Field Test: CCI 400 vs. CCI 550

[Nick_C_S]

Earlier this month I inquired about whether or not CCI 400's are actually the same primer as CCI 550's - as heard here quite a few times over the years.

Unclenick chimed in with:

. . . Twenty years ago, the lady answering the phone at CCI told me CCI's employees all bought the 400s for both rifle and magnum handguns as the cup and priming mix and its quantity were all the same . . .

I stated I would run a field test; and today, I have the results . . .

Firearm is an AR-15 style sport rifle. 16" (or 16 1/2" maybe?) bbl. 1:7 twist.
Bullet is a Hornady 55gn FMJ-BT with Cannelure (Hornady bullet #2267).
OAL = 2.197" seated and collet crimped at the cannelure.
Case is Lake City "LC 16" twice fired. Trimmed to 1.750" and primer pocket de-crimped.
Propellant is 23.8 grains of AA2230.
10-round samples, both.

CCI 400: ...........CCI 550:
Low= 2759 .......Low= 2766
High= 2848 ......High= 2852
Average= 2813 ..Average= 2815
ES= 88.32 ........ES= 86.71
SD= 23.15 ........SD= 29.18

I would consider that to be statistically insignificant. I would expect two 10-round samples of identical ammo to vary more than that.

I know this doesn't prove CCI 400's and 550's to be the same, but they sure seem to perform pretty darn close.

Feel free to chime in.

[Unclenick]

Thanks for running that. The only possible statistically significant difference (95% confidence limits) was in the SDs. Changing the estimating method to the Xi(n) coefficient for extreme spread (it is a less accurate method), I got SDs estimated at 28.68 and 28.19 for the 400 and 550, respectively. So the standard method estimate for the 550 at 29.18 is in very close agreement with the Xi(n) method, while the 23.15 number for the 400 is lower than that method expects. Dividing 23.15 by 28.68, it is 0.807 times the Xi(n) expected value based on the extreme spread. In a 10-shot sample, the 95% confidence limit is at 0.811 times extreme spread, so it is still close to not being statistically significant if the Xi(n) estimate is to be believed. But it's not as accurate as the standard method at this sample size, so it is close enough that it could easily go away with additional sampling. So you still have pretty good evidence of the sameness of the two primers. I wasn't sure they would be the same twenty years after that phone call, but you have it looking like they are.

I have wax bullets and new Starline 38 Special cases I was going to drill out to try for comparison, but it looks like it might be a waste of effort. The only other question is, did you get to weigh these to confirm the cups and anvils have the same weight?

[74A95]

Originally Posted by Nick_C_S

I know this doesn't prove CCI 400's and 550's to be the same . . .

You’re right, this doesn’t. And you never will with this method.

The defining characteristics of whether the two primers are the same, is their chemical composition and amounts. See what you quoted from Unclenick. The “ . . . priming mix and its quantity were all the same . . .” That is what must be tested to determine if they are the same.

You tested whether the primers have the same effect. That’s a completely different thing. And on just one load. Different primer formulas could have the same effect on your load.

And you have no controls. You didn’t try primers from other manufacturers. You didn’t try primers that you KNOW are different, such as lead-free primers. They might produce the same speeds and SD.

These are the necessary controls to run if you’re going to compare effects of primers. And you need to try it on much more than one load. Different powders, and in different calibers, can change the results.


I asked CCI this same question about the 550 and 400 primers being the same. This is what they said:


<[email protected]>

August 16, 2016

They are not the same primer, there are differences in the primer and you should follow published loading data. The web has some very dangerous information on it and anything that you use should be published and tested data.

I followed up and asked about what the difference was:

August 18, 2016

There is differences in the mix.

Justin M./Technical Service Rep.
2299 Snake River Ave.
Lewiston, ID 83501
Alliant/Blazer/CCI/Speer
 (800)379-1732

[Nick_C_S]

Good information Unclenick. Perhaps a bit in the weeds for my simple mind and that's okay. If it's any help, here's the actual velocity readings for each shot:

CCI 400:
2848; 2809; 2828; 2805; 2759; 2818; 2815; 2806; 2830; 2809.

CCI 550:
2852; 2766; 2822; 2801; 2836; 2778; 2838; 2802; 2807; 2848.

I first shot 10 rounds with factory ammo; then ran a lightly oiled (Remoil) patch through the barrel.

Shot the 10 CCI 400 rounds; then re-conditioned the barrel again with the patch. Then shot the CCI 550 rounds.

