Muzzle Velocity and Magnum Primers

Status
Not open for further replies.

denton

Member
Joined
Feb 22, 2011
Messages
2,198
Location
Free state of Utah
Once again, the curiosity gene stirred, leading me on another investigation.

I have a couple of old jars of Accurate 2520. In past tests, 55 grain bullet 223/5.56 loads reached a plateau beyond which more powder did not yield more muzzle velocity. Since components are in short supply, I wondered if I could concoct a load that was not troubled by the plateau, and that would be good fodder for my M4gery. And it would be especially nice if the load did not require magnum primers, since I have plenty of standard small rifle primers and fewer magnum primers.

The test involved shooting matched pairs of 62 grain bullet cartridges over the range of interesting loads, from low 223 loads to a bit into 5.56 territory. One cartridge in each pair used a standard CCI 400 primer, and the other used a magnum CCI 450 primer.

Here are the data:
202303.jpg

The good news is that neither load reached a plateau. If there is a plateau with this bullet, it is somewhere beyond 27 grains of powder. I can use standard or magnum primers throughout the range.

The interesting discovery is that there is no detectable difference between the MVs of cartridges with standard primers and those with magnum primers. It would also be reasonable to infer that there is no difference in peak pressure.

If you take the difference between each CCI 400 point, and the matching CCI 450 point and then average those numbers, the CCI 450 shows an average advantage of 3 FPS, which is so small as to not be distinguishable from normal random variation, i.e., not statistically detectable.

Here is the analysis of the data:
2250 paired T.gif

Notes: Cartridges fired in random order, to wash out any effects of temperature, fouling, etc. In my old data, when MV stops increasing, so also does peak pressure. MV data captured with Labradar. Ambient temperature 68 F. Beautiful day at the range.
 
I have also let curiosity drive me to doing some basic test. The following was all new Remington brass. The loads were all done weighing each charge on my old Lyman M5 scale. This was all done about 10 years ago. The loads were H335 at 26.1 grains under Sierra 53 grain HPBT match bullets. The rifle is my custom Remington 700 with a 1:12 twist.

Primer%20Test%201.png

The Chronograph was my trusty Oehler 35P.
CCI%20Primer%20Test%201.png

The primers all CCI with the CCI 450 and CCI #41 being magnum primers.

All ten shot groups were shot at 100 yards and my focus was more on the chronograph that holding and squeezing but the following ten shot groups were what I got.
223%20Primer%20Test.png

Denton thanks for sharing, stuff like this always fascinates me.

Wow, I see a correction is needed. While I dated the target 1-6-16 I also noted 73 degrees F. My guess is we don't have 73 F days up here in NE Ohio in January so it should read 6-1-16 or June 1st 2016. :)

Ron
 
I have also let curiosity drive me to doing some basic test. The following was all new Remington brass. The loads were all done weighing each charge on my old Lyman M5 scale. This was all done about 10 years ago. The loads were H335 at 26.1 grains under Sierra 53 grain HPBT match bullets. The rifle is my custom Remington 700 with a 1:12 twist.

View attachment 1104695

The Chronograph was my trusty Oehler 35P.
View attachment 1104696

The primers all CCI with the CCI 450 and CCI #41 being magnum primers.

All ten shot groups were shot at 100 yards and my focus was more on the chronograph that holding and squeezing but the following ten shot groups were what I got.
View attachment 1104697

Denton thanks for sharing, stuff like this always fascinates me.

Wow, I see a correction is needed. While I dated the target 1-6-16 I also noted 73 degrees F. My guess is we don't have 73 F days up here in NE Ohio in January so it should read 6-1-16 or June 1st 2016. :)

Ron

My take away is although the BR primers gave the lowest SD, they were all pretty consistent.

The 41s gave the highest velocity, kinda significantly.
 
Thank you for the data.

IMO we don't use a magnum primer or a #41 primer because we are looking for a velocity increase, we use them to try and reduce the possibility of a slamfire in a semi-auto rifle with a floating firing pin. (AR and the like)

Many of us realize a magnum primer my insure a better powder burn but not increase velocities, at least I do.
 
