Talking Primers

[OpFor1]

We're your slam fires with the 200s which are 0.019" thick and not recommended for semis, 205Ms which are 0.0225" thick, or 205MARs (AR Match) which are 0.025" thick and also harder?

Yes they were. I was either ignorant of that fact at the time or just not paying attention to what primers I grabbed, but I learned real quick.
Then I had to talk to the range master who was also a police officer. He was under the impression I modified my weapon illegally and I had to prove I did not.
Ruined my whole day. And needless to say he and I are not friends after the way he talked to me while he was accusing me of a crime I did not commit.

This was out of an AR that I used on patrol and on the ranch, so it probably had more slop in the bolt and firing pin area than most allowing the firing pin to travel further in the bolt and easier from the wear.

[Jeepster18_88]

I've never experienced a problem with CCI 400s. I've been using them for yrs in 223 and 7.62x39. It's recommended to use the thicker cups but they weren't available at the time I started loading for the ARs. TBH, they're still hard to find at LGS. I've read a lot in various reloading manuals over the years, I think I have Hornady's first manual even, and it's been stated repeatedly that switching primers can greatly affect pressure. Most load data for most of my cartridges use non magnum primers so that's what I stick to. Most agree that pressure could jump as high as 10k PSI between primer/powder combos which I assume ( I could be completely wrong) might change the specific burn rate of a powder in a particular cartridge. Either way, 10k PSI over max listed isn't a good idea even if it's less than a proof load. Maximum pressure also puts more wear on everything but doesn't give a proportionate velocity advantage. I also suspect (again I might be completely wrong) that hot primers might be the reason some have issues with excessive pressure while using published data. Basically people are turning a 50k PSI load into a 55k to 60k load. I work up each load carefully regardless, inspecting each piece of brass after each shot, even if everyone else says it's safe to use. There's so many variables that can change things already, the primer is one of the few that you can keep the same. I'm very curious if there is any information about difference in the pressure build between magnum and non magnum primers. Pressure rising faster early or late, or whether one has a smoother pressure build or more spikey.

I'm not recommending using standard thin cup primers and it's honestly something that is probably brand specific, which is why Lee only recommends certain primers with some equipment. I'm only saying that the standard CCI 400 has never shown any indication that it shouldn't be used in the 8 ARs that I've used them in. As always, use your own discretion.

[Mad Charlie]

Yeah, that's why we work up, and if we change something, we work up again.

My manuals only go back to 1951, the year I came into the world.

[Longtubeman]

found a graph
calhoonprimers02[1].png

[BobinNC]

I've never experienced a problem with CCI 400s. I've been using them for yrs in 223 and 7.62x39. It's recommended to use the thicker cups but they weren't available at the time I started loading for the ARs. TBH, they're still hard to find at LGS. I've read a lot in various reloading manuals over the years, I think I have Hornady's first manual even, and it's been stated repeatedly that switching primers can greatly affect pressure. Most load data for most of my cartridges use non magnum primers so that's what I stick to. Most agree that pressure could jump as high as 10k PSI between primer/powder combos which I assume ( I could be completely wrong) might change the specific burn rate of a powder in a particular cartridge. Either way, 10k PSI over max listed isn't a good idea even if it's less than a proof load. Maximum pressure also puts more wear on everything but doesn't give a proportionate velocity advantage. I also suspect (again I might be completely wrong) that hot primers might be the reason some have issues with excessive pressure while using published data. Basically people are turning a 50k PSI load into a 55k to 60k load. I work up each load carefully regardless, inspecting each piece of brass after each shot, even if everyone else says it's safe to use. There's so many variables that can change things already, the primer is one of the few that you can keep the same. I'm very curious if there is any information about difference in the pressure build between magnum and non magnum primers. Pressure rising faster early or late, or whether one has a smoother pressure build or more spikey.

I'm not recommending using standard thin cup primers and it's honestly something that is probably brand specific, which is why Lee only recommends certain primers with some equipment. I'm only saying that the standard CCI 400 has never shown any indication that it shouldn't be used in the 8 ARs that I've used them in. As always, use your own discretion.

I know that it has been stated repeatedly that changing primers can cause extremes jumps in pressure. But further inspection and tests, show it may be mainly myth and lawyer driven. Below is just a few of the tests, which show remarkable consistency between primers.

https://youtu.be/ypI6D-i57uk

https://youtu.be/ZPu0DzIgKNk

https://ar15armory.com/forums/topic/165243-newbes-epic-small-rifle-primer-test-a-test-of-9-different-primers/

Now don't get me wrong, I'm a careful reloader, so I'm not advocating willy nilly switching primers without first working up that new load up from below. That's just reloading 101. But I also fail to see huge pressure spikes, and huge increases in velocity when mag primer were substituted with regular primers in the rifle cases illustrated above. Now accuracy can be affected, but what I was astonished at was the SR primer test in 6.5 Creedmoor.
6 of the SR primers tested had a total variance in muzzle velocity of 4 FPS.......Astonishing really. Anyway all this in IMHO and YMMV. And as always the number one key to reloading is be safe.......

[Bfglowkee]

[lazyengineer]

I know that it has been stated repeatedly that changing primers can cause extremes jumps in pressure. But further inspection and tests, show it may be mainly myth and lawyer driven. Below is just a few of the tests, which show remarkable consistency between primers.

https://youtu.be/ypI6D-i57uk

https://youtu.be/ZPu0DzIgKNk

https://ar15armory.com/forums/topic/165243-newbes-epic-small-rifle-primer-test-a-test-of-9-different-primers/

Now don't get me wrong, I'm a careful reloader, so I'm not advocating willy nilly switching primers without first working up that new load up from below. That's just reloading 101. But I also fail to see huge pressure spikes, and huge increases in velocity when mag primer were substituted with regular primers in the rifle cases illustrated above. Now accuracy can be affected, but what I was astonished at was the SR primer test in 6.5 Creedmoor.
6 of the SR primers tested had a total variance in muzzle velocity of 4 FPS.......Astonishing really. Anyway all this in IMHO and YMMV. And as always the number one key to reloading is be safe.......

On a practical level, this is closer to my experience in general. If I take a regular load, and switch around primers, I don't in general observe any difference in apparent pressure sign, velocity, or accuracy. If I take a warm load, and switch around primers - again, I haven't really observe any difference. But YMMV, of course.

I will say, on light charges and difficult to light powders, I have observed differences there. A few case studies:

9mm with BlueDot. That slow powder would light slowly and leave much unburned powder with a regular primer. With a magnum pistol primer, it went up about >50 FPS. Which is a lot. Still don't like BlueDot in 9mm, but if you have to use it, be sure to use a magnum primer.

H335 speed ball powder, with 40 gr bullets at below minimum loading. Long story, but ended up with some mixed powders, and a mountain of 40 gr bullets for dirt cheap. So for grins, did some experimental load development and made light rounds out of it for ultra-low recoil 50 yard spec 3-gun style blaster ammo of serviceable accuracy for IPSC targets at that range. Ran these around 1-2 gr below book minimum. Found that in cooler temperatures, a light charge of a ball powder like that, would light funny or sometimes outright squib with a regular primer (CCI400). Switching to CCI41 (i.e. magnum) on the same load ran more accurate and was 100% reliable. This is where I learned light loads can sometimes just not ignite correctly, due to lack of sufficient heat and pressure build-up. Inspection showed that often the powder was visibly scorched by the non-magnum primer, but it just didn't light off .

Just my own experience.

[Mad Charlie]

Your experience mirrors mine in my early days (70's) of handloading with ball powders.

Since then I have a general rule, if it is ball powder, it gets mag primers from the start.