Difference between Large Pistol and Large Rifle Primers


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Zerstoerer
April 11, 2009, 03:43 PM
Let's say someone (who can't believe he has just done that) loaded some 30-30 WIN cases with large Pistol versus large Rifle Primers.
What's the difference anyway? They do fit...

Safe to shoot or time for the unloading hammer?
Thanks.

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GRIZ22
April 11, 2009, 03:58 PM
Rifle primers are designed to withstand more presssure. With that being said the SAAMI chart I looked at showed 42K for the 30-30 and 36K for the 44 magnum. If you're loading hot loads (not a good idea to exceed pressures a case wasn't designed for) I'd say pull them. If moderate loads you'll probably be okay.

I use LP primers in a reduced 30-30 lead bullet load but the pressure on this load is about 18K according to the Lyman manual.

Zerstoerer
April 11, 2009, 04:04 PM
Rem case, 35.0 grs of IMR 4064 with a 110 gr HDY RN bullet for an advertised 2400 fps.
Too hot?

GRIZ22
April 11, 2009, 08:08 PM
Sounds like a mild load. If you try it be sure to wear eye protection in case you blow a primer.

BUGUDY
April 11, 2009, 10:06 PM
I asked this question before, and the answer , or a answer, is that large rifle primers are taller than large pistol primers. The rifle primer pocket is a bit deeper, ?". so a large pistol primer in a rifle, sets a little deeper, maybe too deep, but a rifle primer in a pistol could cause a slam fire.

Hummer70
April 11, 2009, 11:01 PM
There is another difference and that is cup thickness between rifle and pistol primers.
Handguns by and large don't have the ability to deliver the energy/velocity required to ignite rifle primers thusly the cups are thinner and the energy required is about 55% of what is required for rifle primers.
Cups being thinner may or may not sucessfully hold the pressures generated in rifles.

I just had a interesting situation. I got a new Remington 7615 and upon firing noted the primer wanted to crawl up inside the striker opening. I just happened to notice the 100 pack primer box I used said Small Magnum Pistol but the 1000 sleeve clearly said Small Rifle. I went back to the master case of 5000. It was marked small pistol but the 1000 sleeves inside said Small Rifle. I called the vendor and confirmed the color code on the primers was in fact small mag pistol and I had to remark all my sleeves.

When I switched to small rifle milspec primers I noted the same condition to a lesser extent and a check of the striker energy (described below) was conducted and I had a .016" indent. Subsequently I obtained a high energy spring from Wolff, changed it out and am now getting just shy of .024" indent and no more reverse primer flow.

What do these figures mean in the big picture? I will try to explain.

Striker energy is measured on coppers which is the exact same coppers used to determine chamber pressure but used in a different fixture resembling a headspace gage except there is a round hole where the primer would be about .375" deep with a flat bottom. It is called a "copper holder" and the copper cylinder is placed in the holder and placed in the weapon and muzzle pointed towards the floor so that the holder will be supported by a solid surface be it in the area under the rim or the belt (magnum rifle) shelf or the shoulder of the chamber.

Once this is done the hammer is cocked and trigger pulled. Obviously the striker moves forward and strikes the copper leaving a indent known as "copper indent"

Primers are designed to work at a very small window of energy supplied by the striker and weapon systems are speced for a minimum copper indent requirement to insure reliable ignition under all circumstances.

For instance a 38 Special has a minimum energy requirement of .009" copper indent. 357 Magnum has a requirement of .011" copper indent as the mag primer is a bit thicker to handle the higher pressures.

Small Rifle primers come in two variations as well. Standard small rifle and Milspec Small Rifle. The new industry standard is .016" indent on copper where some vendors still retain the old standard of .020". The M16 spec requires .022" indent for the milspec primers.

Large Rifle primers are much the same. .016" being new standard with old standard being .020" indent.

I try to keep my rifles set up delivering in excess of .020" and have several that deliver .024".

I have copper holders for 5.56, 7.62 and 30.06 and a good supply of the coppers.

Primer testing consists of several areas and are tested with drop fixtures wherein a steel ball is released from a given height and impacts a striker in a fixture holding a primer.

There are no hard and fast rules for all calibers so lets just say the spec calls for a all fire drop height of 20 inches with a steel ball weighing two ounces.

As long as it is dropped from this height it will continue to ignite the primer but lets say the ball height is reduced to 19, then 18, then 17 inches. Obviously the energy striking the fixture will be lower and slower.

Now the all fire height lets say is .012" copper indent which happens to be the all fire drop height of most large rifle primers. As the energy or velocity is lowered you will start to get periodic misfires of say 1 in 1000, lower the drop height a bit and you may get 10 in 1000, lower it again and you may get 100 in 1000 and so forth until the other end of the window is reached and you determine the all no fire height which happens to be .009" copper energy in large rifle primers.
Note: the indent seen on a fired case is absolutely meaningless.
Note: the allowable misfire rate on US primers is one in one MILLION.

Now I mentioned velocity. It is possible to obtain a .020" copper indent and never fire a primer. How? Simple raising the ball weight to 20 ounces and drop it from only two inches. You have the same energy but not enough velocity to achieve ignition.

Copper holders last I bought about ten years back are about $165.00 and the coppers are very expensive and very very hard to find.

There are ways to insure you have enough striker energy on some designs but not all. If anyone is interested I can expand on it.

Coltdriver
April 12, 2009, 10:31 AM
The difference is in the thickness of the primer cup. You will probably pierce a primer with pistol primers in a rifle. I wouldn't even try one out. Just break em down and reload them right.

Zerstoerer
April 13, 2009, 02:18 AM
Thanks to all - Hummer 70 - wow, you learn something new every day.
So my mistake made me learn a lot about primers. Thanks.

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