It would be helpful if you listed what exact measurment devices you used to reach your conclusion...which chronograph, what pressure testing equipment, and the data generated by that equipment. As your post reads, you may just be doing physical observations..."same apparent recoil, same level of report", etc.
Magnum primer questions?
- Thread starter Prof Young
- Start date
Road Clam said:
There are lots of tests showing a particular gun or load doesn't follow the general trend or is even made worse by going to a magnum primer. So you can't put it to bed with one example. It has to be tried on a chambering by chambering, powder by powder basis. It doesn't even always follow that only spherical propellants are affected. I advised a fellow on the CMP forum using an 80% fill load of one of the 4895's in 30-06 in a Garand to try a magnum primer because he had high velocity SD and poor group size. He reported substantial improvements in both after making the switch. But I wouldn't conclude from that example that I could count on it making a difference to all Garand shooters using the same powder. It's just one of the things you need to try when tuning a load.
I would expect, since even standard primers (domestic ones, again, not all the foreign ones) now make the hotter sparks, too, that if you have a short powder space and a powder that isn't too slow and you have good case fill, the extra start pressure from the magnum primer's greater gas production would be less useful than in a large overbore magnum rifle firing an even slower burning (more heavily deterred) powder. Indeed, with short enough cases you have to watch out for the magnum primer unseating the bullet and worsening velocity SD and ignition regularity.
The chronograph is your friend in assessing what primer is best to use. The primer that consistently produces the lowest velocity SD's is doing best for you, even if you have to retune your charge weight to get the smallest groups with it.
dahermit:
I recently posted this and questions and discussion about primers comes up frequently so here is my little science experiment.
I used four types of primers, all were CCI manufacture, there were two standard primers CCI 400, CCI BR-4 and two magnum primers CCI450, CCI #41. The cases were all LC 11 once fired brass, full length resized and trimmed to 1.750" Loaded to a COL of 2.230"
The bullets were Sierra 53 grain BTHP Match #1400.
The powder charges were all weighed and 26.1 grains of H-335 which depending on what you read could be considered a heavy load. The sierra 50th Anniversary Edition puts this just below a Maximum load of 26.8 grains.
The chronograph used was an Oehler 35P set with my skyscreens about 15' downrange of the muzzle.
The rifle was a custom Remington 700 series gun with a 26" barrel having a 1:12 twist.
The ambient air temperature was 73.0 degrees F and the actual ammunition temperature was at ambient air temperature.
The data is based on 10 shot strings with the shots approximately 1 min plus apart. The target was 100 yards downrange. I was more focused on getting the shots through my chronograph than holding and squeezing unfortunately.
The Ammunition:
The chronograph data:
The target:
About all this does is demonstrate my results using my rifle under a set of given conditions. Interesting is that the velocities did not really differ much between a magnum and standard primer at close to a maximum load. All of the cartridges extracted just fine and there was nothing out of the ordinary. The rifle, as nearly as I could discern, was no hotter when I finished than when I started and I shot 10 rounds before firing the 40 used for data collection. The numbers are what they are. I have no clue what the powder and primer lot numbers were but I doubt it matters as even if I recorded them I would have nothing to reference my data against.
Ron
I recently posted this and questions and discussion about primers comes up frequently so here is my little science experiment.
I used four types of primers, all were CCI manufacture, there were two standard primers CCI 400, CCI BR-4 and two magnum primers CCI450, CCI #41. The cases were all LC 11 once fired brass, full length resized and trimmed to 1.750" Loaded to a COL of 2.230"
The bullets were Sierra 53 grain BTHP Match #1400.
The powder charges were all weighed and 26.1 grains of H-335 which depending on what you read could be considered a heavy load. The sierra 50th Anniversary Edition puts this just below a Maximum load of 26.8 grains.
The chronograph used was an Oehler 35P set with my skyscreens about 15' downrange of the muzzle.
The rifle was a custom Remington 700 series gun with a 26" barrel having a 1:12 twist.
The ambient air temperature was 73.0 degrees F and the actual ammunition temperature was at ambient air temperature.
The data is based on 10 shot strings with the shots approximately 1 min plus apart. The target was 100 yards downrange. I was more focused on getting the shots through my chronograph than holding and squeezing unfortunately.
The Ammunition:
The chronograph data:
The target:
About all this does is demonstrate my results using my rifle under a set of given conditions. Interesting is that the velocities did not really differ much between a magnum and standard primer at close to a maximum load. All of the cartridges extracted just fine and there was nothing out of the ordinary. The rifle, as nearly as I could discern, was no hotter when I finished than when I started and I shot 10 rounds before firing the 40 used for data collection. The numbers are what they are. I have no clue what the powder and primer lot numbers were but I doubt it matters as even if I recorded them I would have nothing to reference my data against.
