7MM-08 Ackley Go Gauge

[shortgrass]

If you get the chamber too short you'll feel it when trying to close the bolt on a 'parent cartridge', it'll take excess pressure on the bolt handle. It's a matter of 'feel' . Depth mic and GO gauge for the 'parent cartridge' have always been a successful method for me. Also, there can be a wide variation in new cases from manufacturer to manufacturer and from 'vintage', when they were made. There is no SAAMI spec on AI, except for the .280 AI.

 

[TylerFromMS]

I don’t know what SAAMI headspace gauge measures, but I did a wildcat based on a 7mm-08 AI and told them I needed a go gauge and they sent this. Maybe it’ll help:

 

[59FLH]

I don’t know what SAAMI headspace gauge measures, but I did a wildcat based on a 7mm-08 AI and told them I needed a go gauge and they sent this. Maybe it’ll help:

View attachment 1424452

Thanks

 

[ggshoots]

What you asked is exactly what I do. I like to use a standard Go-guage instead of fired brass just because I think it will be more durable if changing barrels out much. I shorten the go-guage actually crowding -.005 and can still chamber the parent case just fine. I will typically just put 2 layers of scotch tape on then to use as no-go guage, works fine. I have yet for a Ackley barrel to not shoot the parent cartridge extremely well and quite often better that the original chamber.

 

[std7mag]

I just use the go gauge to set it as the no-go.
Then check with a piece of virgin brass.
I'm feeling for the slight resistance when closing the bolt on the virgin brass.

If you can't feel it, you may have gone too deep.

You can load 1 round with the bullet set out to contact the lands. Loaded to a mid charge from a loading manual, you'll get enough pressure to fire form the shoulder properly, but won't (shouldn't) give an over pressure situation.

You can then use that fireformed case for measuring.