Why Large Rifle Magnum Primers for Hodgdon Powders?

[BigBolt]

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

 

[SKWERLZ]

I use standard LR primers even for my RUM cartridge.

 

[Doom]

The the 500 S&W Magnum is a 60,000 psi cartridge. Much higher than most pistol cartridges so pistol primers are not universally suited and safe. Hench the use of rifle primers. I would speculate that Hodgdon chose to use the LRM primers simply because the cartridge is considered a magnum.

 

[White Eagle]

I know that the use of LRM primers are suggested when using H110/W296 but first I have heard of all Hodgdon powders

 

[markm87]

I use Hodgdon and regular 210m and Win LR primers all the time. I actually avoid using the Magnum primers on the theory that the milder primer keeps SDs lower.

 

[DGP4]

I don't think Hodgdon calls for any particular type of primer. What they do when giving you starting and maximum loads for a particular bullet/powder combination is tell you what type of primer they are using. Looking at the load data for your caliber, I see they use both regular and magnum large rifle primers in their data.

 

[Laurie]

Hodgdon is not alone in this practice, albeit for rifle cartridges rather than an unusually high pressure revolver number. Norma Precision has long quoted the use of LRM primers for relatively small cartridges like 308 Win even for its fastest burning / smallest charge grades such as 200 and 201. Just been looking at Norma's 308 Win tables in its #2 Reloading Manual and the Winchester WLRM is the listed cap for example.

I suspect that @DGP4 has given the correct reason. The old rule applies nevertheless that if you deviate from the exact components quoted in manuals' pressure barrel-tested loads, you will likely get different results and pressures. This may be a small difference, but of course the concern is that it could be significant and in the direction of higher pressures with some components changes. I'd hardly have thought that a risk in this case however, and it may well reduce MV SDs going to a 'milder' primer. (In Norma's case R H VanDenburg who does most of Handloader magazine's Propellant Profiles powder reviews has done side by side tests with LRM and LR primers of some Norma loads and produced significantly reduced ES/SD values in smaller/medium size cartridges.)

 

[BigBolt]

I know that the use of LRM primers are suggested when using H110/W296 but first I have heard of all Hodgdon powders

Only in the .500 S&W loads

 

[BigBolt]

Hodgdon is not alone in this practice, albeit for rifle cartridges rather than an unusually high pressure revolver number. Norma Precision has long quoted the use of LRM primers for relatively small cartridges like 308 Win even for its fastest burning / smallest charge grades such as 200 and 201. Just been looking at Norma's 308 Win tables in its #2 Reloading Manual and the Winchester WLRM is the listed cap for example.

I suspect that @DGP4 has given the correct reason. The old rule applies nevertheless that if you deviate from the exact components quoted in manuals' pressure barrel-tested loads, you will likely get different results and pressures. This may be a small difference, but of course the concern is that it could be significant and in the direction of higher pressures with some components changes. I'd hardly have thought that a risk in this case however, and it may well reduce MV SDs going to a 'milder' primer. (In Norma's case R H VanDenburg who does most of Handloader magazine's Propellant Profiles powder reviews has done side by side tests with LRM and LR primers of some Norma loads and produced significantly reduced ES/SD values in smaller/medium size cartridges.)

Attached is some info that shows LRM primers actually produce lower FPS when tested. I have been doing a deep dive and there is a lot of talk about replacing standard primers with magnum primers by reducing the loads. Also, the thickness and design of the primers are the same other than a higher charge. I have been on sites like PowderThrough which shows to use any MFG large rifle primers where others said to use magnum primers. The only difference is they also show higher powder charges with the use of standard primers. Just more to ponder.

 

[Laurie]

Attached is some info that shows LRM primers actually produce lower FPS when tested. I have been doing a deep dive and there is a lot of talk about replacing standard primers with magnum primers by reducing the loads.

Yes, I know that piece rather well - I researched and wrote it!

What I said was that not all LRMs are 'hotter' than LRs as evidenced by comparative MVs. Some are, some aren't .............. and even where they didn't produce higher MVs as in the Rem 9 1/2M vs the plain 9 1/2, the magnum version can still produce larger ES/SD values as is the case here.

Vis a vis the Norma powder data in its manual, the WLRM this company seems to prefer is one primer I never found in the UK. Word has it that it is a very hot number indeed. The standard WLR is pretty 'hot' as my MV results show. (But who knows? - with primers I found that received wisdom is often wrong, and moreover I have plenty of experience that suggests primer rankings / performance change over the years, perhaps even between production lots! The WSR SR primer has changed remarkably over the last quarter century for instance.)

An exception to the general rule about standard vs magnum LR primers is that the Russian PMC/Murom LRM (KVB-7M) appears little different to the standard KVB-7 version, and whilst I sold off my SD ruining magnums years ago, I kept all my ancient PMC brand LRMs and still use them in 308 Win size cartridges with good results.

 

[Laurie]

and there is a lot of talk about replacing standard primers with magnum primers by reducing the loads

That's a very interesting point. I can't talk about LR/LRM versions, but have some experience with SR primed cartridges, in particular 223 Rem with 90s at very high MVs which I shot at national and international level in F/TR over 10 years ago. My base primer was the tough-cup, but mild PMC (Russian Murom manufactured) SRM or KVB-5,56M. I tried various alternatives and came to the conclusion that primer performance is VERY important in the 223 (since confirmed with other small designs and also seen very experienced professionals like Bill Alexander stress this from his experience of developing the Grendel and loading many thousands of cartridges for it). I'd tried the whole range of SRMs in the 223 and had been particularly disappointed by the CCI-BR4 a primer much lauded by the cognoscenti. It not only produced bigger groups / SDs, but added a fair few fps to the PMC SRM's MV. Simples, says I, I'll just lower the load to regain the PMC primed cartridge's MV and groups etc will be restored. They weren't - not anywhere near in fact!

