Jack V wrote:Your right In Military rifles free bore is not uncommon but this rifle is sold a precision long range rifle , free bore is not commo in that kind of rifle with the bullets they are chambered for but it's obvious the real description of this rifle is the Military one "Anti Material rifle " . Either way they do seem to shoot ok as others have shown but this one has a problem . Hopefully only the scope.
Crimps do not reduce chamber pressure they actually increase chamber pressure slightly by holding the bullet back longer as pressure rises , Crimp = higher neck tension = more pressure inside the case to make the bullet move out of the neck . A lot also depends on how hard the crimp actually is . The amounts involved are very slight as it don't take much extra to iron out a crimp .
Crimps can help accuracy but in most cases it's related to either straightening up the bullet in the neck or improving ignition and powder burn . Some boat tail bullets don't have much parallel section to seat on and even with good neck tension and seating dies can still have marginal grip they test fine in a concentricity gauge but after chambering can be out of whack . A crimp can help stop that from happening. Big calibres can benefit from a crimp even if it's just to stop recoil movement of the bullet when rounds are in a mag .
You have read it wrong or maybe it is a bit vague, I did not say they reduced chamber pressure, it was meant to read that crimps are a remedy when you are unable to seat to lands. i.e. to provide consistant start pressure as this is mainly all seating to the lands does. i.e. when the land s are too far away or when magazine length restricts this(my .300wm for instance.
I am well aware of what crimps do.