IMO we don't use a magnum primer or a #41 primer because we are looking for a velocity increase, we use them to try and reduce the possibility of a slamfire in a semi-auto rifle with a floating firing pin. (AR and the like)

Many of us realize a magnum primer my insure a better powder burn but not increase velocities, at least I do.

That's technically wrong, on both counts... and yes, I'm nitpicking here. :)

1) Standard and Magnum primers, generally, have the same cup and anvil design, the Arsenal primer, specifically, is designed to resist slamfires... it is my understanding the anvil is shaped differently. The Arsenal primers are considered Magnum primers, yes, but a normal primer (standard or Magnum) is not necessarily designed to resist slamfires.

2) A Magnum primer is designed to guarantee ignition of some powders... in several different environments, like arctic temperatures, or big charges of hard to ignite powders. Once a powder starts to burn... it's on its own.
 
I did a similar test many years ago... 5.56mm and the 69grn SMK, with H335 and CCI 400 and 450 primers. Some load data suggests a Magnum primer for a ball powder like H335... I was curious to see if I could see a difference... or, worst case scenario, the standard primer would cause erratic ignition. Long story short, the standard primer gave me MORE velocity, and better SD's than the Magnum primer, and this from 5 cartridges of each fired in my 20" H-bar and my 16" RRA carbine. It was not a significant velocity increase, 25fps in the carbine, 5fps in the rifle... but it was definite. It is interesting to note that the velocity increase was greater between the barrels using the Magnum primer (110fps vs 90fps) all else being equal... so the Magnum primer had some effect on the powder ignition and burn rate
 
IMO we don't use a magnum primer or a #41 primer because we are looking for a velocity increase, we use them to try and reduce the possibility of a slamfire in a semi-auto rifle with a floating firing pin.

@Charlie98 , You may pick all the nits you want but I'm just wondering one thing, where in my post did I say anything about the cup on the magnum or #41 primer being thicker?

I didn't, and neither did you. You stated that we use 'them,' that is... 'a Magnum primer or a #41 primer'... to 'try and reduce the possibility of a slamfire.' I said that's not true. What I said was the standard and Magnum primers are built, basically, the same, the difference being the primer compound. The Arsenal primer... the #41 in your statement... IS designed differently than a standard or Magnum primer... as I mentioned, I believe it has a different anvil. I said nothing about the thickness of the cup.

I'll be the first to admit I'm wrong if someone can show me where I'm wrong... but this is my understanding of the differences in Arsenal primers... not a thicker or harder cup.
 
When it comes to questions regarding CCI primers I have o0n occasion just emailed CCI "Ask The Expert" and they have always been great at responses. Rather than just toss something out in the forums it's easier to just quote the experts since they make the stuff. Just for example the primer stuff crops up frequently.

Me:
Would the CCI BR-4 Primer be classified as a Standard or Magnum small rifle primer? Likewise the CCI #41 primer, would it be Standard or Magnum classified?

CCI:
Ronald, primer specifications are below.
Small rifle primers

#41......................................Mil. Spec. primer, thick cup, magnum primer charge, angle of anvil change.

BR4.....................................thick cup, standard anvil and standard priming mix held to a tighter tolerance.

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

Another example:

Me:
Regarding CCI #34 primers. The question has come up or it has been stated that CCI #34 primers are the same thing as CCI 250 Large Rifle Magnum primers. While I know the CCI #34 is a magnum primer I believe it is not the same as other large rifle magnum primers in that it has further reduced sensitivity. Would that be correct and is the priming mix different than standard large rifle magnum primers.

CCI:
Ron, here are the differences in the 2 primers. So the anvil angle change is the difference, this keeps the free floating firing pins from causing slam-fires in AR style platforms. This does make it so that a light strike will have a less of a change of going off.

CCI-250............................ Magnum primer, Mag primer mix, thick cup, standard anvil.

#34/7.62MM................... Mil. Spec. primer, thick cup, magnum primer charge, angle of anvil change.

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

It's always easier to simply quote a manufacturer. I have had other responses from Jason who seems to be their go to guy on email replies. :)

Ron
 
Status
Not open for further replies.
Back
Top