I have built 3 rifles for myself over the last 8 years, 2 of them Border cut rifled barrels one of which did not like 129 grn bullets the other loved anything you fed it. The current "death ray" has an 18 inch Archer barrel fitted and it deals with any and all it is fed with 100 grn. Hornady soft points giving a ragged hole which you can just get a 260 case through (5 rounds). I have re-barreled several other rifles of varying makes with Archer barrels with very good results from all of them. The 260 from my experience is one of the least fussy rounds to load for, I use Vit. 140 for 95, 100 and 107 grn. rounds and 160 for the heavier bullets, work from the Vit. manual and you will get good results. Some of my friends have moved up from 100grn. bullets because of larger exit holes on through chest shots on roe but I dont find them to be messy and I would rather have an exit which gives a good bleed in case you have to follow up, had a couple who remarked on well shot beasts running 20 to 30 yds. yes and you get the same with a 308 using 150,s. So how good is it, with 100grn. bullets, better than the .243 by miles and with 140,s a tiny bit under the .308 in effect but still a very seriously good round. Hope this helps you in some way towards a decision, when I built my first one it was a voyage of discovery but not a difficult one I have had 6.5 calibre rifles all my life on a variety of different cases my personal favourite the 6.5x55 and my idea was to use the 260 with 6.5x55 loads only in a short magazine/action rifle and it works. Good Luck
Brora 260