So, it may work in bigger cartridges with LR / LRM primers, but there's an equally good chance that charge adjustment won't be the answer as there's more to the rifle-performance + cartridge combination issue than MVs alone. I came to the conclusion that one should try several primers in a key load, fine-tune the best and then stick to it like glue. Of course, easier said than done with the current supply situation.

 

[DGP4]

My much less scientific results jive perfectly with those of Laurie noted above. S&B LRPs outperform all other primers I have tried in terms of standard deviation. Sadly, I am down to the last 700 S&B primers I bought years ago. Similarly, my Winchester LRP are capable of producing higher velocity with the same charge and bullet than the Remington and CCI LRPs I have used. I think that when you work up a load for accuracy in any caliber, you have to factor in the performance of the primer. Obviously, the powder and bullet choice is the primary consideration, but the primer can add to the equation.

 

[The German]

I remember, for the .500 S&W, they started with LP primers and at some point switched to LR as they could handle the high pressure better, but no idea, why they ask for Magnum ones - I initially loaded my .500 with standard LR and later with LR Mag and did not experience any difference, but I also never measured pressure.

 

[BigBolt]

Yes, I know that piece rather well - I researched and wrote it!

What I said was that not all LRMs are 'hotter' than LRs as evidenced by comparative MVs. Some are, some aren't .............. and even where they didn't produce higher MVs as in the Rem 9 1/2M vs the plain 9 1/2, the magnum version can still produce larger ES/SD values as is the case here.

Vis a vis the Norma powder data in its manual, the WLRM this company seems to prefer is one primer I never found in the UK. Word has it that it is a very hot number indeed. The standard WLR is pretty 'hot' as my MV results show. (But who knows? - with primers I found that received wisdom is often wrong, and moreover I have plenty of experience that suggests primer rankings / performance change over the years, perhaps even between production lots! The WSR SR primer has changed remarkably over the last quarter century for instance.)

An exception to the general rule about standard vs magnum LR primers is that the Russian PMC/Murom LRM (KVB-7M) appears little different to the standard KVB-7 version, and whilst I sold off my SD ruining magnums years ago, I kept all my ancient PMC brand LRMs and still use them in 308 Win size cartridges with good results.

Thanks for your hard work and testing. I am not new to reloading but was new to the .500 S&W cartridge reloading as it is a fairly new one. What I have found there are a lot of contradictions even among manufacturers of powders, cartridges and bullets. From your testing I was able to glean that primers are not equal even among the same manufacturers. From my experiences testing both magnum and standard rifle primers in hot and cold weather the differences are minimal in the .500 S&W. I also recently tested the magnum primers in powders that recommended standard large rifle primers. I borrowed a chronograph and found there were minimal differences in values using minimum loads between the magnum and standard large rifle primers. I was very curious as large LRPs and LMRPs are hard to find. My 45/70 uses LRPs and may now try the LMRPs at least this will give me more options when the primers become more available.

 

[SKWERLZ]

Attached is some info that shows LRM primers actually produce lower FPS when tested. I have been doing a deep dive and there is a lot of talk about replacing standard primers with magnum primers by reducing the loads. Also, the thickness and design of the primers are the same other than a higher charge. I have been on sites like PowderThrough which shows to use any MFG large rifle primers where others said to use magnum primers. The only difference is they also show higher powder charges with the use of standard primers. Just more to ponder.

View attachment 1448466View attachment 1448467

One test doesn’t set the standard.
Variance in cartridge combinations and other factors are vast.

My findings in my 7mm and 338 were that standard LR primers were superior to magnums for ES.

 

[Diverjeff]

I'm down to 500 Fed 215M's and since I have 2,000 Fed 210M's I may switch over after watching Mark's video on primers in my 338LM.Since I'm a fair weather shooter these days and don't have to worry about cold/freezing temps.(and shooting a mild load of 88.5 grs. of H1000),according to Mark's testing I should be fine(he says he's using LR primers up to and including his .375 Gibbs with no ignition problems).Finding Fed 215M's has been impossible for me so far so I may not have a choice anyway.

 

[SKWERLZ]

I'm down to 500 Fed 215M's and since I have 2,000 Fed 210M's I may switch over after watching Mark's video on primers in my 338LM.Since I'm a fair weather shooter these days and don't have to worry about cold/freezing temps.(and shooting a mild load of 88.5 grs. of H1000),according to Mark's testing I should be fine(he says he's using LR primers up to and including his .375 Gibbs with no ignition problems).Finding Fed 215M's has been impossible for me so far so I may not have a choice anyway.

I’m running close to 100 grains of N570 in my 338 edge and switched to 210M’s after testing.

 

[Diverjeff]

I’m running close to 100 grains of N570 in my 338 edge and switched to 210M’s after testing.

That's good to know,thanks bro.

 

[ebb]

I had hangfires in my 7mmRUM when using large rifle primers. Magnum primers are designed to ignite large amounts of powder. People that make the magnums primers do it for a reason, they don't cost anymore, if they can't make more money on then why would they make them at all if they are not needed?