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Substituting mag primers for std primers during shortage.
- Thread starter Brutus
- Start date
Yes it is, but we generally download our powder charge by about .3 of a grain of powder or more, when using magnum primers over what it would be with standard primers.
Some magnum primers have a larger drop of priming compound in the primer cup and some just have a thicker cup. Some may use a mix with a higher brisance.
But we don't know who is doing what in the primer industry so we err on the side of caution and just download a little.
For the most part, they don't want to divulge their trade secrets so we just don't know.
Some magnum primers have a larger drop of priming compound in the primer cup and some just have a thicker cup. Some may use a mix with a higher brisance.
But we don't know who is doing what in the primer industry so we err on the side of caution and just download a little.
For the most part, they don't want to divulge their trade secrets so we just don't know.
Average Joe
New member
I've done it, no noticeable difference in any of my guns
Substitute magnum for standard primers might give you increased pressures.
Magnum primers have nothing to do with how much powder is used. They are about the powder, but if you change any one component you really should start over and work up the load again not just reduce by .3 of a grain. That doesn't do much of anything.
Oh and the use of magnum primers has nothing whatever to do with the cartridge name like Hodgdon's site indicates.
Magnum primers have nothing to do with how much powder is used. They are about the powder, but if you change any one component you really should start over and work up the load again not just reduce by .3 of a grain. That doesn't do much of anything.
Oh and the use of magnum primers has nothing whatever to do with the cartridge name like Hodgdon's site indicates.
armoredman
New member
I will find out soon, as I switch from Rem 1.5 to 5.5 soon. Of course most of what I am loading right now is cast lead powder coated low velocity training stuff, so I think I will be fine on the load, but I'll load some testers first, of course.
Magnum primers can, indeed, affect how much powder is uses in some instances. In 223 Rem, for example, some magnum primers can cause you to bring powder charge down as much as 5% to match muzzle velocity. In the short automatic pistol cartridges, they can unseat the bullet before the powder burn starts, ironically causing you to need a larger powder charge to match a velocity. They can also cause poor ignition consistency in small powder space cases by sometimes getting the bullet out ahead of the powder burn and sometimes not. This will show up on your chronograph as increased velocity spread.
Cases are called "magnum" because they have more capacity than more standard cases in the same cartridge class do. Magnum primers are designed to make a larger quantity of gas for the starting pressure of the powder because powder needs a minimum of pressure to initiate burning and raise the pressure in a repeatable way. Indeed, too little can lead to loads squibbing out. So, recognizing larger (magnum) cases would need more gas to pressurize them for consistent burning, magnum primers were developed.
What the above fails to consider is that not all magnum cases that take the same size primer have the same case volume. lf I have a 357 Magnum case and a 32 H&R Magnum case, there isn't going to be the same need for extra starting pressure in the smaller round. So, the bottom line is, whatever the intent of the primer designer, you have to test for yourself with your powder in your cartridge to see which one better produces a desired velocity and has the most consistent ignition (usually indicated by lower velocity standard deviation).
This is a worthwhile read.
Cases are called "magnum" because they have more capacity than more standard cases in the same cartridge class do. Magnum primers are designed to make a larger quantity of gas for the starting pressure of the powder because powder needs a minimum of pressure to initiate burning and raise the pressure in a repeatable way. Indeed, too little can lead to loads squibbing out. So, recognizing larger (magnum) cases would need more gas to pressurize them for consistent burning, magnum primers were developed.
What the above fails to consider is that not all magnum cases that take the same size primer have the same case volume. lf I have a 357 Magnum case and a 32 H&R Magnum case, there isn't going to be the same need for extra starting pressure in the smaller round. So, the bottom line is, whatever the intent of the primer designer, you have to test for yourself with your powder in your cartridge to see which one better produces a desired velocity and has the most consistent ignition (usually indicated by lower velocity standard deviation).
This is a worthwhile read.
I in fact am starting down that path with a know good load testing directly with same powder level with magnum powder.
The load is no where near max so a possible shift would only throw me out of an accuracy node not be a danger.
The first test was interesting but not conclusive. Accuracy was almost as good, conditions for testing sucked (20 deg, a bit of wind). I was so excited to go shooting (well that changed) I forgot to get my insulated pants on (yes I did have pants)
The non magnum group was a gorgeous 1/4 inch in 5 shots. 1/2 inch with all 5 (still not bad and close to the 3/8 this load delivers when I do)
The magnum was also a 1/4 x 4 and then a wilder one for 5 shots at 3/4 inch.
As I and my hands were freezing at that point I gave up and will resume the tests next week when its warmer or I dress up right.
The load is no where near max so a possible shift would only throw me out of an accuracy node not be a danger.
The first test was interesting but not conclusive. Accuracy was almost as good, conditions for testing sucked (20 deg, a bit of wind). I was so excited to go shooting (well that changed) I forgot to get my insulated pants on (yes I did have pants)
The non magnum group was a gorgeous 1/4 inch in 5 shots. 1/2 inch with all 5 (still not bad and close to the 3/8 this load delivers when I do)
The magnum was also a 1/4 x 4 and then a wilder one for 5 shots at 3/4 inch.
As I and my hands were freezing at that point I gave up and will resume the tests next week when its warmer or I dress up right.
I switched to smp primers for 9mm when the spp supply dried up. A .2 gn reduction in charge works well with Unique but with Tightgroup it is too hot. Felt recoil is still less with Tightgroup, but I was getting residue in the barrel from the poly coated bullets. The residue is much harder to get off then lead. I had to scrub with a bore brush and JB Bore Cleaning Compound.
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If you follow the link in my post #9, you'll learn there is no standard approach to making magnum primers. They all make more gas, but some are higher brisance than others, some have long flame sustain, etc. So it is easier to do as JKP suggests with some primer brands than others. My rule of thumb for small rifle is to knock the load down 5% when changing primers, as that seems to cover the range of difference fairly well. I haven't done that yet for small handgun primers, so I would fall back to the 10% reduction until you know what you've got.
Use your chronograph to look for a change in velocity and not exceed the velocity you got with the other primer. If velocity goes up, then your pressure went up, too, and you want to back the load down.
Use your chronograph to look for a change in velocity and not exceed the velocity you got with the other primer. If velocity goes up, then your pressure went up, too, and you want to back the load down.
Magnum primers have nothing to do with how much powder is used. They are about the powder, but if you change any one component you really should start over and work up the load again not just reduce by .3 of a grain. That doesn't do much of anything.
Oh and the use of magnum primers has nothing whatever to do with the cartridge name like Hodgdon's site indicates
Oh, so your telling me if the OP loads maximum load of Clays in his 38 SPL, and substitutes a magnum primer for a standard primer, that it won't hurt a thing?
All the fast burning powders that are spiky at the top end with a standard primer are perfectly safe to use magnum primers with?
BS!
I have experimented with primers during load development and agree with what Uncle Nick said. When changing primers be it from standard to magnum or between brands or from standard to benchrest you should drop down and recheck. When I tested some Peterson SRP .260 brass I found that the BR4's and Remington 7.5's produced higher velocities than the CCI 450's. Also CCI 400's higher than Federal Blue or Gold box.
Bottom line is use common sense
Bottom line is use common sense