Are deez primers flat?

[Caligula36]

Got some boxes here of S&B Tactical 6.5 Creedmoor, 140gn FMJBT. Accuracy is meh, better with a cold barrel. But for factory loads, do these primers look flattened?

[JagerDog]

Not overly so (no extrusion), but I'd say yes.

But reading primers is hardly an exact science.

[pacrat]

About par for factory stuff. Especially for S&B. Which IMO is a bit hotter than typical US made ammo.

Over the last 50 yr or so. I have found many factory primers flatter than I typically load.

[Caligula36]

Not overly so (no extrusion), but I'd say yes.

But reading primers is hardly an exact science.

For future knowledge, what do you mean by extrusion?

If these were my handloads, would you call this a stop sign?

I know it's all very subjective, trying to get a better understanding of what to look for.

[divingin]

Primers are not a great sole indicator of pressure. To use them, you have to be familiar with the primers cup thickness and hardness, cartridge to chamber fit, and how the firearm has historically affected the end result.

As a couple of examples, the same load (and same pressure) using "AR" or "military" primers may show nothing (primer appears as installed), whereas a Federal 210 will appear much like yours, due to thinner and softer cups.

Along the same line, a case with a shorter case base to datum (shoulder) measurement may allow the primer to back out of the case head further than a longer case would, before the case slams back against the breech reseating the primer. This often causes flattening that is not directly tied to high pressure.

I generally use marks on the case head (extractor or ejector marks) or a measurement of the case just above the web as an indicator of upper pressure limits. But a primer that is not flattened will generally also indicate a lack of pressure.

As to the "extrusion", I suspect Jager was talking about cratering (a raised "crater rim" around the firing pin strike.) That caused more by a poor firing pin to firing pin hole fit, but does take some pressure to form. My bench rifle at max pressure will cause ejector and extractor marks with no cratering. Depends on the rifle (hence the knowing your rifle thing above.)

[JagerDog]

For future knowledge, what do you mean by extrusion?

If these were my handloads, would you call this a stop sign?

I know it's all very subjective, trying to get a better understanding of what to look for.

When you get a ridge at the firing pin indentation.

[Caligula36]

Good info, thanks.

Primers are not a great sole indicator of pressure. To use them, you have to be familiar with the primers cup thickness and hardness, cartridge to chamber fit, and how the firearm has historically affected the end result.

As a couple of examples, the same load (and same pressure) using "AR" or "military" primers may show nothing (primer appears as installed), whereas a Federal 210 will appear much like yours, due to thinner and softer cups.

Along the same line, a case with a shorter case base to datum (shoulder) measurement may allow the primer to back out of the case head further than a longer case would, before the case slams back against the breech reseating the primer. This often causes flattening that is not directly tied to high pressure.

I generally use marks on the case head (extractor or ejector marks) or a measurement of the case just above the web as an indicator of upper pressure limits. But a primer that is not flattened will generally also indicate a lack of pressure.

As to the "extrusion", I suspect Jager was talking about cratering (a raised "crater rim" around the firing pin strike.) That caused more by a poor firing pin to firing pin hole fit, but does take some pressure to form. My bench rifle at max pressure will cause ejector and extractor marks with no cratering. Depends on the rifle (hence the knowing your rifle thing above.)

Someone on another forum mentioned that excessive headspace could also allow something like this. The rifle is a Ruger Precision Rifle gen 2, original bolt and barrel. I know Ruger isn't known for great quality control, but is this something that I might want to check?

[ar15barrels]

Someone on another forum mentioned that excessive headspace could also allow something like this. The rifle is a Ruger Precision Rifle gen 2, original bolt and barrel. I know Ruger isn't known for great quality control, but is this something that I might want to check?

Excessive headspace can be from either the firearm or the ammo or both.
You can have both the ammo and the firearm being within specs but still have enough headspace that you get excess headspace signs when the ammo is near min spec and the firearm is near max spec because the two different tolerances are stacking against each other.
In an ideal world, the firearm would be near minimum and the ammo would be near max length so that the tolerances stack together instead of apart.

[smoothy8500]

mentioned that excessive headspace could also allow something like this.

It could allow the primer to "back out" on ignition and get squished as the case expands....

[divingin]

Someone on another forum mentioned that excessive headspace could also allow something like this. The rifle is a Ruger Precision Rifle gen 2, original bolt and barrel. I know Ruger isn't known for great quality control, but is this something that I might want to check?

You certainly could, but (this is my opinion) what will it get you? [As an aside, a new cartridge can be headspace tested with scotch tape: layer tape on the case head and see when the bolt ceases to close. Measure tape to get your clearance with that cartridge. Not exactly precision, but it gives you an idea.]

