It's easy to do--once a primer is out of the package, there's no way to tell one from another.

Take them to the range and try one. Then check it for pressure signs (which will be described in the front of your loading manual). If it shows no pressure signs, try one or two more. If they are OK, then use them. If any show pressure signs, pull them apart and size them again.

I've found new primers can be pushed out almost like fired primers, with just a bit of extra care. Make sure you have eye protection and follow this procedure:

You should LOWER the decapping pin so the case is NOT pressed into the sizing die (you want SPACE between the sizing die body and the case so if the primer fires the pressure can exit the case mouth and go between the case and die body). Then lower the press handle slowly to gradually push the primer out.

TIP: If you are worried about detonation, stand to the side of your press. If the worst happens--the primer fires and zips out of the primer pocket, it's going to follow the channel in the ram and go straight out the front. If you are beside the press WITH EYE PROTECTION, this shouldn't pose a problem. Worst case is the primer might be doing the speed of BB fired from a Red Ryder (probably less than that, though).

Another TIP: Clean your press, especially the crap around the ram bearing surface (at the bottom of the ram), the slot in the ram where the old primers fall, and the shell holder. This stuff could blow around if the primer fires. It probably won't do much more than sand at the beach on a windy day, but that's enough to hurt the hell out of your eye.

If you have properly adjusted the decapping pin, you will have to decap and resize in two separate steps because the decapping pin will be so low that it will bottom out and bend on the case if you push the case up high enough to resize.

I've pushed out a number of live corrosive primers this way and never had one fire. But if one did I wouldn't care because I take these few precautions.

In the tests I have performed...not every possible load, but a sample...magnum primers did not increase pressure at all. Several others have reported the same result. Your individual results will vary.

The original claim of magnum primers was more consistent and reliable ignition of slow powders in cold weather.

If you don't feel like depriming a live primer, in spite of all the good advice from above, a drop of oil kills a primer pretty quickly. Leave for a couple of days...

Or, faster: chamber the primed case (no powder or bullet, please ) in your rifle. Put the muzzle against an old rag (it gets dirty), and fire the primer. The rag takes the gunk and noise out of the exercise. Your barrel will need an oily rag afterwards.
- mike

I've read that advice all my life. But not too long ago I saw a post by a guy who'd tested primers that were oiled and some wet down with water, too, and said that they fired!

I've done the careful, slow decapping routine with important body parts out of the line of "fire," also with a heavy rag wadded up underneath the ram where the primer would go.

But as has already been advised, I'd just load up those .270s and shoot them.

Pecos45 aka Todd E aka James Smith!!!

Pecos45 aka Todd E aka James Smith!!!