Just my opinion, the range rods are a bit longer- gives you more length for error/correction?  Folks tell me how accurately they dialed a barrel in but their range rod fit .0015 loose, how can they get their runout within tenths then???
   
I use gage pins because I have them and use them for my business - each bore is slightly different.  Making sure there are no burrs and that a burr isn't raised when using a range rod or gage pin is a challenge few recognize.  (I can get on a soapbox here that will have a serious yawning affect to most).

We use sets ranging from .020 to .750 - plus sets and minus sets -so they'll fit to most any of the bores I fool with, way overkill for what's needed.   

If you're doing multiple barrels, get a set of minus gage pins.
My 2¢ and then some.
Greg

I agree with Greg. I have used range rods and the bushings seem a little loose. So I am back to my gage pin set.
kw

thank you for your answers. the reason I asked was because I do have Gage pins and do not have range rods. However, for the barrel that I want to thread and chamber a .450 is slightly loose and a .451 will not go in at all.

I like the feedback here and I have another bit of info, based on my experimenting so please take it for what it's worth - opinion based on a few experiments. 
 
To begin with, a friend of mine who apprenticed at G&H and then went out on his own and has an established business building high-end rifles, has asked me numerous times to thread and chamber rifles that have metric threads - his lathes are old American iron and don't give him the option of cutting these "darn" threads.  One of the first jobs I did for him sent him into a tailspin, using my gage pins for alignment.    He said it wasn't worth wasting time on this- his barrels were close enough ID to OD.  I've shot a few of his big boomers and if you can bear down and hold center, they shoot exceptionally well at the distance they are designed for.   
Now, in some of my own smaller bore rifles, sitting at a bench, shooting high power, exceptional glass, all the rigging to go with it, on a good day, I may be able to tell the difference at a 100 yds between a perfect chamber aligned barrel - and one that is skewed... I know a few shooters that can tell me there's an issue and I've been a witness to it. 
Then, a slow moving, large caliber that goes sub-sonic at 280 yards, throwing a cast bullet and tries to hit a target or gong at 1000 yards, that  chamber that runs out  .001 or .002 to the bore - few could probably couldn't tell any difference.   
In the schuetzen game it may show up slightly shooting off the bench, probably not if one is breech seating and definitely not noticeable in the offhand game.

S-P,
your situation is a case where having a set of -plus/and/or minus- gage pins would benefit.  Plus generally run .0002" larger and minus pins will run .0002 under... do they warrant having for this? - NO.  Your runout will be fine.
 
Bob,
In the case for the muzzle, I'll have slugged the bore 3 or 4 times finding the tightest spot, then cutting the barrel off at that point.  A gage pin that fits this close is preferred, and I'll slide it in and out the inch or so I have to work with, checking it at a couple points and then machine my crown. -close enough.  On the better barrels, I rarely notice any change.  Had a few that didn't cost as much and there are some questions raised.
I have a very nice B&S cylindrical grinder that will make absolutely wonderful gage pins but setting up and making them isn't very high on my list of priorities so I tend to use what comes in a box. 
5¢ worth 
Greg

Gage pins... Much needed in anyone's shop.



JMH

When I worked it the mold shop we had gauge pins for the coarser work and Deltronic pins for checking ejector and core pin holes when building a mold that would flash in .0002-.0003. I still have my two .000050 indicators. The shop was kept at a constant temperature year round. After grinding a detail on the surface grinder you had to let the part stabilize before inspecting it. Sure don't miss those days. I use an Inter-rapid .0001 indicator one each end of the bore and work directly off the lands and grooves.
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For those of you who only have two points that are running true then still having to clock your muzzles at either 6 or 12 o'clock when fitting the barrel to the action..
When I started creating the three points that were all now running dead true. What I found was that the muzzle would then stay running dead true. So I no longer had to then clock the muzzle when fitting the barrel to the action. I also chambered through the headstock and used a spider on the muzzle end. Once I had both ends of the barrel running true I would then go in ahead of throat and re-dial it in with the muzzle end so those two points were now running true. I would then taper bore the chamber to create that third point that would also now be running true with those other two. I would also use the same taper on the reamer and this would also keep the back of the reamer running dead true with the floating pilot. I would taper bore it to a depth that would also leave very little left for the reamer to still have to cut.