Magnum loads without Magnum primers?

[bearing01]

I've seen a couple of posts saying pressures are higher with magnum primers. I can see that as a plus...If you start working the load up, chances are you can reach your desired or max. velocity using less powder than with a non-magnum primer.

The way I understand it, to achieve max velocity you want a load that achieves the gun's (or ammo's standard) maximum pressure rating, but to achieve it [without exceeding it] with the largest possible powder load. That way there is more powder to burn and release energy at that peak pressure value for a longer duration - just to release the energy over a longer time period. That way the pressure isn't just a quick jolt to the bullet but rather a sustainable strong push behind the bullet for a longer duration. That long push while the bullet is in the barrel will keep pushing up the velocity until the bullet exits the mussel.

If you look in your load books at the velocity for the maximum loads (loads achieving max pressure rating), you'll see the loads using more powder typically give the highest velocities. When using faster burning powders with the same bullet you have to use smaller loads to not exceed that max pressure rating, and those loads typically have lower velocities because the burn duration is shorter.

I guess the magnum primers gives a better ignition to the powder, causing it to burn more rapidly. That make the powder burn more efficiently / quicker. But the problem is that the pressure hits the gun's limit more quicker - requiring you to back off the amount of powder. If you're using a really slow powder then I guess the magnum primer really helps start the fire.

 

[papajohn]

Pressure is what makes guns and bullets go bang, so it's a good thing, but like anything else, too much is rarely beneficial. Bearing01 is right........getting more pressure is good, but pressure spikes are not. The idea is to build pressure to a certain safe (but warm) level, then maintain that pressure consistently until the bullet leaves the barrel. You don't want the pressure to dip before the bullet leaves the barrel, nor do you want to burn half your powder charge outside the gun. The most efficient loads are those with semi-fast powders like Unique and AA#5, plus a dozen others. Using a magnum primer with easily-lit, fast burning powders is a bad idea, because it blows your pressure curve to flinders. Instead of a steady rise towards the peak, there is a sudden spike, which can cause (among other things) bullet deformation and erratic velocities.

Ballistic labs have sensitive pressure-testing equipment, that can accurately read the pressure curve. Regardless of how many theories I can come up with about powder burning characterists, I listen to what the labs tell me, because no matter what I think I think..........they KNOW. 8)

 

[WESHOOT2]

I have a 'significant' body of published data, and some of the 357 Magnum data is generated using Msagnum primers for all loads.

Check your data source(s) carefully.
THEN do what you want :shock:

I do.....

 

[bearing01]

I have since loaded some 357 Mag with blue dot. One load book said to use Mag primers and the other book called for standard ones. The tables in different books seem to have comparable powder weights. Because Blue-Dot is slower and tends to fill up the case, I'm going with the magnum primers on these. Maybe I'll load a few with the standard primers, just to compare the difference.

Update: I loaded 357 Mag with 125 grain JHP bullets and used both Alliant's Power Pistol and Blue Dot. I stepped up the charge from minimum to maximum. I used both CCI 550 Magnum primers and standard Remington 1-1/2 primers. I felt no observable recoil difference or accuracy difference in comparing cartridges with different primers. On a couple of the mid-range powder loads I did notice the Remington primers to bulge / crater a little while the CCI mag primers held up well. But then at slightly higher loads the Remington primers again looked okay. I don't know if the CCI primer cups are made from harder metal than Remington standard ones, I would imagine they are. But as far as going "bang" is concerned, Magnum primers will probably not add much performance if loading 357 Magnum with Blue Dot or Power Pistol.

 

[Rick Courtright]

Ballistic labs have sensitive pressure-testing equipment, that can accurately read the pressure curve. Regardless of how many theories I can come up with about powder burning characterists, I listen to what the labs tell me, because no matter what I think I think..........they KNOW. 8)

Hi, and welcome to the Forum!

Agreed all the way...

An uncle of mine spent his career making and testing solid rocket fuel. He told me it's essentially like gunpowder only for BIG "bullets", and they actually used shotshells for some of their initial testing of the models the computer generated.

He once warned me that no matter WHAT their past experience, AND the computer model, said, each new test was just that, a NEW test, and sometimes things went seriously wrong that weren't predictable at all. He was involved in an accident where the propellant they were using had acted in a perfectly linear fashion, and the models suggested it would continue to do so for a while. Unfortunately, nobody realized they'd already reached that crucial point when it spiked! It blew apart the test tank and he nearly lost his eyesight.

So, when I see people tell about "eyeballing" their loads and declaring them "safe" based on that observation, I often have to shake my head. And hope some of them never shoot next to ME...

Until I win the lottery and can afford all that neat testing equipment for myself, I, too, will defer to the guys who do this stuff for a living for MY advice!

Rick C