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If I have the 'smith re-orient the barrel by rotating it 90 degrees, how much set back would that be on the small Mark V action?

Don't know the TPI of your rifle, but if it is 16TPI in would be .0156 for 1/4 turn.
Divide your TPI into 1" and divide by 4 to get your answer.

Thanks. I found the original barrel. Weatherby uses 18 threads per inch. At that amount I may not have him redo the chamber. The longer neck would be a benefit anyway. It would be about .014" set back.

well you're still going to have to fix the head space. .014" will be way to tight

KLStottlemyer,

That is a good thought. And I already gave it some. Since it is a wildcat and the only one of its kind, I decided to run the hydro-forming die down .014" and trim that same amount off the full length sizing die. The load might change from 71.0 grains to 70.0 or something like that. But maybe it won't make any difference.

Are you sure it's 18 TPI? Weatherby Mark V rifles use 16 TPI.

You lost me with If the only thing done is trim the shoulder and bolt clearance area of the barrel the neck will be exactly the same.

If this is a belted round it will need the chamber recut for sure.

HiredGun,

This is a Mark V six six lug action. It is a wildcat on a 9.3X64 case necked to 6.5mm and blown out. According to the thread gauge in my tap and die set it matches the 18TPI. As far as the neck being longer, it would be .014" longer because I would re-chamber. The neck would be that much longer on the brass when I hydro-form the case.

If the tennon is .875" it is 18 tpi. It sounded like you were reinstalling an existing barrel and might have been looking to clock up the external marks to make it look right. With a rechamber you can make it anyway you want.

HiredGun,

This was a rebarrel job. It ran out of adjustment when I bore sighted it so I switched to Burris Signatures. In the rear I used a +20 in one side and a -20 in the other to get it working. I figured if the 'smith took off .014" from the shoulder it would required about 90 degrees more to tighten it against the receiver. It might change the side problem to an up or down problem.

I will pick up the rifle this afternoon. He wouldn't do what I requested.