07-10-2013, 07:14 PM
For HSS reamers, which are usually best and cut smoothest when the number of barrels are lower, I would always recommend Manson Precision Reamers. They make fine Grendel reamers and on some occasions even have them as a stock reamer. Do opt for the live pilot though if chambering a good barrel as the fixed pilot can mark the lands as it turns.
I would think that the chamber is too tight especially if PTG say they have no margin on the tolerance. The tooling is essentially out of specification just as soon as it has settled in. This is a good practice for bench rest gun but not for an AR. The Grendel is frequently misunderstood and those chasing accuracy will tighten head space and also the neck diameter and neck length. The cartridge is intrinsically accurate and while the effects may be realized in a specialized bolt action this is not the case with the cartridge in the AR. The gas port abnormality in the rifling has a greater effect. We also see the chamber concentricity is important but that the crown is surprisingly tolerant.
I would think that the chamber is too tight especially if PTG say they have no margin on the tolerance. The tooling is essentially out of specification just as soon as it has settled in. This is a good practice for bench rest gun but not for an AR. The Grendel is frequently misunderstood and those chasing accuracy will tighten head space and also the neck diameter and neck length. The cartridge is intrinsically accurate and while the effects may be realized in a specialized bolt action this is not the case with the cartridge in the AR. The gas port abnormality in the rifling has a greater effect. We also see the chamber concentricity is important but that the crown is surprisingly tolerant.