Also, the fired primers look virtually identical (I only recovered 9 of the 10 CCI 400's). I have a pic but didn't feel like fighting with Photobucket. Besides, it's just a pic of 19 primers that all look pretty much the same.

[Nick_C_S]

74A95: My original post here omitted some context. I had a previous post regarding this issue on Sept 2nd that gave more detail of my issue and goal.

Yes, I was curious if a CCI 400 is the same as a CCI 550. But moreover, I wanted to know if the two were interchangeable in 223 Remington loads. That question has been answered to my satisfaction.

I have about 150 CCI 400's. I have almost 3000 CCI 550's.

I was pretty good about stocking up on components when we had a sane administration keeping the markets stable. But in the case of primers for AR-15 223 Rem, I wasn't. I bought a brick of 400's to get me started (I was new to the rifle world). But it quickly came to my attention that slam-fires are possible with CCI 400's (has yet to happen to me, btw), so I started looking for No.34's (I think that's what they're called) while passing by 400's. Never found them. In the mean time California virtually banned sporting rifles and so I decided to dismantle mine and gave up on loading and shooting them.

I have since moved to the free state of Idaho where I have picked up where I left off with 223 Rem load work ups - minus an abundant supply of primers.

I thought some perspective was in order - at the risk of shear boredom . Thanks for listening.

[74A95]

Originally Posted by Nick_C_S

Yes, I was curious if a CCI 400 is the same as a CCI 550. But moreover, I wanted to know if the two were interchangeable in 223 Remington loads. That question has been answered to my satisfaction.

Sounds good.

Originally Posted by Nick_C_S

But it quickly came to my attention that slam-fires are possible with CCI 400's (has yet to happen to me, btw), so I started looking for No.34's (I think that's what they're called) while passing by 400's.

CCI #34 primers are large rifle.

CCI #41 primers are small rifle, and what the .223/5.56 uses.

[Nick_C_S]

CCI #41 primers are small rifle, and what the .223/5.56 uses.

Thanks for the clarification. I kinda thought I had that wrong.

[ChimpMunk20]

Personally, I considered them interchangeable in most cases. What prompted the inquiry was the latest glut (relatively) of small pistol magnum primers. If they were indeed exactly the same, why would CCI package them in SPM packaging? Why not just sell them as much higher demand small rifle?
My suggestion is for CCI to just publish something and end the speculation. They could say "Don't interchange them, they are different composition" Or " They are the same composition, but don't interchange them" Or " Interchange them at your own risk"
I suspect the true reason CCI is silent on the issue is that the actual composition changes regularly and it would create a liability issue for them.
But, if that's the case, they could just say that as well. I don't see any benefit to them to just let the speculation run wild.

[akinswi]

Interesting, I was always under the impression you could use a small rifle primer in a pistol cartridge and not the other way around.

Was under the impression that the primer cups were harder in a rifle primer vs pistol primer.

[cdoc42]

A friend called me from a local gun shop and I was on speaker phone. He asked if we needed small pistol primers and I said, "yes, always." He said they were $12 for 100.
I said, "that's $120 a thousand; that's nuts. We can use Small Rifle Primers." Immediately, in the background, the LGS staffer said, "They're $15 a hundred." I said, "I'll sit tight until the price drops."

[Nick_C_S]

"I'll sit tight until the price drops."

I can now too. Now that I know my 550's will do what I need them to do.

During the Obama/Sandy Hook shortage, I lived in California. That started in early 2013. At least where I lived at the time, primers never did really recover. So it'll be interesting to see how our current situation unfolds, while also living in a new state.

[tjmga]

Nick
Not a statistician and I didn't stay in a Holiday Inn last night. My problem is I have a Sig 226 40SW and no more CCI 500 SP primers. I do have CCI 400 SR primers. Ran the following quick test and here are the results.

180 gr Nosler HP #44885
6.0 gr. CFF-Pistol powder
WW brass, 4 times fired
COL = 1.125"

CCI 500 SP
AVE VEL = 1008
ES =38
SD = 16

CCI 400 SR
ACE VEL = 1002
ES = 39
SD = 9
10 shots each. All primers fired first time.
I am not recommending anything or disagreeing with any manual, but I am shooting my 226.

[Nick_C_S]

I didn't stay in a Holiday Inn last night.

That gave me a good laugh.

Glad your Sig is running well on the 400's.