Ron
Ron,
I did a little playing with stats on your data. When you have a sample size of 10 the 95% confidence expectation is the extreme spread will be 3.077 times the SD or less. For all your strings but the #41 string, that was true. The #41 string went outside that range, indicating there was one outlier in it (a single sample with a less than 1 in 40 chance of showing up. So, I looked at which velocity was furthest from the mean, and that was the lowest velocity shot. I removed it and got an SD of 28.8. When I went through the other strings and removed the velocity furthest from the mean, the SD for the BR-4 was 29.0 (I am rounding to the nearest 0.1 fps here) for the #450 it was 31.5 and for the #400 it was 33.7. So I think, considering one outlier, your data actually shows the #41 produced the best ignition consistency.
It makes no obvious sense since CCI says the #41 is identical to the #450 other than the differently angled anvil feet used to bring the #41's sensitivity down to meet military sensitivity spec. You would expect their performance to match, but it didn't.
There are a couple of explanations. One is that the performance had no significant difference and that the difference was all within the range of random error. I ran Student's T-test between all the combinations and can tell you there is less than 95% confidence the difference between any of the first three strings is more than a random difference. But for the last set of #41 tests, there is better than 95% confidence its average is different from the BR4 and even greater confidence it is different from each of the other three. It would seem the #41 is your best choice, and it looks like the group backs that up.
The only thing I can think of that might skew the results is if the primers were not inside the nominal 0.002—0.004" reconsolidation (compression) beyond the point the anvil touches down on the primer pocket floor. But if they were, what you are seeing is that lot variation makes a greater difference to performance than the primer designation does. A very interesting finding.
Thank you for doing the test.
I did a little playing with stats on your data. When you have a sample size of 10 the 95% confidence expectation is the extreme spread will be 3.077 times the SD or less. For all your strings but the #41 string, that was true. The #41 string went outside that range, indicating there was one outlier in it (a single sample with a less than 1 in 40 chance of showing up. So, I looked at which velocity was furthest from the mean, and that was the lowest velocity shot. I removed it and got an SD of 28.8. When I went through the other strings and removed the velocity furthest from the mean, the SD for the BR-4 was 29.0 (I am rounding to the nearest 0.1 fps here) for the #450 it was 31.5 and for the #400 it was 33.7. So I think, considering one outlier, your data actually shows the #41 produced the best ignition consistency.
It makes no obvious sense since CCI says the #41 is identical to the #450 other than the differently angled anvil feet used to bring the #41's sensitivity down to meet military sensitivity spec. You would expect their performance to match, but it didn't.
There are a couple of explanations. One is that the performance had no significant difference and that the difference was all within the range of random error. I ran Student's T-test between all the combinations and can tell you there is less than 95% confidence the difference between any of the first three strings is more than a random difference. But for the last set of #41 tests, there is better than 95% confidence its average is different from the BR4 and even greater confidence it is different from each of the other three. It would seem the #41 is your best choice, and it looks like the group backs that up.
The only thing I can think of that might skew the results is if the primers were not inside the nominal 0.002—0.004" reconsolidation (compression) beyond the point the anvil touches down on the primer pocket floor. But if they were, what you are seeing is that lot variation makes a greater difference to performance than the primer designation does. A very interesting finding.
Thank you for doing the test.
Unclenick,
Thanks for taking my numbers further than I did. Yes, I also seemed to think there were a few quirks which other than speculation I sure can't explain. Sometimes when I do what I call little science experiments I get results in line with what I expect but every now and then I sit there wondering why something did what it did leaving me wondering what I did wrong. It's when what should be predictable results simply don't do as expected.
Yes, I even have an email from CCI telling me a #41 is the same as a 450 but with a slightly different angle on the anvil. Overall when I loaded these and did this the results were not quite what I expected. I like what you have provided and again thanks for taking things further.
I had hoped to get out and run an experiment on 100 rounds of 308 I have loaded where I did case weights and volumes. Unfortunately never got to it so when we get the warm weather back hopefully I can get that finished.
Ron
Thanks for taking my numbers further than I did. Yes, I also seemed to think there were a few quirks which other than speculation I sure can't explain. Sometimes when I do what I call little science experiments I get results in line with what I expect but every now and then I sit there wondering why something did what it did leaving me wondering what I did wrong. It's when what should be predictable results simply don't do as expected.
Yes, I even have an email from CCI telling me a #41 is the same as a 450 but with a slightly different angle on the anvil. Overall when I loaded these and did this the results were not quite what I expected. I like what you have provided and again thanks for taking things further.
I had hoped to get out and run an experiment on 100 rounds of 308 I have loaded where I did case weights and volumes. Unfortunately never got to it so when we get the warm weather back hopefully I can get that finished.
Ron