substituting magnum for regular primers?

[wileynet]

of course every box of small rifle primers is gone, but still a lot of magnum small rifle, need to load some 204 and 223 rounds can these be used interchangebly

[revbc]

Should be fine as long as your not on the bleeding edge of a max load.  You may not get the same groups.  Probably won't.  Back off to the starting load and work it up.  You should find a good group in there.

[Lloyd Smale]

back off 2 or 3 grains and edge up carefully. Ive seen it make a differnce and seen it not. thing is the smaller the case the more sensitive to primer strenght it will be.

[stimpylu32]

of course every box of small rifle primers is gone, but still a lot of magnum small rifle, need to load some 204 and 223 rounds can these be used interchangebly

Short answer , NO , like Lloyd said , the smaller the case the more affect your primer will have , I have personally seen speeds of over 150 fps difference on my Chrono with the same load and MAG primers , best to back off and work up again , sorry buddy . 
 
stimpy

[BBF]

 The other possibility is using pistol primers, again not a problem unless you are right at top presssures.

[SHOOTALL]

some types of powder work well with mag primers others do not . might want to check it out first.

[roper]

of course every box of small rifle primers is gone, but still a lot of magnum small rifle, need to load some 204 and 223 rounds can these be used interchangebly

lot depends on who's primer your using here some on the Wolf small rifle mag primers

http://wideners.com/itemdetail.cfm?item_id=7283

If it's the CCI call them best way

[Center Shot]

I would try small pistol first these are more like benchrest rifle prlmers I use them exclusivly in the 22 hornet.