To break in or not

[Smellydog]

I thought you were locked out .....

 

[Cloudhopper]

A factory lapped barrel blank has yet to be chambered by the rifle smith . once the reamer goes in it will create some king of burr , its impossible not to by the action of cutting .
its is this burr that's removed by " running in". actually talk to the guys who are at the top of the game and you will be told the procedure they prefer .
A lot of Smiths take the guns to proof so they can themselves at least clean before each shot in proof.
Does breaking in produce a more accurate rifle ? well you wont turn the shooter who produces 1" at 100 into a 1/4" guy
does it extend barrel life ? no way to prove or disprove it !
Personally I do run a new rifle in always have, like i say if you don't you cannot go back but you also cannot go forwards saying it does not improve future cleaning or future accuracy and bore life

If it's a factory-manufactured, cold hammer forged barrel, is the mandrel a one-piece part for both barrel and chamber?
CH

 

[Bowland blades]

If it's a factory-manufactured, cold hammer forged barrel, is the mandrel a one-piece part for both barrel and chamber?
CH

Genrally speaking a 223 blank will be generic off the rack then chambered . One reason you get none concentric or larger /smaller chambers but yes it can also be done in one as you mention

 

[paultap]

I would definitely clean the barrel of a new rifle before it’s first firing, I have had several brand new rifles which having come from the proof house here in the UK, with dirty barrels. It seems to be too much of a chore for the proof house to even run a dry patch down the barrel after firing.

Personally I doubt it really makes that much difference, if any, by following a so called break in procedure.