me to be OK.
If you were to use that load with some other brass of lesser quality or unknown provenance, I would back it all off by at least 10%
That six and a half has been known to start grass fires!

hope this helps
John