.284 Win shoulder bump question

[Quinc]

Bought some once fired Lapua 6.5x284 brass for my .284 Winchester Fclass rig. I expanded the necks and FL sized. Now I am trying to make them consistent and bump all of the shoulders back using the Redding bump die and I can't seem to get them below 1.806. I am using the Hornady shoulder gauge .420 and am hoping others who bump the shoulders on there .284 can tell me what they are bumping them to.

New Lapua 6.5x284 brass are measuring 1.800 +/- .005

 

[Larryh128]

Are you measuring to the datum line? Will they chamber?

 

[Erik Cortina]

You do not go by the print, go by what your chamber measures.
Bumping .002" back from fireformed brass is a good place to start. Make sure they chamber properly.

 

[Quinc]

I have not fired any brass yet with my rifle. The 6.5x284 fired brass I am not able to close the bolt. With the new lapua brass I am able to close the bolt with ease. I am thinking about just firing the new lapua brass without fl sizing or bumping and then starting from there.

 

[Laurie]

You do not go by the print, go by what your chamber measures.
Bumping .002" back from fireformed brass is a good place to start. Make sure they chamber properly.

Quinc

Yes +1 100% on what Erik says. Remember that Hornady, Sinclair etc gauges are meant to be used literally as comparators - ie you measure and compare fired / unsized brass from your rifle's chamber against newly sized examples out of the sizer die.

There have been views expressed on this forum in the past that such gauges should be truly that - a gauge that provides a true reading and could be used against the reamer drawing. Even if that were affordable and practical, the actual chamber is always marginally different from the nominal one on the drawing, and in any event different gunsmiths 'run the reamer into the barrel' slightly different amounts. One gunsmith I use always provides a marginally 'long' chamber by 0.002 or 0.003". So the 'headspace gauge' (it's not that, but we don't seem to have a more accurate name in general use) reading will be different for cases fired in a barrel this guy has put on from that produced by another 'smith with the exact same reamer.

As Larryh128 says - Do your resized / expanded cases chamber in the .284? That's the key starting point. I personally wouldn't want to use previously fired 6.5-284 brass for this application. There is a chance that you'll never get easy chambering or a good match with your .284 barrel the brass having been fireformed to somebody else's 6.5 chamber-shape.

 

[Laurie]

I am thinking about just firing the new lapua brass without fl sizing or bumping and then starting from there.
Sensible move

 

[nosualc]

Ignore the print you posted. It's only a reference, and for what you're trying to do is irrelevant.

The once fired brass is fireformed to somebody else's chamber.

If they don't fit in your chamber, you'll need to size them back until they chamber properly. Use your FL die.

New brass is usually quite undersized so that it will fit into any chamber within spec.

If you're using this in a f-class rifle, I'd skip the unknown quantity and start with new brass.

-nosualc