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As Texas10 said the retaining pin removes easy if you compress the ejector pin first. I use common nuts on all three sizes of bolt heads. Knock the corners off the nuts until they fit easily up to the bolt face. Squeeze the ejector an spring in a vise. Drive the pin out from the side opposite of the spotface.
My punch is turned down to .059/.060.

Shown in pictures: 10-24 nut for small rifle bolthead, 1/4-20 nut for std "308" head, & 5/16-18 nut for magnum head.

Learned this lesson long ago and ended up drilling out a retaining pin.
For what it's worth I use the same method on assembled bolts including Remington. I have the correct size "flat head" screw screwed in the side of my work bench. I use my stomach to compress the ejector, leaving both hands free for the punch & hammer.