i recently purchased a 223 ack imp barrel for my savage mod 12 223. i have headspace gauges, but am getting varied opinions as to how to install the barrel..i am being told to insert a standarn 223 brass and apply a crush on that brass, then back barrell off a little..any help appreciated

A properly headspsced Ackley chamber should be a crush fit on the parent case. I realize that the term "crush fit" is not a highly accurate measuring procedure but it should work for your application. Is your headspace gauge an Ackley or standard 223? If it is an Ackley you're good to go. Dave Kiff at Pacific Tool and Gauge will send you an Ackley go gauge.

thanks eddie,
i have go/nogo gauges furnished by adams and bennet, the manufactuers of the new barrel. however, i am being told that i want to allow a fired 223 round to completely fill the new chamber when form firing and that i should use the 223 parent case rather than the improved gauges....

Curtis

Headspacing with Ackley Improved chambers is easy once you understand the concept.

When you insert a standard .223 case in an improved chamber, the only part of the case supported by the chamber in front is a thin line at the neck/shoulder junction. If you have normal headspace, the firing pin will drive the case forward crushing the case at the neck/shoulder junction. There by forming a case that is too short for the chamber or better known as excessive headspace.

To prevent this from happening you set the chamber up with a negative .004 inch headspace. That way when you close the bolt the case is crushed forward as far as it can go and the firing pin can not shove it forward any farther. Thereby creating a case with zero headspace.

You can accomplish this minus .004 inch headspace two ways. You can use a new case to establish zero headspace condition then turn the barrel in .004 inch more ( with Savage barrel threads at 20 tpi ) will equal 30 degrees. Tighten the lock ring.

Or if you have Ack Imp H S guages you can simply screw the barrel up against the go guage and tighten the lock ring. The Ack Imp guages already have the minus .004 inch H S factored in.

thanks craftsman..that certainly make the most sense..if ifollow the headspace gauge instructions sent with the barrel, i should be in fine shape as far as safety and accuracy goes???

If your go guage is for the Ack Imp 223 then you can safely proceed. Set it up for zero, dont back off.