Whats the story on flat primers?

[upacreek]

While doing barrel break in I shot some federal and winchester factory loads. I noticed the primers were brass colored. They flatten out completely compared to my cci 250 primers. Should I look for flat primers at all when looking for pressure signs and just keep giong until I get a sticky bolt or ejector mark? I have never loaded past the flat primer condition cause that was what I was taught. I cant decide if factory primers are just weaker than cci or if factory loads are hotter than what I load.
Any input would help. Thanks.

 

[upacreek]

If it matters the gun is a M70 in 7RM, 26" #5 fluted barrel. Shooting 160gr and heavier.

 

[trebark]

Generally, a flattened primer is a pressure sign.

 

[rdsewell]

I don't think I would be overly concerned about flat primers. But when you start seeing fire pin craters you better wow up. Just my experience

 

[blacknzr1]

I don't think I would be overly concerned about flat primers. But when you start seeing fire pin craters you better wow up. Just my experience

no offence, but I would say the opposite. for example my Remington 700 craters all primers, its because of the large firing pin hole, not excess pressure. therefore the flattened primers is a more accurate way of judging pressure over cratering.

 

[gohring3006]

I don't get concerned with flat primers in factory ammo or new brass the case is sized to fit in all rifles so with the loose headspace the primer can be slightly ejected out of the pocket then slammed back in when fired thus flattening it usually stops after its fire formed to your chamber. This is only true with factory new brass not once fired stuff if you get flat primers with reloads you are approaching max pressures

 

[Mikecr]

+1 gohring3006
And I'll add that pressure 'signs' are not necessarily pressure 'problems'.
It isn't a problem until it actually is.

 

[upacreek]

Most my guns are winchester m70's. They all crater the firing pin to primer area enough to catch a finger nail on it enough to know its there. I have always ignored that. Stopping at flat primers is normal for me, but i havent reached factory velocities in most cases with the 7WSM. My 7RM matches factory velocities but i havent had one ejector mark or sticky bolt. So should I keep going or stop at the flat primers?
Also are some primers softer than others? I have only used cci250 so far cause I have bricks of them. Just looking for some feedback. Thanks.

 

[Canadian Bushman]

You said you were doing barrel break in? If there is oil residue left in the chamber from cleaning it will show high pressure signs when there otherwise wouldnt be. Check the cartridge's primers after a few rounds and then see how they look.

There are other things that can cause flattened primers besides pressure so its always good to look out for the sequence of events.

Slight flattening of primers
Flattened primers
Ejector marks
Ejector swipes
Heavy bolt lift
Sticky bolt.

When your gradual increasing of loads causes these events. Typically in this order, you can bet your getting into high pressure. Also if your shooting over a chrono, you will notice jumps in velocity that again reflect the increase in powder.

 

[MagnumManiac]

Most my guns are winchester m70's. They all crater the firing pin to primer area enough to catch a finger nail on it enough to know its there. I have always ignored that. Stopping at flat primers is normal for me, but i havent reached factory velocities in most cases with the 7WSM. My 7RM matches factory velocities but i havent had one ejector mark or sticky bolt. So should I keep going or stop at the flat primers?
Also are some primers softer than others? I have only used cci250 so far cause I have bricks of them. Just looking for some feedback. Thanks.

Yes, all brands of primers differ in hardness and heat. Federal are normally softer than other brands, but not always, Winchester magnum primers are hotter than Federal magnum primers, etc, etc.
CCI are probably the hardest of all primer brands.
Primer cratering, unless other excessive pressure signs are present, are normally caused by a gun condition, not a load condition. Recently manufactured rifles by Remington and Winchester have a small bevel machined into the firing pin hole, why I don't know (I did ask), this is the cause of cratering in these rifles, not the size of the hole itself.
As far as your loading goes, if you have loaded to the book max and seen no indications of excessive pressure, then only you and your experience should tell you if it's safe to do so, not ANYONE ELSE, if you need to ask, then maybe you should not go past book max. There are a few things you need to know, which would take more space than is available here.

Cheers.
gun)

 

[upacreek]

, if you have loaded to the book max and seen no indications of excessive pressure, then only you and your experience should tell you if it's safe to do so, not ANYONE ELSE, if you need to ask, then maybe you should not go past book max. There are a few things you need to know, which would take more space than is available here.

Cheers.
gun)[/QUOTE]

Not to sound ungrateful for everybodies advice, but did you really just call me stupid? First, I have been reloading for 20 years with no problems. The people who taught me (before internet wizards) didnt know anything about being precise or gave a crap about being infinately accurate. I was taught to look at the primer for max pressure signs. I have never had a sticky bolt or ejector marks. So as I am relearning how to do everything (from scratch it feels like) it helps to ask questions so it is crystal clear. So YES, "anyone else" can tell me what their experience is, and I will listen and DO what I feel is safe and right. My original question was to figure out if the other primer manufacturers are softer or harder or the same as the cci brand I use. And I want to know if all the guys who talk about sticky bolt lift or ejector marks are ignoring the primer being flat. The velocities I am seeing have been noticeably lower than book or what other people claim to acheive. What I am trying figure out is how far max should be pushed. So YES, there is enough room here, start typing if you have the answers.......this guy wants to learn more than I was taught. If that is a problem, sorry.

 

[davkrat]

no offence, but I would say the opposite. for example my Remington 700 craters all primers, its because of the large firing pin hole, not excess pressure. therefore the flattened primers is a more accurate way of judging pressure over cratering.

Ditto. Base starting loads crater every primer I have tried in one of my Rem 700's

 

[bikehe]

This is a good question as I recently did some reloads for my 30/30 using federal standard large rifle primers. I loaded 10 with the new hornady 140gr copper bullets, cant remember exactly what they were called. Anyways using the latest ADI load data I was showing slight flattening but interestlngly all loads from min to max had cratering. I thought the new projectiles were causing higher pressures so I did another 10 and ran them over a chrony. The min load was about 150 fps below max velocity and the max load was 50 fps below book data. From this I just assumed the primers were soft and perhaps with a larger firing pin hole helped cratering also. I still dont understand though why it never happened before using federal primers as the only thing Ive done differently is changed projectiles. When these are fired Im going to try some CCI primers

 

[MagnumManiac]

Wasn't inferring that you are stupid, inexperience does not imply to me stupidity, I apologise if that is how you took it.
Primer appearance is not a good indicator of excessive pressure because different brands behave differently at differing pressures.
The best 2 indicators of excessive pressures are brass case appearance, firstly the expansion line location. If you compare a start load fired case to a max load fired case, you will notice that the expansion line is CLOSER to the web of the case due to more pressure, if comparing the same lot of brass. Secondly, ejector/extractor marks will show up pressures are excessive regardless of whether the primers are flat or not. Embossing of the head of the case with machining marks off the bolt face can indicate excessive pressure if a lower load did not have them appear, but it may just be that the machining marks are quite deep too.
The rifle will also tell you that pressures are excessive if you have stiff bolt lift accompanied by other marks on the brass, but also sticky extraction is a sure sign of excessive pressure if you know the chamber was clean and dry before firing that shot, oil in the chamber will cause sticky bolt lift and sticky extraction, it may also leave ejector/extractor marks due to excess bolt thrust.
The brass case tells you far more than primer appearance.

Hope this helps.

Cheers.
gun)