OK Guys,

The well known builder of 300/221 stuff tells me that my 16" SS heavy barrel and adjustable gas block has been shipped. Will probably arrive Monday ... my luck isn't good enough for it to get here on Saturday!

I do not own a set of headspace gauges for a 221 Fireball. I do have a set of gauges for .223. I have checked the assembled FA BCG I intend to use in the 300/221 (hereafter called "Whisper" simply because it easier to type) in an M4 upper known to work and which checks properly with military gauges. (closes on GO but not on NOGO or FIELD)

The BCG for the Whisper gauges just like the BCG known to work with live .223 ammo in the M4.

I have made 500+ cases for the Whisper. The whole pile of brass was cut to 1.356" +- 0.001" About 150 pieces of brass have been necked by sizing them in an FL die ... BUT the die was adjusted with 0.025" of feeler gauge between the bottom of the die and the shell holder. This should potentially make the cases just a little long to the shoulder.

I asked the maker to do me an ammo gauge with the barrel. I'll move the shoulder down a little bit at a time until the bolt closes and check the case in the ammo gauge.

When the brass just fits, I'll move move the shoulder down another 0.002" to give ammo the slightest bit of jiggle room and note the setup for future reference. As I am using a Corbin swaging press for reloading this cartridge initially I should be able to reproduce it nicely.

Now ... the question ... I would think going through all of this should pretty well assure I have a rifle that is headspaced properly and ammo that is not too short. Did I miss anything that could cause problems?

Thanks!

Mike

Nope looks like you covered it pretty well, but I would suggest when you get to the point where the cases chamber making up 10 rounds to do a function test before you settle on that setting for good.