7mm Wby Barrel Ordering - Headspace and Chamber Protrusion

[KRP]

Chamber protrusion.... that amount of the chamber that is not contained in the barrel. IIRC the headspace measurement on a rimmed mag is approx. .221 and the figure you were given was .135 so...... .221 - .135 = .086 which is the amount of the cartridge that will be outside the chamber to allow for the extractor to get into the extractor groove.

hope that helps!

The belt is contained. The .135 is what a go gage will protrude from the barrel, which is about what the rim/extractor groove are plus a little bit(and some extra) for clearance between the bolt head/barrel. Factory bolt heads usually have ~.110 recess from the front to the face but they vary. With pre-fits they have to consider loose factory tolerances and add a bit of protrusion to make sure they will fit all rifles without bolt head/barrel interference issues since they aren't measuring the actual bolt face being used and chambering accordingly.

[loudandproud]

The belt is contained. The .135 is what a go gage will protrude from the barrel, which is about what the rim/extractor groove are plus a little bit(and some extra) for clearance between the bolt head/barrel. Factory bolt heads usually have ~.110 recess from the front to the face but they vary. With pre-fits they have to consider loose factory tolerances and add a bit of protrusion to make sure they will fit all rifles without bolt head/barrel interference issues since they aren't measuring the actual bolt face being used and chambering accordingly.

Ok, so the belt is contained by a relief in the end of the barrel. Headspace is considered the distance between the face on this relief and the bolt face. Chamber protrusion is set by moving this relief deeper or shallower in the chamber. Chamber protrusion does not affect the distance between the chamber shoulder and the face that the belt sits on.

^^All this sound right?

How accurate should I expect the chamber to be size wise... from the belt shoulder to the shoulder?

Has anyone here ordered a barrel in a belted magnum... did .135" work?

[KRP]

Ok, so the belt is contained by a relief in the end of the barrel. Headspace is considered the distance between the face on this relief and the bolt face. Chamber protrusion is set by moving this relief deeper or shallower in the chamber. Chamber protrusion does not affect the distance between the chamber shoulder and the face that the belt sits on.

^^All this sound right?

Yes, pretty much. The belt relief is part of the chamber, protrusion is a matter of running the reamer in deeper/shallower. Headspace is the dimension from bolt face to the forward edge of the belt relief. The distance from the belt to the shoulder is a fixed dimension per the reamer.

How accurate should I expect the chamber to be size wise... from the belt shoulder to the shoulder?

Has anyone here ordered a barrel in a belted magnum... did .135" work?

I'd expect it to be accurate to SAAMI specs, unless you specify differently. LW is a German company though so maybe CIP specs.

I've never ordered a barrel for a belted mag. You could measure your bolt head and brass and order to fit. It seems as if LW is offering semi-custom chambering to fit your rifle/components.