Any particular purpose for the rifle?
The polygonals are overrated. I've shot the SR-9 TC w/ poly and a douglas barreled SR9TC with similar results for accuracy. The advantage that I've experienced is with the cleaning of the barrel.
If you are looking to build a bolt-gun tack-driver, I'd suggest going for a Cooper CPM barrel from Accuracy International. It's a button-rifled 5R barrel, similar to the Oberndorf 5R barrels being used for the PSG1s now. Contact George Gardner of GA Precision (816)221 - 1844 he's got both Accuracy International 5Rs in stock and he may even have the Oberndorf 5R available. He can turn them to any profile you need and chamber them for your specific caliber.
