Switching to Large Rifle Magnum Primers

[Rol Page]

After having visited three large sporting goods stores with reloading supplies in NY and PA out of necessity I have had to change from using Federal Large Rifle Primers to Large Rifle Magnum Primers for my .270 Winchester and new 30-06 that I will be loading for shortly.  I purchased the Federal Large Rifle Magnum Match Primers, (GM215M).
I realize that I will have to be careful and back off the powder a bit to compensate for the magnum primers.  Does any one have any experience as to how much to back off?
Nosler and Sierra Tech's will be called tomorrow for their advice.
Thanks in advance for any suggestions.

[mechanic]

You need to "begin at the beginning" just as you would with an intial work up of a load.  I've been using the magnums since the last shortage, and the difference with some powders / loads is un-noticeable, with others it's significant.
 
Ben

[Ranger99]

 ^ ^ ^ ^ ^ ^ ^
i'd go with this above here.
they used to say back off 10%
but there are too many variables
to suit me.
you only get one set of eyeballs.
good luck

[zero]

I've heard on average the pressure is only increased if you had went up a grain? Or something like that. Probly more or less depending on the powder. Even if there's no increase in pressure with a load it could be a whole different ballpark in grouping though, so even then it's still better to work back up

I used to just use them in my 7mag, but here lately i've been starting to prefer them in larger cases like the 30-06 and 45-70. I get alot more reliable ignition with some loads

[Lloyd Smale]

just use starting loads in a manual and work up slowly and youll be fine.

[corbanzo]

I've done this with quite a few "non-mag" recommended cartridges, especially when loading ball powders.  They are usually fine within standard loadings.


I did have some nice over-pressure signs under a good dose of H414 in my -06, but if you start slow everything should be fine. 

[Siskiyou]

I have used Magnum primers while reloading surplus 4831 and commerical H4831.  I started low and worked up without an issue.