I have a Dan Wesson Valkyrie, I've never gotten into 1911s enough to know the difference between the 6,7,8 round mags.  My gun came with 8 round mags, but many websites say the gun comes with 7 round mags.  What height differences are there in the mags?  How do I know if i'm buying the right size for my gun?  Mine is the 4.25".
                                      Thanks,
                                                  Woody

7 and 8 have the same body, just the 8s use a different follower to squeeze in a extra round. The 6 is for officers model frame sizes. A 7 or 8 should work in any of the frames. I carry a RIA version of the officers model with a flat bottom 6 in the mag well and a pair of 8s as backup ammo.

The 1911 was initially designed to be used with a 7 round magazine.



8 became common, and is used with the Wilson 47D magazines.  You can get them with or without slam pads. I prefer the slam pad because mag changes are easier when the magazine doesn't sit completely flush.



Chip McCormick makes a very nice 10 round, which I often carry as a spare. It sticks out a little bit.


Personally, I carry an 8 round Wilson in the weapon with a a Chip Power 10 in my mag pouch.

As Willie stated, 6rnds are for officers models.

there are 7 rounders for the officers model, but they are usually marked officers model.

The Wilson 8rd mags are great,  I buy and use them.  

However, the 8rd Chip McCormick Power Mags perform even a little better than the Wilsons for me (I've shot a lot or rounds through either in USPSA and practice and these two mags are used a lot by other such shooters).  

And the Power Mags are cheaper.  So I recommend and use preferentially, the 8rd Chip McCormick Power Mags:


Nevermind.  It looks like your gun is an officer framed model:  



You really should look that up and understand what it means.  Is your gun 45ACP, or 9mm?  I see it comes in both.  

Did not know that!

Came to help give knowledge and ended up recieving some!

Be aware that not all guns like all magazines. My two main full-size 1911's run fine on wilson 7- and 10-rounders in their "47" series, but not on wilson 8-rounders. Lot of people swear by the wilson 8-rounders, but neither of my full size guns like them at all. Personally, I like the checkmate 7-rounders, and I believe those are what wilson sells as their 'service' 7-round magazines.

Point being, it would be a good idea to determine what your gun likes, before stocking up on a bunch of any particular magazine.

The Valkyrie is an officer's ACP sized frame, under a commander length slide and barrel assembly.
With that, you can use magazines common to pistols like the Colt New Agent and Defender, older Officer's ACPs and compact model Springfield Armory, etc.
Factory capacity for that length magazine was 6, and Wilson Combat and others have made follower changes that allow 7 rounds in the same length magazine body.
Wilson also offers a modified floorplate for their government length 7 and 8 round magazines, that will prevent over-insertion into the Officer's ACP-sized pistol magazine well
(Right: Government model length 8 rd WC 47DCB)



(Middle: OACP-length Wilson Combat 7 round 47OXCB)



(Left: Gov't length modified for OACP Wilson 8 round 47DOXB)
   

 
 

 

The RIA came with two of them.

This is a fair amount of information to take in before making a decision to buy a bunch of mags.  The gun comes stock with 2 Checkmate 8 round mags.  I'm over 1000 rounds in a month and a half with the gun and I haven't had a single malfunction.  This includes an assortment of standard pressure and +P hollow points.  I can buy mags direct from checkmate, would it make the most sense to just get 8 round identical mags from them, or is it worth trying out different manufacturers?  

I own a lot of plastic guns, and a few revolvers, where this idea of what magazine to get hasn't really come up for me before.  

Does anyone have a link that goes over all the basic ins and outs of what constitutes an Officer size vs whatever else and so on?

http://m1911.org/full_history.htm

This site also goes over 1911-A1 vs 1911 differences.

When I carry my Colt Commander, I carry an 8 round McCormick in the gun and two Wilson 10's in the belt.

Chip McCormick 8 rd with base pad.

Is that what you carry in an officer size frame? Or just for a reload?

I often use g17 in my g19 and m9mags in my m9a1 compact_with no prproblem. Do 1911s have problems with longer mags "over inserting"?

The Wilson 10 rounders have a metal stud welded to the front of the magazine to prevent that.

7 round magazines are the only type I will use. The top round is less likely to slam into the feed/barrel ramp. It gives the spring more room to work. And Browning obviously designed the gun that way for a reason. I only use hybrid feed lip magazines with a Wolff 11# spring. USGI follower with dimple is also what I use. These followers will not wear at the slide stop shelf like a nylon follower, like the Wilson 47 can have issues with. It also has a dimple to control the last round feed. I believe Wilson now uses a follower with a dimple, and Tripp has one on theirs, albeit a bit far back.

This ensures positive lockback, smooth feeding with a variety of bullet types, and cartridge lengths, and a long service life for the spring.

That said, the hybrid style feed lips will spread quicker. I rotate magazines yearly. I use the Wilson Combat Service Mag Plus. It's manufactured by Checkmate, which is the OEM supplier for Colt. It's basically the Colt 7rd mag but stainless.

At this point in time, I will not use any other 1911 magazine.

Ditto.