what recommended upgrades RO

i have plans in a future buy a Range officer(close to $1200.00 in Puerto Rico,ouch) and i want to know what is the most important upgrades to make this pistol more accurate. i want to know what is the best kart barrel(single or the kit).thanks

Trigger job. I did my own with an Ed Brown fixture for the sear. Other than that  mine is stock and it will put 10 in the 10 ring with most being x's of a sand bag at 50 yards. Not bad for a stock 1911!

A gunsmith fit barrel and gunsmith fit bushing will squeeze a bit more accuracy out of it.  Mine has a KKM barrel and EGW bushing.  The factory barrel could be welded up and re-fit but you're stuck with a chamber that is cut deeper than I prefer.  That's not to say the factory parts are bad...have seen a number of Range Officers that would easily hold the 10 ring at 50 yards right out of the box.  If you go with a Kart barrel, I would recommend the gunsmith fit barrel rather than the XACT fit barrel to ensure you get the tightest lockup.

Agree on the trigger job...out the box the trigger is a little heavy. 

The factory RO mainspring is also pretty heavy.  If you plan to shoot a 22 conversion like a Marvel or Nelson, I would recommend going with a 17 or 18 lb mainspring. 

Lastly, after getting on occasional light strike my gunsmith replaced the factory titanium firing pin with a steel one.  This cured the light strike issue.

http://www.brownells.com/handgun-parts/barrel-parts/barrels/1911-precision-quality-barrel-prod7615.aspx this barrel with kart bushing or EGW is better than kart bushing???

The Range Officer uses an unramped barrel...the Brownells part number for what you would need is 472-020-045WB (out of stock at the moment).  The fitting of the barrel and cutting the chamber for your ammo is where the accuracy gains will be realized.  Unless you plan to do this regularly, may be money well spent to have a gunsmith do the fit.

On bushings, the quality (accuracy) is also in the fit rather than the brand in my opinion.  I like using EGW because they will make one that's already angle-bored to the inner diameter and outer diameter of your specifications.  You'll need to measure your slide and barrel to determine the dimensions you need.  My method is to get a bushing with an OD of 0.001" less than the slide opening and an ID of 0.001" more than the barrel's diameter at the muzzle.  This gives me a fit with a clearance of about 0.0005" in any direction. 

Of note, if you just provide EGW your measurements, they will determine how much clearance to add which is more than I prefer for Bullseye guns so I always add a note in the Remarks that I've already allowed for clearance and request the bushing be cut to my specification with no additional clearance added.

Usually the made-to-order bushing is a snug fit in the slide...can push it in by hand and start the turn, then finish with a bushing wrench.  If the bushing to barrel fit is a little tight I use a cratex bit on the ID of the bushing and it usually goes with just a bit of polishing.