Pressure signs not showing at Max load

[Johnslam]

I've seen cratered primers from Hornady black Grendel loads.

 

[PBR driver]

Just looking at fired cases will not give you an accurate reading.
The only way we reloaded have a judging pressures is by measuring a factory case fired in your chamber with a 0.0001" micrometer.
When you fire several cases of factory ammo, measure your case expansion , average this number.
When you are starting with your minimum load and working up, measure your fired hand load with the 0.0001" micrometer, once your hand loaded cases expand the same as your factory cases then you have reached the maximum load in your chamber and components.

 

[jbo829]

Sorry for my ignorance but I have an older Remington 700 in 280 and all and I mean all factory ammo I shoot thru the gun shows primers just like his so does that mean all the factory loads are over pressure in my rifle

 

[nicholasjohn]

Because it's likely a function and idiosyncrasy of rifle itself, Iv several that display cratered primers, but not over pressured. Now if the primer is horribly flat and the case has ejector swipes and a sticky extraction, we'd better stop immediately with that load and back off the charge, to safer level.

Some rifles will even do that with factory loads, which are rarely loaded over max pressure. ( The lawyers keep the pressure out of the "law-suit" range.) A looser than normal fit of the firing pin in the hole in the bolt face can cause this type of cratering. I've read that this can also affect accuracy, but I don't know how that works. This is one of the reasons some guys will use a bushing to fix a firing pin hole that is too big. It may be that they want the pin to hit the primer perfectly dead-center every time. Anybody know for sure about that one ???

 

[Clem Bronkoski]

going faster is not always a good thing. just me, but I would focus on grouping more than speed some times going faster can cause your grouping to open up.

 

[Don A Parsons]

I'm 1 to 1.2 grains less max charge on my 3 rifles,,, the brass looks good,,, I can get 2 to 3 reloads by neck sizing only...

Normally I have to bump the shoulder back on the 3rd or 4th time I reload the cases...

The 3 rifles shoot good groups close to max charge,,, that's not saying I can't take them up to max,,, but I like the idea of longevity and accuracy...

Good catch on the bubble of melted material on the head stamp,,, I've seen this a few times due to my own fualts... Ha...

"""If""" I see those melted bubbles on my brass,,, the rest get pulled and the melted head stamp cases go into the garbage brass bin...

I hate wrecking my Lapua brass,,, so I'll take the less ft-per seconds any day...

Just me i guess

 

[skipglo]

Sorry to disagree Skipglo. That is a dangerous statement! You or anyone else can't make that statement with out having the rifle in hand and the opportunity to work up a load. He is already showing pressure signs at 40.5

He could have a tight barrel, a tight neck, bullet seated into the lands, etc. Any number of things could cause his rifle to be on the edge of too much pressure.

I have always had a policy of not quoting loads that are not in a book somewhere. If you do, you can be held liable if someone hurts themselves. Let the manufactures take that risk.

Actually... read it again! NO PRESSURE SIGNS

 

[MNbogboy]

I have seen with Hornady 6.5 brass they won't show pressure signs, they just pop the case heads. I got 250 rounds of the nicest looking once fired Hornady Amax factory loads back from when they were having pressure problems. Second loads looked good but 3rd the bright ring showed up and 1 split about half way around the case. I don't push 6.5 Hornady brass to the max anymore, I'll hot rod my .260 AI first.

Your problem here sounds like incipient head separation and is not a pressure related problem, but rather an instance where fired cases are being resized to a much shorter than necessary measurement from base to shoulder. This is not to be confused with overall case length. The usual cause for the oversizing is improper sizing die setup.
Die setup instructions that come with the die are usually the culprit.
Do some searches on here & other forums for proper "bump" setup and your case head problems should go away.

Sorry to hijack but an important issue.

Randy

 

[skipglo]

Sorry to disagree Skipglo. That is a dangerous statement! You or anyone else can't make that statement with out having the rifle in hand and the opportunity to work up a load. He is already showing pressure signs at 40.5

He could have a tight barrel, a tight neck, bullet seated into the lands, etc. Any number of things could cause his rifle to be on the edge of too much pressure.

I have always had a policy of not quoting loads that are not in a book somewhere. If you do, you can be held liable if someone hurts themselves. Let the manufactures take that risk.

That's the problem here so often...we think we read.... not we did read...but you are right in the one instance... probably shouldn't quote a load...re-read it...then comment again!

 

[Nitroman]

Sorry for my ignorance but I have an older Remington 700 in 280 and all and I mean all factory ammo I shoot thru the gun shows primers just like his so does that mean all the factory loads are over pressure in my rifle

No. Low pressure loads allow movement of the case at the firing pin impact to the front of the chamber, as the case swells and pressure builds, the primer can be pushed back, then as the case stretches to the face of the bolt, a tiny bit of primer cup metal can extrude into the firing pin hole as the pin rebounds. It looks remarkably like very high pressure.

 

[MNbogboy]

In agreement with many on here that if you are seeing ejector marks you most likely are already over maximum design pressure.
If your primer pockets loosen substantially in the first two to four firings, again you are probably exceeding the pressure that the brass is good for.
Soft brass, barrel/chamber dimensions & condition, temperature, powder lots, bullet type material and lot numbers all affect pressure with a host of other factors.
Every rifle is different and reloading manuals take that into account. Hot rodding any cartridge is usually a recipe for poor case & barrel life as well as the potential for catastrophic failure.
After being at this game for near 55 years I've broken every rule in the book and thank God I still have my eyes and life. Blowing a primer is an awakening that no reloaders should have to experience. Twice to me with firearm damage once both caused from pushing the envelope.
The new guys are lucky to have the internet and forums for research. But as we all know we can't believe it all.
Randy

 

[Sam Summey]

You already have primer cratering, I suspect the temp is above 90 degrees. The book max load is calculated based on safe pressure at elevated temperature. Does it shoot under a minute, then STOP. If it doesn't shoot that well drop back a grain and move up in tenth grain increments until you reach max again. If it doesn't improve before max reduce 10% and start over again. The max load should not be exceeded unless you want to stretch the action and blow the headspace.

 

[Indian7953]

And that is dependent on choice of primer.

[/QUOTE]

You already have primer cratering, I suspect the temp is above 90 degrees. The book max load is calculated based on safe pressure at elevated temperature. Does it shoot under a minute, then STOP. If it doesn't shoot that well drop back a grain and move up in tenth grain increments until you reach max again. If it doesn't improve before max reduce 10% and start over again. The max load should not be exceeded unless you want to stretch the action and blow the headspace.

 

[Indian7953]

I have a 7 mm Rem mag that calls for a max charge of 71 grs. of powder but it shoots 69.7Gr. max, if I go over that it starts showing brass on the bolt face similar to yours. I also have a Winchester 264 magnum that craters all primers no matter what the charge is. It looks to me like you are right there at max load don't go over it.