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I have the gages....I just chambered a rifle in that round and bought both the reamer and the gages both. What kind of falling block? They are my favorites. We might be able to work some kind of loan for you.
Steve

quote:

Originally posted by Grenadier:
I don't have headspace gauges for .450 3-1/4". Does anyone know of an expedient or alternate method to the check headspace on a falling block rifle. I'm not building a rifle. I just want to verify headspace is within acceptable limits before shooting one.

Since it's a rimmed round headspace is measured from the forward edge of the rim to the face of the block, with the block held back against it's support or locking surface.

What you want to do is determine how much of a gap there is between the head of a seated case and the face of the block. Under most circumstances, you can probably get by using a simple set of feeler guages.

For this to work, the case head needs to be flush or it needs to protrude slightly from the breech of the barrel. Begin inserting leafs between the case head and the block until the block will no longer ride up and lock into place. You probably don't want the gap to be greater than .004.