Match grade barrels are made to a much tighter tolerance, using a fine-grained, stress-relieved steel (frequently cryogenically treated, also) and have a finer bore finish.
You can't just buy a barrel and put it on, however..... the barrel bushing and barrel must be fitted to each other in order to gain any accuracy. Not properly fitting the two could actually render the piece inoperative, if there were enough interference to prevent it from going fully into battery.
Fitting a match-grade barrel to a 1911 is a job for a VERY good smith, or a return to the manufacturer.
You can't just buy a barrel and put it on, however..... the barrel bushing and barrel must be fitted to each other in order to gain any accuracy. Not properly fitting the two could actually render the piece inoperative, if there were enough interference to prevent it from going fully into battery.
Fitting a match-grade barrel to a 1911 is a job for a VERY good smith, or a return to the manufacturer.