Question about No-G0 gage interchangeability

[tarheellin]

I'm changing barrels from a 7mm-08 to a 22-250 AI. I'm new at this, so I took ya'lls advice, played safe and ordered Go, No-Go gages for head spacing the barrel.

Well, I got the Go gage, but the No-Go gage had to be back ordered. So, I thought I'd cut my wait time by e-mailing the manufacturer to see if they had one on the shelf.

The manufacturer answered me very promptly. And, suggested that If I had head space gages for a standard 22-250, I could use the 22-250 "Go gage" as a "No-Go gage" for the 22-250 AI. ??? Or, I could call and they would send me one.

All the headspace gage interchangeability charts I've seen have the 22-250 AI requiring "unique" gages. The word "unique" sorta' "means one of a kind". Now, the gage maker is telling me different.

I'm green at this, dumb as a rock. ??? Would/ could you tool maker guys help me out with this ?... Thanks.

Lin.

[sinman]

It is ok to use a 22-250 go gauge as a no go for the AI version.

[sharpshooter]

Use a piece of sized brass from your 22-250AI full length die to set the headspace. You can check the clearance with red plasti-gage.

[savageboy]

How about a .308 Go gage as the NO GO for a 260AI???

Thanks,

Bob

[tarheellin]

Thanks for the responses... I am just getting all the tools, dies and gages together. I do not, yet, have any 22-250AI fire-formed brass to work with. I still have to load 22-250 and fire-form for the AI. So, I have to work with gages for my initial AI set up.

Sinman, I see you agree with the gage process. Would you help me understand the application ? If I understand correctly, the gages reference off the case datum line in the barrel chamber. For the 22-250, the datum is at 1.515", and the case dia. at the datum is 0.414. For the AI application, the datum is at 1.524 and case dia. at the datum is 0.454 (based on loading manuals).

So, looking at numbers, it looks like the 22-250 gage would be just wobbling around in the AI chamber without picking up reference at the datum line... No references except at the base after the AI chamber is reamed out. Where am I missing the thought process for the 22-250 Go gage to be relevant to the AI as a No-Go gage?... I told you, man, I'm dumb as a rock...

[sinman]

http://www.4-dproducts.com/faq_4d.php#faq12

[tarheellin]

Allrightie, then... Thanks for the link, Sinman.

So... Use a Go gage for AI to reference off the datum. But, for No-Go gage, you use a Go gage from the parent case because what it does is reference off the forward edge of the rim (doesn't care about the reamed out chamber clearance).

I'll chew on it ... 'til I get more experience than Mr. Ackley ;D ;D.

Thanks all... My back-ordered, 22-250 AI, No-Go gage has just been shipped... Can't wait to see what it looks like...