So I had nasty leading towards the muzzle along with keyholing and horrible accuracy in a new 9mm pistol barrel, using an alloy, bullet style, HiTek coating and load that had worked just fine in my other Glocks (confirmed by subsequently shooting the same lot of ammo through my other guns without any such problems).
So far I’ve found two potential barrel issues.
The first is just plain poor barrel machining. All my other barrels, both OFM and aftermarket, with polygonal or standard lands and grooves rifling, had a smooth, even mirror like internal finish. This barrel (reportedly a Glock factory “Marksman Barrel” from a third party vendor) has machine marks on the whole length of every land and groove, along with what to my inexperienced eye look like chatter marks as well.
The other is that I just did a preliminary slugging of the barrel in question, along with an after market Glock barrel with standard rifling (a BarSto) and an OFM polygonal barrel off a G34. The groove to groove diameter on the BarSto was 0.356” and the valley to valley diameter of the G34 was the same. The suspect barrel had a groove to groove diameter of 0.359”!!!
This is the first time I’ve encountered this type of problem. I will double and triple check the bore slugging, but are there other things I should consider? If not, is the 0.002” misfit (I cast 0.358” and size to 0.357” after coating) the most likely culprit?
And what to do? I’m a bit doubtful that I can coat up another thousandth with HiTek, and really don’t want to tinker with my 95-3-2 alloy and casting technique in order to cast “fat” (I’ve premade what I figure to be several years ‘ supply). Should I be in the market for a new barrel?