Anyone know the correct headspace gauge for a 35 Whelen improved ackley. I know you can use a 06 gauge but think there's a little more to it. I dont know if some outfit makes one just for the improved...Thanks Bill B

Use the -06 gage and chamber .004" shorter. This ensures a crush fit on the parent case for fireforming.

What I want to do is ckeck headspace on a old rifle. Every once in a while I have a case come apart just above the rim say quarter inch or a little more. Something is not just right the chamber looks ok so I thought ckeck headspace...

The 30-06 go gauge works as a no-go in an Ackley chamber. The bolt handle should not drop with the '06 gauge in the chamber.

If a case is "bumped back" more than necessary, and is fired and resized like this a number of times, it can lead to case seperation. That may be what is happening in the Whelen AI. There are different methods of determining how much the shoulder is being move when the case is run through the sizing die. The chamber may be within specs but the f.l. die is pushing the shoulder back a lot more than needed. Redding makes a set of 5 shellholders that are from .002 to .010 HIGHER than the standard shellholder. With those, you can hold the case back as much as .010 or as little as .002. This allows you to fine tune the amount of "bump" on the shoulder.

Thanks for the infol. I did ckeck headspace with 06 no go gauge and was ok. I'm thinking now it's the brass or how Im resizing them. Think will buy a box of 35Whelen shells and fireform them to my chamber and just neck size them and see if they still come apart.

I had the same problem of brass coming apart on a 35 Whelen AI. I was using commercial Remington 35 whelen brass fireformed. I switched to Lake City 30/06, match brass. I expanded the neck and then annealed the neck and sholder prior to fireforming with cream of wheat. I only neck size these rounds and have not had one of them fail since.

Bigbore,

You misread what M. Pursell said. Use a .30-06 go gage to test the AI chamber for no-go. Using the 06 nogo gage is more like using an AI field gage.

THe reason the AI headspacing is set minimum is to reduce the case stretch. It sounds like your chamber is on the long side.
If you oil the case when fire forming it will move back then fill forward into the
chamber. Then if you set your resizing die to just touch the shoulder your case
stretching will be minimized.
Good Luck!