CCI 300 vice CCI 350 Primers

[2Guns]

Will using a magnum primer (cci 350) significantly effect cartridge performance?  Is it safe to switch, use the same load except standard vice magnum primers or vice versa?

I have two reloading manuals that list similar loads for a .44 Mag, but on says to use cci 300 large pistol primers and one lists cci 350 large magnum pistol primers.

Would be it be correct in stating that the magnum primer just has a hotter and longer lasting ignition so it will reliably ignite larger quanities of powder?

[Questor]

There will be a difference in pressure. In general, don't substitute magnum primers for standard primers.  In the case of .44 Magnum, Speer retested Alliant 2400 powder for its latest manual and found that they got better performance and lower pressure with the standard (300) primer than with the magnum (350) primer that they had been recommending.  

In general, use magnum primers for ball powders like H110 and Win 296.  Heck, just find a load in a reputable manual and use their load data.

[Bullseye]

That is a tricky question.  As Questor stated, Speer has changed a lot of their data.  I switched primers because of their data in my 44 Mag and 41 Mag with IMR 4227 powder and my POI moved a bunch and my group size became terrible.  I had to go back to Magnum primers.  I have also always used Magnum Primer in a 22 Hornet with IMR 4227.  Got to thinking that this was not a good idea and switched.  I am know back to Magnums because my groups opened up terrible in it also.

Now throw in the fact that some brands of standard primers are as hot as other brands of magnum primers.

Now throw in the fact that some will say that by the time high pressure signs occur you could be way overloaded.

As you can tell I do not have the answer.  It is best to just load what the book says.  If you veer from that path, pay close attention to what you are doing.

[Gregory]

Whenever you change any component, be it primer, bullet, powder, or brass, start from the bottom and work up.

[Robert]

Gregory made it short and sweet and to the point.

[Redhawk1]

I use the standard large pistol primers for 45 L/C and 44 MAG down and the Large Pistol Magnum for the 500MAG. One the 2400 ignites well with the standard primers.