I am shooting factory 150gr winchester power points in my 7mm stw and out of the last three boxes I have had 3 primers that have fallen out of the primer pockets or have been missing after I eject the shell. Is this dangerous and what causes this?

That is bad. If you're using factory ammo, inspect the chamber and bore or have a gunsmith do it for you. Possibilities include a rough throat, a tight neck, and extremely bad fouling at the beginning of the rifling. Less likely, the cartridges could be off; check their maker's web site for recall notices. If you have a chronograph, verify factory fps isn't being exceeded.

You might have terribly excessive head space.roger

agreed...this is serious and is likely a problem with your gun and not the ammo.....however it could be ammo as well

you need to find the problem before things get worse.

http://www.winchester.com/news/newsview.aspx?storyid=137 Recall of ammo in 7mm mag on the winchester web site. Search using the word Recall. This is not your ammo, but you should call winchester. Toll free nubmer is 1-866-423-5224 They may want you to return your ammo.

It is highly unlikely that this is a problem with your gun.

The ammunition is either generating excessive pressure (far above standards), or the case heads of this lot of brass are extremely soft. Either way, as others have advised, after checking your rifle for something obvious like a bore obstruction, by all means inform the ammunition manufacturer.

BTW: While most factory chambers for belted magnums have what I would consider "excessive headspace", this condition would not result in primers falling out of fired cases.

One thing I might add is that this is a new gun but it is a Blaser rifle and would not expect a rifle such as this to have a problem with it. It shoots groups that are touching and if there was something wrong with the gun I wouldn't expect it to shoot like this. Like I said before this has only happened a couple of times out of aprox. 100 shells. I shot a coyote the other day and when I bolted another shell the primer fell out and the shell didn't have one in it. I have noticed that putting new ones in when I reloaded these shells last night thast the pockets seemed loose.
I just don't know much about this stuff and don't know what to think.

I remember a post a couple years ago when the stw was still a little new. There was a guy ranting and raving about the super high velocity he was getting with win factory ammo.
HMMMMM....possible connection that there was some really hot ammo at one time??
One last comment...you don't clean your gun alot and leave oil in the barrel? This can cause high pressure too. I just loaded a guy some 3006 with 165 grain bullets and 57.0 of H4350. He shows up at my place with his BAR and the first one out the barrel clocks 2930---yeouch...I look at the brass...very flat primer.
The next one clocks 2830...and the next one and all thereafter clock 2730. Moral of story---oil is not slippery---at least when a high speed bullet is trying to "sqeegy" it's way down the barrel.

Stonecreek,

I'm sorry to absolutely contradict you, but this is a safety issue, and we have to ensure there's no misunderstanding.

Primers backing out is seldom high pressure, but more often low pressure in concert with a headspace problem. Among other sources, see Exterior Ballistics.

quote:

Backed-Out Primer: A primer which, upon firing, has been pushed slightly out from the primer pocket. Primers backing out generally indicates an excessive headspace situation, usually in conjunction with a light load. Can be caused by light loads alone, in some circumstances. Also referred to as a popped or protruded primer.

With factory rounds, this is most likely a rifle issue, not a load issue.

Jaywalker

Jaywalker: One of us doesn't understand Nube's symptoms.

I take what he describes (primer falling from pocket after firing and primer pocket too loose to retain a new primer) as definitive indications of primer pocket expansion, which is almost certainly caused by high pressure.

Excessive headspace DOES NOT result in primer pocket expansion, but rather in the primer backing part way out of the pocket upon firing (until it is compressed firmly against the bolt face). The phenomenon of "flattened" primers due to partial backout due to excessive headspace is very common and is often mistaken by the unititiated as the result of excessive pressure. Be this as it may, it is physically impossible for headspace to be excessive enough to allow a primer to back itself all the way out of the primer pocket.

The "DANGER" from excessive headspace is that, if the headspace is too great, the cartridge case may seperate just in front of the web ("head separation") upon firing. This almost never occurs, even with grossly excessive headspace on the first firing, but typically on a subsequent firing of the stretched and work-hardened case. Most actions handle the escaping gas from a separating head without damage or hazard to the shooter or the gun, but some do not and some shooters have received injuries from a head separation.

I agree that Nube may be at some risk from firing his rifle, but the risk appears to be associated with this particular ammunition rather than with "headspace".

Is winchester maxing out there powder in this case beyond what they should be then? I would think that they wouldn't have a hot load. I did shoot a few at a chronograph and had just over 3200 fps with 150gr bullet. This speed doesn't seem high for a 7mm stw but the shells that I did have the problem with were probably from different boxes and might have been overloaded by accident. I still don't know what to think and I guess if it happens when I shoot my reloaded shell there is a problem going on. Is there a chance that the brass had a flaw in them? All boxes of ammo were baught at the same time. Mabe it was a bad lot of brass?

quote:

Originally posted by nube:
I am shooting factory 150gr winchester power points in my 7mm stw and out of the last three boxes I have had 3 primers that have fallen out of the primer pockets or have been missing after I eject the shell. Is this dangerous and what causes this?

Are the 3 last boxes the same lot number? Your should do a search on google using this "accident blaser rifle" There was a recall on the trigger, and info on guns blowing up.

Stonecreek,

You are right that one of us doesn't quite understand the issue - it might even be me! Maybe more info can clarify it.

BTW, discussions that don't generate immediate flames are rare enough these days to warrant notice - so, thanks.

Jaywalker

Jawalker; Please explain how "low" pressure would expand the primer pocket?.
It's a chance for all of us to learn.
Good luck!

I don't believe low pressure would expand the head. What happens often if you have an excessive headspace and then fire a light load. The firing pin drives everything forward. The case expands to grab the walls. However there isn't enough pressure to expand and push the case back to the bolt face. The primer is then unsupported and will move back until it hits the bolt. Leaves you will a primer sticking out of the case. Normally just enough to see and feel. The primer pocket remains tight.