Large Pistol Primers for Large Rifle Primers?

[perdurabo]

I bought 10,000 Winchester Large Pistol primers (WLP) awhile back for reloading 45ACP and which I have a lot left of. Ive noticed that large rifle primers are exactly the same size as large pistol primers. What, if anything, is the difference? Why cant I use WLP primers for reloading large rifle cartridges like .308? Would it affect how I load the ammo in terms of potential pressure vs. using WLR primers?

[W.E.G.]

Thinner cup.

Pierced primers if you use them in high-intensity rifle catridges.

Probably OK for black powder loads, or reduced-charge lead bullet loads.

[Shootability]

Not exactly the same deal, but I once loaded up 100 .223 rounds with small pistol primers - I shot a few and had no problems with pierced primers, but the accuracy was less good - shot them over a chrony just for grins and found the SD was really high - I suspect they did not ignite the Varget as well.

I might try them in a bolt gun that has a good gas protection system like the Mauser, but I would not start out with heavy loads. Possibility of a slam fire occurs to me in an autoloader - perhaps better to trade them off for what you need.

[W.E.G.]

One other difference between rifle and pistol primers I just learned:
"large size rifle primers are taller than large pistol primers"
http://www.levergun.com/articles/454_case.htm

[ftierson]

Originally posted by perdurabo
I bought 10,000 Winchester Large Pistol primers (WLP) awhile back for reloading 45ACP and which I have a lot left of. Ive noticed that large rifle primers are exactly the same size as large pistol primers. What, if anything, is the difference? Why cant I use WLP primers for reloading large rifle cartridges like .308? Would it affect how I load the ammo in terms of potential pressure vs. using WLR primers?

The short answer is, "Don't do it..."

That's why they make both rifle and pistol primers. It mostly has to do with the pressures that the cartridges produce.

As a matter of fact, some high intensity pistol cartridges use small rifle primers (if they take small primers, of course)...

It's a bad idea to try using rifle primers in pistols (potentially resulting in misfires because of the weaker firing pin blow in many handguns compared to rifles), but it's an even worse idea trying to use pistol primers (designed for relatively low pressure) in high intensity rifle cartridges. In addition to the liklihood of pierced primers that Gary mentions is the much increased chance of slamfires in semiautos that solvability mentions...

Save the LP primers for pistol ammo...

Get LR primers for rifle ammo...

Forrest

[FAL4EVER]

Originally posted by W.E.G.
One other difference between rifle and pistol primers I just learned:
"large size rifle primers are taller than large pistol primers"
http://www.levergun.com/articles/454_case.htm

See also:
MRI BFR 500S&W warning (http://www.magnumresearch.com/news_detail.asp?story=bfr_warning.asp)

[BUFF]

The amount of priming compound (ignition material, or the "explosive" matter) in the two primers varies in quantity and formulation. The rifle primers have more and hotter as they are generally igniting a far bigger powder charge of slower powders that need the extra flame.

The rifle primers are also "taller." If you seat them properly in the wrong cases, the rifle's firing pin may or may not have enough reach to adequately crush the pistol primer's priming compound between the primer's cup and anvil, and the rifle primer may stick up above the face of the pistol cartridge's rim, leading to poor mechanical cycling and possible slam-fires.

The primer's metal cups are thinner in a pistol primer and may pierce and leak when used in a rifle, or be otherwise too weak after the firing pin strike to contain the higher pressures.

Don't do it. Your eyes are worth more than a million primers.