I am new to reloading rifle cartridges. I currently need to reload .223, .270, 300 win mag, and possibly 30-06. Can I use one powder for all of them?

Maybe, but it wouldn't be ideal due to the burn rate requirement for those different cartridges.

ETA: Look through a reloading manual to see if they list a powder that covers the cartridges you want to load.

quick answer: not really optimally, but maybe


H4895, IMR 4895, Varget, and 4064 would probably be closest to being able to do all. That being said, each probably is giving up a bit in each cal (though I do like 4064 in 270). there are better ones in each to use, but they are versatile enough to be found in loading manuals for a variety of calibers, i think including those you listed.

check manuals, find something that works for you. I would probably split out the 270/30-06 (same parent cartridge), 223, and 300WM separately.

One powder for all wouldn't give you great performance in all of them. I
agree with MSUICEMAN's concept to lump the '06 and 270 together plus
I'd add the 300 WM in too as Win 760 powder is a good choice for all
three calibers.  I prefer ball powders over stick or flake because I load in a progressive press so H4895, IMR 4895, Varget, and 4064 wouldn't be my preference.  As a ball powder, Win 760 is a good choice for all three calibers because it's more accurate in the large cases than say, Win 748 (also a ball powder and a good choice for 150grn M1 Garand and M1A loads).  



This is because Win 760 was formulated for the large cases like the '06, 270, and 300WM so that you can fill them with more powder per round to gain higher velocities and achieve a higher case density. (Higher case density is one of the keys to higher accuracy in your loads. ) E.g., for a '06 with 150grn bullet, max load is 48grns of Win 748 vs 60grns of Win 760, however, Win 760 does produce some 160-180fps more velocities.  





Your .223 powder choice could then be H-335, BLC(2), or Win 748. That way you are down to only 2 powders.  Note:  Win 760 is not a good powder for shooting in a M1 Garand as
it's higher pressure curve can bend the op rod.  So, if your '06 is a
Garand, then I'd suggest H-335, BLC(2), or Win 748 for both the '06 and
the .223.  You're still at only 2 powders.






 
 
 
 

It wouldn't be optimal but it could probably be done.  H4895 would be a good start for researching load data.  It is pretty versatile.

Yes, probably you can but the "one powder approach" is not the way to do this.  Get the best powder you can for each cartridge.  That does not mean different powders for each but if you have to get a second powder, do it.

If you throw out the .223 it would be no big deal. Could you settle for 2 different powders?

Nope

I like what I've gotten with H1000 for .300 winmag,  H385 for .270 (might have the numbers mixed up) should work for 30-06 too, and TAC for .223

What is your reason for wanting one powder?  I am still fairly new to reloading as well, and once you start seeing how your charges effect the load you will want the best powder for the job.  At this point I would buy calibers based on powder, over finding a powder to work with all my calibers.

What manuals do you have?  

http://www.ar15.com/forums/t_6_42/416805_Suggested_Rifle_Powder_to_use____.html

I use H4895 for .223, 6.8, 30-06 & a couple of other calibers - nothing in the Win Mag type range though

IF you can source it nearby then also look at Vihtavuori - maybe N140