Why Large Rifle Magnum Primers?

[Harrys]

When reloading my 30/30 and 45/70 always large rifle primers were called for no matter which powder was used. When I started reloading my .500 S&W magnum all the Hodgdon powders called for large rifle magnum primers when all other powders called for the use of large rifle primers.

I wrote Hodgdon several times and have never received a reply on why the use of the large rifle magnum primers. So, I decided to do some testing to see if there was a difference. Keep in mind my testing was by the seat of the pants not scientific at all.

First test I loaded up some Hodgdon powders as recommended with large rifle magnum primers. The outside temperatures were 30 degrees on my first test. A 75-yard target iron sites using a BHA .500 carbine and 25-yard target using a BFR .500 revolver. Then I did the same test with standard large rifle primers and did not see any changes in accuracy or burn rate based on cases.

I completed the second test the same as the first except the outside temperature was 83 degrees. Again, there were no difference in accuracy of powder burn when comparing the cartridges.

I searched the WWW and could not find any reason why the large rifle primers were only used in Hodgdon powders. I did find in Europe and other countries they only used large rifle primers in the .500 S&S cartridges no magnum primers. The question still remains why I did find an UK guy that did extensive testing on primers. However, it did not answer the question why?

Here is his site which does help understand the difference between large rifle and large rifle magnum primers. But still does not answer the question why? Any thoughts form the group?
Large Rifle Primer Performance by Laurie Holland | Target Shooter Magazine

 

[Pale Ryder]

Maybe to insure more consistent ignition. I’ve read that H110 can be finicky when extremely cold, maybe some of the other Hodgdon powders are as well. Sorta along the lines of why some say to use 209’s made specifically for inline muzzleloaders.

 

[Doco Overboard]

I read for ball type powders and temps below 20 degrees in a Speer reloading manual a magnum type primer should be used.
The text does not, however distinguish for pistol or rifle cartridges
Other useful information gained from government laboratories could be found in Small arms Design and Ballistics. Townsend Whelen.
I think it's vol II

 

[ohen cepel]

Did they chrony the same or comparable?

 

[Harrys]

Did they chrony the same or comparable?

Based on the tests done from Laurie Holland with a 308 each primer manufacturer was a little different. Also, the magnum primers choreographed less than the standard primers.

 

[trickg]

A friend of mine has been looking for Large Magnum rifle primers for a bit with no luck. He's loading for 300 Win Mag. I don't know what powder he's using, but he believes that in order to maintain the accuracy at distance he has with this load that he needs the magnum primer vs the standard large non-magnum rifle primer.

I've looked into this in the past and the articles always seem to be a mixed bag. Some articles claim there's a substantial difference, and other articles claim next to no difference, and yet others claim that ignition is based in part on who the manufacturer is, and that standard primers from one make generate a bigger ignition spark than mag primers from another.

 

[chilipeppermaniac]

A friend of mine has been looking for Large Magnum rifle primers for a bit with no luck. He's loading for 300 Win Mag. I don't know what powder he's using, but he believes that in order to maintain the accuracy at distance he has with this load that he needs the magnum primer vs the standard large non-magnum rifle primer.

I've looked into this in the past and the articles always seem to be a mixed bag. Some articles claim there's a substantial difference, and other articles claim next to no difference, and yet others claim that ignition is based in part on who the manufacturer is, and that standard primers from one make generate a bigger ignition spark than mag primers from another.

Interesting, G

More questions from me to follow

 

[Doco Overboard]

I think maybe one day Ill load up some experimentation rounds both with magnum and non magnum primers and no powder in a worn government barrel using a rimmed case.
Then try and determine how far they travel down the bore and be easy to knock out.
Something else I want to do is cut a rifle barrel off at the neck of the case so that just the bullet sticks out with a full charge then fire the cartridge. I guess that would be a crime though for making a short barreled rifle, idk.
I bet a 30 cal bullet winds up as big as a dime maybe. Capturing the bullet would have to get worked out too to have a good look at it afterwards, see what happens and all that.
Otherwise I read the article that Harrys put up and it just seems to be another laundry list of numbers like people do all the time. Just like he said.

 

[lazarus]

Based on the tests done from Laurie Holland with a 308 each primer manufacturer was a little different. Also, the magnum primers choreographed less than the standard primers.

