Primer Question

[Kokanee]

Thanks for the input guys.

NO, I was not going to randomly swap primers and guess at charges.

In reading published recipes, I noticed that some called for 209's and some called for 209A's and the 209A's used less powder.
Just seemed like it was smart to use 209A's and the published recipe for that load.

[LynnJr]

So you use the same amount of powder in regular primer loads as magnum primer loads -.^

From speer #10
Magnum Primers

Magnum primers contain a greater amount and/or slightly different explosive mix than is used in standard primers. On ignition, magnum primers give longer burning, hotter flames. Their use is recommended for (1) any ammunition that will be used at or below zero degrees F., (2) with most Ball powders and (3) with slow burning rifle powders like MRP and IMR 4831 in very large cases. Magnum pistol primers often will give more uniform velocities in magnum handgun cartridges loaded with large charges or slow powders like 296, 2400 and H-110. Magnum primers may be used with faster burning or easy-to-ignite powders, but normally there will be no advantage in doing so. As when changing other components, it is advisable to reduce powder charge weights on initial loading with magnum primers.

While I completely understand that you can use magnum primers in any load what so ever, it would be stupid to use load data for regular primers and then insert a magnum primer.

There are some use cases with slower burning powder that it does make sense but again the generic advise is to drop .5 to 1 gran if using magnum powder.

CCI Primers in ft lbs

small pistol 5.5
small rifle 6.0
small rifle magnum 7.2
small pistol magnum 8.8


My point is you don't mix load data from mag load data with regular load data. Pressures can be different.

also from the CCI website

http://www.cci-ammunition.com/products/primers/primers.aspx?id=29

"Usage Note: Use Magnum primers only where
called for in published reloading data"

Same message in Speer Reloading manual # 12 on page 38.

Same message in Lyman 48th edition on page 23, 32
also "
Do not use magnum primers unless the data
specifically calls for these as doing so can alter ballistic
uniformity and the safety of the data. "

and on page 95

"Particularly if you go from a standard to a
magnum primer. However, reduce your powder charge
5% if you do because the magnum primers will cause a
jump in pressure."

on page 99

"Anytime you change something in your load, the
pressure can change. Something as small as a primer
change can send the pressure over the safe limit. This
is particularly true if you switch from a standard
primer to a magnum primer."


Can you point me to a source that says they can be interchanged without modifying load data, specifically in applications that do not call for a Magnum primer and powders that do not call for magnum primers? Any at all?



the switch to magnum primers also has other factors like cold temperatures, ball, vs flake, fast, vs slow primers. Load data is NOT interchangeable between these. If you can find me a published source indicating you can switch these without modifying load data, then direct me to it so I can learn more.




I will say this.Use what is called for in the load data. 5 or even 10% may not be much to some but if you figure COAL is reduced, running max powder and you switch to a magnum primer. That could certainly put you in a danger zone.

Actually switching to a magnum primer is a tuning option. The manufacturers publish there manuals for ALL reloaders many of which have no common sense so they error on the side of caution.
If you COAL changes and you switch to a magnum primer and you have no experience with the load common sense would dictate you work up your load from the beginning.
Once you have some first hand experience your chronograph numbers will let you know if your getting close to pressure problems.

[Chaosh1]

For 12G I use the following using a Mec 9000:

Remington STS Hulls.

Down range XL1

17.6 grains of 700X

Cheddite Primers

1oz eagle shot.

[zapatito92]

Only use mag primers for ma. Loads.

Use the primer for the intended purpose. Rifle and mag primers have more of a charge and can be dangerous if you mix them.

Look at the primer box and it will say pistol shot gun or rifle or magnum loads

I too am just starting to get my feet wet, but this is for sure

[Marshal Sixgun]

Once you have some first hand experience your chronograph numbers will let you know if your getting close to pressure problems.

Could you please explain how chrono numbers indicate pressure problems? I've never heard that and I'd like to learn. Thank you.

[tonyjr]

A chrono gives you the speed of bullet . More pressure = more speed . To much speed and a lead bullet leaves more lead in barrel and can spin apart in air .
To much pressure can / will weaken barrel and most bolts .

[NapalmCheese]

Could you please explain how chrono numbers indicate pressure problems? I've never heard that and I'd like to learn. Thank you.

To paraphrase John Barsness:

If the load is listed as a certain velocity at a certain pressure in a 24 inch barrel, and you attain that velocity in a 22 inch barrel, your running at higher pressure than the listed load.

Also to paraphrase Barsness:
Your gun won't blow up the first time you go above SAAMI max pressure, but if you keep doing it your gun will eventually let go.

[Marshal Sixgun]

To paraphrase John Barsness:

If the load is listed as a certain velocity at a certain pressure in a 24 inch barrel, and you attain that velocity in a 22 inch barrel, your running at higher pressure than the listed load.

Also to paraphrase Barsness:
Your gun won't blow up the first time you go above SAAMI max pressure, but if you keep doing it your gun will eventually let go.

Thank you! I think I get it. For the same powder of course. Burn rates can achieve more or less velocity with different pressure curves, right? Or is pressure really a matter of just mass times velocity for a given barrel length?

[tonyjr]

Burn rate is just one factor .
Powder type [ ball / flake / extruded ] , bullet type - powder coated [ not any the same , different company / different coating ]
Lead cast - again not the same - from hard lead to soft
Plated - again not the same - different company / different plating
Even the FMJ some companies use softer copper than others .
Then you get to crimp
Next is the case - nickel or brass - both crimp different and release bullet differently .
That is why you start with factory info - try it and change one thing at a time
This is one reason most of us buy bullets 500 or more at a time .
I buy primers by the brick [ 1000 ] powder by the pound [ others buy 4 or 8 pounds at a time ] While I don't , others sore their cases by head stamp / name

[NapalmCheese]

Thank you! I think I get it. For the same powder of course. Burn rates can achieve more or less velocity with different pressure curves, right? Or is pressure really a matter of just mass times velocity for a given barrel length?

The super simplified version is that burn rate determines how quickly a certain volume of gas is generated. That volume of gas in comparison to the volume of container that gas is held in determines pressure. A small container (the chamber and barrel) with a small leak (the muzzle after the bullet exits) that suddenly has lots of gas attempt to decompress within in a short period of time will see higher pressure than a small container with a small leak that had a lot of gas attempt to decompress in it over a longer period of time.

Internal ballistics is complicated.

The reality is that bore diameter, bullet weight, powder charge, bullet type, barrel length and plenty of other things go into determining the pressure generated and the appropriate powders.