Hello, guys, I have a problem with my 243 loads....,the primerpockets expanded so much, the primers are loose in the action.
No other signs of pressure. Never had that before.
The loads are: Federal cases.
Sierra 100 Gr.Pro Hunter.
Kemira N 160. 42 Gr.
Federal L.R mag. primers.
Could the last component cause the problem? Otherwise it should be a moderate load.
Thank you for any input.
Hugh.

It might be the magnum primers as you infer that is different. But I like magnum primers but I don't use them in the .243W (yet).

I would measure the neck wall thickness. I have read where this can be a problem with the .243W in particular. And measure all the way to the bottom of the neck too. I have seen restricted necks at the neck/shoulder junction.

But everything is suspect. Is the powder correct or mixed?, are the bullets the right ones?, are these cases new to you?, Are the bullets jammed into the lands?

I am not sure what Keimura N160 is but if it's Vihtavuori N160 then my manual shows 45.3 gr as the max load.

I've shot 243's for going on 30 years and the only problem I've ever had was with federal brass. I have over the years sorted out and tossed all my federal cases. win. rem. or even necked down .308 and I have had good luck with mil. brass. Try a different brand and stay away from the mag. primers.

I have heard that Federal .308 cases are bad for having loose primer pockets after only a couple of loadings. It would stand to reason that the .243's, being of the same basic case type, may have the same problem.

Go with Winchester cases. I see no reason for a magnum primer in the load you are using, though I doubt that is causing your problem.

green 788

There is (according to quickload) a fast lot of N160 (allthough VV denied it when I asked them)

My own experience of 243 VV loads is that they seem a touch hot and this is borne out by talking to a professional rifle builder. VV loads for modern rounds are perhaps hotter than most manafacturers. Add together a powder that may have a large lot to lot variation, a cartridge that seems inordinately pressure sensitive (at least in my rifle and from folklore too) and a mag primer and I am not surprised. Throw in some other factor like seating to the lands, some warm weather and a rifle that has fired 50 rounds instead of the 10 that you pressure tested with and hey presto the primer falls out into the rifles action when you eject the fired case.

this may be dumb but i figure if winchester put there name on it they would no how to make the brass or same with the 6mm id think remington would no what there doing. i got winchester and laupa brass for my 243. just something that poped in my head one day
jason

As Don suggests, thick neck walls can cause pressure problems, but you would probably feel significant resistance when closing the bolt if this is the problem.

I tend to agree with 1894 that a misbranded, or "off" lot of powder might be to blame. These escape the factory on occasion (a recent problem with Alliant RL 22 comes to mind).

It is also possible that you have a lot of brass with a very soft head, although I doubt this. If it was originally factory loaded and soft enough to expand with the load you are using, it would have probably exhibited loose primer pockets after the factory round was fired.

I prefer "standard" force primers in all my loadings, even in large cases with very slow powders, but the pressure difference caused by "magnum" primers in your .243 is not the problem.

I'm going to go a bit off the wall here. A few years ago, a writer named Roy Smith had serious problems with a .243. He was loading with, IIRC, IMR-4350. being conservative he started a couple of graind below the starting load. Primers blew, as described above. Re reduced the load a bit more and had an even worse problem with pressure.
What I'm getting at is he ran into that strange but real problem of S.E.E., or Secondary Explosion Effect.
Now I have no idea where Kemira N 160 loads start or max out, but if he is near the starting load, and reducing it still causes problems, I'd look at S.E.E. as one possibility. BTW. Mr. Smith's problems went away when he increased his powder charges closer to the listed max.
Like I said, it's off the wall, but no one else has mentioned this as a possibility.
Paul B.

S.E.E. seems only to occur when significant empty space is left in the case. 42 grains of N160 would be filled to near the shoulder, so I don't think it would be S.E.E. Also, S.E.E. usually occurs with only SOME shots of identically loaded ammunition, and usually generates much higher peak pressures than would merely enlarge the primer pockets.

Good thought, Paul, but I don't think that the problem Hugh is experiencing is S.E.E.

Hugh,

Try some Winchester cases, and change nothing else. Let us know if that cures your problem.

green 788

Thanks for your efford guys,I'll take every advise in consideration, but I don't believe it is SEE, because the load is between starting and maximum load.An old VV manual shows 42.5 Grain at 3600 bar,wich is max allowed pressure in 243.I previous messured the same load at factory ballistics,so it should not be a hot one, no pressure sings than. It was in a Ruger,now it is in a Blaser 83,but I can't see the problem with that. Anyway: thanks a lot!
Hugh.

You sure don't need magnum primers in 243 cartrdge. They can cause a huge jump in pressure. Standard large rifle primers are the norm for the 243. Get rid of those cases with faulty primer pockets nad replace that brass with new. If you would read your reloading manual it would have told you the recomended primers to use for the 243.

Hows the length of the brass? Does it need trimming?

The lenght of the brass is ok.
Hugh.