I loaded a batch of 257 AI's a while back using the WIN. WLR primers (new lot with gold cups). I went to the range and had 2 misfires. I took a few of the same lot of ammo antelope hunting last season and had another misfire which cost me a shot at a doe. I was getting very concerned that I had a bad lot of primers and asked around if anyone else had seen this same thing, nothing! I went to the store that I bought them from and they said they hadn't heard of the primers being bad either. Well, the other night I had an idea and decided to check the seating depth on the lot of ammo. Most of the primers were seated from .0045-.007" deep. I thought that optimal depth was around .002-.003". Could this be my problem or is it something else? Are the new gold cup primers softer and are getting crushed a little when seated (I use a LEE Auto Prime tool)? I loaded my first round of ammo when I was 16 and have over 20yrs. of loading experience, but this is the first time this has happened to me. I need to load a batch of 270 Win. and was planning to use this same lot of primers, but I don't want to load them and then have to take them apart if the primers are bad.

Thanks for the opinions,
Elk Country

Speer claims 0.003" - 0.005" as optimimal for their primers. I don`t remember where, but I`ve seen warnings also on chrushing the primer compound by trying to seat to deep and effectivly killing the primer. The pocket depth will have bearing on how deep of course but I think you may be straining the primeing pellet?
I doubt it is the WLRs. I`ve been loading scores of the newer gold plated ones for the last few years they have been out, and haven`t had a problem with them yet.

You primer depth is based on how deep your primer pocket is. It has no real relation to how deep it is below the head of the case, assuming its within reach of the firing pin. The primer has got to be seated to the bottem of the primer pocket, no matter how deep it is. If not, you get a "cushioned" firing pin strike where the firing pin pushes the primer to the bottem of the primer pocket. That movement absorbs the blow of the firing pin. You get a dimple on the primer and everything looks normal except the round didn't fire. Often, if you retry the round, it will fire.
I've never heard of seating a primer too deep will deaden it.

I wholeheartedly agree with 1wzbeeman. I seat primers to the bottom of the pocket and have never had one fail to fire because I "crushed" it. You'd really have to get medievil on them to damage them by hard seating. I had a number of CCI primers fail to fire in a .243 because I was trying not to seat them "too deep". After re-seating them, they all went off.

Not trying to be a smart ass, but were the cases charged with powder? I've had some "misfires" that would have fired just fine had the cases had powder in them.

Damn, Craigster, I thought I was the only one that did that.

It would seem that if your feel when seating the primers wasn't to fault, then the firing pin protrusion may be just a few thousands short = a misfire on occasion.

There is always a chance of systemic failure, see government if in doubt!

The SAAMI spec. for mass produced ammo is to have the primer 0.002" to 0.005" below the case head. RCBS even makes a go-no go gauge, or did at one time, that can be used to check it. I have this gauge and use it when I use certain kinds of primer seating techniques on large runs of ammo.

Federal likes to have 0.003" of crush on their primers. That is to seat a primer with a preload by getting the anvil exactly on the bottom of the primer pocket and then putting on 0.003" of a crush fit. I have a priming tool that will do this.

You can seat primers to just touch the bottom of the pocket, too, if that is what you like.

Still, you need to have the anvil firmly seated on the bottom of the primer pocket and you need to limit the amount of travel that the firing pin has to go. If the firing pin does not reach the primers well, then problems occur.

I have a .257 Roberts AI and I can state that at least part of your problem is the primer depth, but you may also have a little excessive headspace from the case forming process that adds to the distance the firing pin must travel. Be careful on case forming and make certain that you get a stiff enuff load so that your cases fully fill the chamber and then don't shorten them with your sizing dies, either.

Lastly, an overzealous primer pocket uniforming operation can get you into trouble. Try not to waste too much time primer pocket uniforming; it really pays very little for the amount of time put in, and deep primer pockets are a problem.

Randy -

Maybe I missed it, but what type of firearm was this in?