The effects of changing primers

[ButterBean]

^^^ I thought it was 60gr for Large Rifle? Or below 20degF.

So why do they even make a small rifle magnum primer?

It may be 60, Like I said I have never paid any attention to it

 

[Stammster]

For rifle primers, I was under the impression the amount of primer ignition material was the only thing that varied, not the thickness or harness of the cup. If is does vary, it's got nothing to do with pressure or piercing.
I've never heard selecting a rifle primer type based on chamber pressure. In fact, I run standard LR primers in my 270 Win with hot loads - and never had an issue. The 270 Win is about as high of a psi cartridge there is (65kpsi).

 

[Justice1327]

Thank you for the info, and I was aware of those general rules, but I thought by now we would have something a little more concrete or sciency.

 

[Justice1327]

For rifle primers, I was under the impression the amount of primer ignition material was the only thing that varied, not the thickness or harness of the cup. If is does vary, it's got nothing to do with pressure or piercing.
I've never selected a rifle primer type based on pressure. In fact, I run standard LR primers in my 270 which is about as high of a psi cartridge there is (65kpsi).

What's interesting is over the last several years I've called federal/CCI/Winchester/Remington and ask them very similar questions over the years and depending on who you get you will get a different answer. I wish each of them would publish their white papers on exactly the Brisance of their primers, height, diameter, chemical makeup etc...
IMHO, I think the difference that people notice are simply a matter of quality control of that specific primer during that run. In other-words if you found the perfect primer for said cartridge and then used the same manf primers from a lot that was five years previous or five years in the future would it do the same?

 

[L.Sherm]

For rifle primers, I was under the impression the amount of primer ignition material was the only thing that varied, not the thickness or harness of the cup. If is does vary, it's got nothing to do with pressure or piercing.
I've never heard selecting a rifle primer type based on chamber pressure. In fact, I run standard LR primers in my 270 Win with hot loads - and never had an issue. The 270 Win is about as high of a psi cartridge there is (65kpsi).

I can guarantee you put a 6.5 rem primer in a creed. running a upper end load or similar cartridge and it will Pierce.
Same goes for a cci400 vrs 450

 

[L.Sherm]

Here's a good chart on primer cup thickness.
You will notice the LR primer thickness are all the same

 

[ButterBean]

For rifle primers, I was under the impression the amount of primer ignition material was the only thing that varied, not the thickness or harness of the cup. If is does vary, it's got nothing to do with pressure or piercing.
I've never heard selecting a rifle primer type based on chamber pressure. In fact, I run standard LR primers in my 270 Win with hot loads - and never had an issue. The 270 Win is about as high of a psi cartridge there is (65kpsi).

The primer cup material varies from each manufacturer with federal most always being the softest and it does have a lot to do with piercing issues and almost everyone runs standard primers in the 270

 

[Justice1327]

I can guarantee you put a 6.5 rem primer in a creed. running a upper end load or similar cartridge and it will Pierce.
Same goes for a cci400 vrs 450

I have experimented with small primer and large primer Lapua 6.5 Creedmoor brass. Each of my handloads loads get me 2900 to 3000 ft./s which is definitely on the upper end. I saw very little velocity variation between the two. however, I did see lower ES/SD using the small primers. I even drilled out the small primer brass to the same size/hole as would be in a large primer case. This actually netted me slightly higher velocity and still maintain the lower ES/SD. If small primers are thinner I didn't notice it.

 

[L.Sherm]

I have experimented with small primer and large primer Lapua 6.5 Creedmoor brass. Each of my handloads loads get me 2900 to 3000 ft./s which is definitely on the upper end. I saw very little velocity variation between the two. however, I did see lower ES/SD using the small primers. I even drilled out the small primer brass to the same size/hole as would be in a large primer case. This actually netted me slightly higher velocity and still maintain the lower ES/SD. If small primers are thinner I didn't notice it.

Which SR did you use?

 

[Justice1327]

Which SR did you use?

CCI and Fed Match
Small test lots of only 20 shots each so not a huge amount of testing but for me it was enough.

 

[L.Sherm]

CCI and Fed Match

Which CCI SR primer you will see the 450 is the thickest and the Fed match are the thickest Fed SR

 

[Justice1327]

Which CCI SR primer you will see the 450 is the thickest and the Fed match are the thickest Fed SR

400

 

[Gunpowder]

Large rifle are supposed to be the same thickness, but like someone posted federal are perhaps softer. Thus I've read warnings about their use in semi-autos, especially the m1. Now I don't know this from personal experience but I do know I use cci 34 only in the Garand. I have a dpms 300 saum that will pierce any lr primer with loads using bullets over 168 gr, including the 34s. Thus the reason many ar10 sized rifles in calibers other than 308 now use the smaller firing pin size, usually called a high pressure bolt. My dpms g2 uses that and no issues.

Small rifle I can tell for sure, cci 400 are thinner and pierce easily. I have a tc compass 204 that due to sloppy firing pin fit is a piercing sob. So no more 400s in my 204 loads for that rifle.

Btw, thanks to the link from the article above, that's a good read.

 

[Justice1327]

Also Primer thickness is not indicative of hardness or tensile strength.