There is a range of acceptable headspace (bolt face to shoulder) for all factory rifles. Some will be long, some will be short, but hopefully all will fall within the min and max lengths (not true, but I did say hopefully.) This means the amount of "play" in your rifle with a round chambered may be anywhere from "none" to "the difference between min and max allowable", depending on where your chamber falls.

In addition to the above, factory ammo tends to be loaded to minimum base to shoulder spec (in order to chamber in any rifle, no matter where on that scale the chamber lies.)

Lastly, if you shoot factory ammo, you have no control over what length your brass is. I've taken to the belief that factory ammo is loaded for a single firing, with no expectation that the brass will be reloaded. One and done. Understandable from a manufacturer's viewpoint, but not exactly real-world, as a lot of once-fired factory brass gets reloaded.

Those who reload can choose to allow the base to shoulder measurement grow and then start sizing to keep that measurement (fireforming, with a sizing routine that maintains that length.) Factory shooters are stuck with whatever the factory deems is right. Reloaders who consistently return brass to factory dimensions usually run into problems with brass failing (as do those who follow the die manufacturer instruction on setting up sizing dies, but that's a different thread.)

FWIW, when starting with virgin (unfired) brass, I load the bullet out far enough to hit the rifling on the first firing or two, in order to keep the case against the bolt face and blow the shoulder forward. It speeds up the fireforming, and prevents the false pressure signs that a short case may show. It also tends to stretch the case body less than firing the short case normally, which adds to case longevity.

With a Savage rifle and their barrel nut system, you can adjust your headspace fairly easily (much more so than a shouldered barrel as in a Rem 700.) The question would be whether it's worth the trouble to do so.

Hope this helps.

[opticsauthority]

To ensure the safety of your firearm and ammunition, carefully inspect fired casings for signs of excessive flattening around the primer pockets. This can be done visually or with a magnifying glass, comparing them to unfired casings of the same ammunition type for reference. Additionally, measuring the height of the primers with a caliper can provide insight; significantly shorter primers compared to unfired ones may indicate flattening.

If there's any uncertainty or concern about the condition of the primers, it's advisable to seek guidance from a qualified gunsmith. They can professionally inspect the casings and provide expert advice on whether further action is necessary.

Several factors, such as the number of rounds fired and storage conditions, can impact primer appearance. Over time, primers may naturally flatten after multiple reloads, and extreme temperatures can also affect their appearance. However, flattened primers can potentially indicate dangerous levels of pressure, prompting the need for caution. If suspicion arises regarding primer flattening, it's crucial to discontinue use of the ammunition and have the firearm inspected by a qualified gunsmith to ensure safety and prevent potential hazards.

[divingin]

To ensure the safety of your firearm and ammunition, carefully inspect fired casings for signs of excessive flattening around the primer pockets.

"Around primer pockets" means the case head. That's already flat. If you mean imprinting on the brass, you should say so.

If you mean the primers themselves, that's already being discussed.

Additionally, measuring the height of the primers with a caliper can provide insight; significantly shorter primers compared to unfired ones may indicate flattening.

Again, details matter: You must be talking about measuring height of removed fired primers, and comparing them to new ones (at leaast I hope you are - measuring the primers height in the fired case is meaningless, as the primer moves.) Given that the anvils will come into play (and that's discounting any deformation of the cup from the act of decapping), I don't see this as being anywhere near meaningful without (at the very least) one additional step.

Over time, primers may naturally flatten after multiple reloads,

You load your primers more than once?

However, flattened primers can potentially indicate dangerous levels of pressure,

Or it may not. Hence the conversation.

[smoothy8500]

Or it may not. Hence the conversation.

I think that "Authority" should stick to "Optics" (maybe?), since they don't make sense with any of their responses across the forum....

[ar15barrels]

Arguing with a bot won't get you anywhere.
Didn't you notice how the 3 paragraphs of text above were not even written by a human?
That's AI at work.
The bot is just here to build posts for the company deploying it.

Check out the posting pattern for the most recent posts:

https://www.calguns.net/calgunforum/search.php?searchid=111601160

Never fully comprehendable.
No followup when engaged.

"Around primer pockets" means the case head. That's already flat. If you mean imprinting on the brass, you should say so.

If you mean the primers themselves, that's already being discussed.



Again, details matter: You must be talking about measuring height of removed fired primers, and comparing them to new ones (at leaast I hope you are - measuring the primers height in the fired case is meaningless, as the primer moves.) Given that the anvils will come into play (and that's discounting any deformation of the cup from the act of decapping), I don't see this as being anywhere near meaningful without (at the very least) one additional step.

You load your primers more than once?




Or it may not. Hence the conversation.