My little bit of testing on rifles, it SR vs SRM with 223 and 6.5 Grendel is SRM produce slightly lower velocity with ball and stick powders, seem to produce better SD and ES, but are less accurate than standard primers. SD and ES both appear to be about 25% better for most loads, but accuracy seems to be, counterintuitively, about 25% worse. Even trying ladders for both types of primers

For example 26.7gr of CFE223 and a 69gr SMK with CCI SR primers will put 5 rounds in to a .8” group for my Howa with an SD of 22fps. Using magnum primers the most accurate was 26.6gr of CFE223, but 5 rounds is into a hair under a 1.1” group and SD is 16fps. I don’t recall velocities, but I think the magnums are about 40fps slower.

Don’t know if it is the case, but I am wondering if part of the difference is that the hotter primer allows the bullet to start moving forward before the powder charge is combusting as rapidly. On lower case filled cartridges, the little testing I did with pistols magnum primers seem to get about 10-20fps more velocity on average, but even using the same powder charge in rifle cartridges I seem to see about 10-30fps lower velocity. And it is pretty consistently lower average.

I have not checked to see if it is because magnums are reducing the high velocity fliers or not.

 

[ohen cepel]

I think maybe one day Ill load up some experimentation rounds both with magnum and non magnum primers and no powder in a worn government barrel using a rimmed case.
Then try and determine how far they travel down the bore and be easy to knock out.
Something else I want to do is cut a rifle barrel off at the neck of the case so that just the bullet sticks out with a full charge then fire the cartridge. I guess that would be a crime though for making a short barreled rifle, idk.
I bet a 30 cal bullet winds up as big as a dime maybe. Capturing the bullet would have to get worked out too to have a good look at it afterwards, see what happens and all that.

Could do that with a Contender or Encore pistol to keep things above board and less annoying.

 

[Doco Overboard]

Don’t know if it is the case, but I am wondering if part of the difference is that the hotter primer allows the bullet to start moving forward before the powder charge is combusting as rapidly.

Thats just what happens. Like shaking a soda bottle with a cork in it instead of a tightly screwed cap.

 

[ras_oscar]

I would be more concerned with the peak impulse load than the muzzle energy. Something that can (as far as I know) only be measured under lab conditions. That impulse (or exceeding it) is what turns breeches into fragments. By the time the projectile exits the barrel a lot of those energy readings have leveled out across the length of the barrel.

 

[Harrys]

A friend of mine has been looking for Large Magnum rifle primers for a bit with no luck. He's loading for 300 Win Mag. I don't know what powder he's using, but he believes that in order to maintain the accuracy at distance he has with this load that he needs the magnum primer vs the standard large non-magnum rifle primer.

I've looked into this in the past and the articles always seem to be a mixed bag. Some articles claim there's a substantial difference, and other articles claim next to no difference, and yet others claim that ignition is based in part on who the manufacturer is, and that standard primers from one make generate a bigger ignition spark than mag primers from another.

Yes LRMP like hens' teeth, I was able to get 1k of them for 90 bucks last week went to buy more and they were sold out.

 

[Harrys]

My little bit of testing on rifles, it SR vs SRM with 223 and 6.5 Grendel is SRM produce slightly lower velocity with ball and stick powders, seem to produce better SD and ES, but are less accurate than standard primers. SD and ES both appear to be about 25% better for most loads, but accuracy seems to be, counterintuitively, about 25% worse. Even trying ladders for both types of primers

For example 26.7gr of CFE223 and a 69gr SMK with CCI SR primers will put 5 rounds in to a .8” group for my Howa with an SD of 22fps. Using magnum primers the most accurate was 26.6gr of CFE223, but 5 rounds is into a hair under a 1.1” group and SD is 16fps. I don’t recall velocities, but I think the magnums are about 40fps slower.

Don’t know if it is the case, but I am wondering if part of the difference is that the hotter primer allows the bullet to start moving forward before the powder charge is combusting as rapidly. On lower case filled cartridges, the little testing I did with pistols magnum primers seem to get about 10-20fps more velocity on average, but even using the same powder charge in rifle cartridges I seem to see about 10-30fps lower velocity. And it is pretty consistently lower average.

I have not checked to see if it is because magnums are reducing the high velocity fliers or not.

I loaded up some .500 specials for the revolver with LRPs and LRMPs will be interesting to see the results both in recoil and accuracy.

 

[lazarus]

I loaded up some .500 specials for the revolver with LRPs and LRMPs will be interesting to see the results both in recoil and accuracy.

Good luck! Let me know the results, I am very curious.

 

[85MikeTPI]

I posted this thread a bit back from Genix data:

Large Rifle (vs magnum large rifle) primers

[Edit: so in looking at the GENIX site more, I believe what I found below are the difference between a LRP and a "military" LRP. I found specs on a primer they spec for the 338LM which has both the thicker cup and a MUCH larger charge, which is what I would guess is a US equiv MLRP] PRIMER...

www.mdshooters.com