Question: AR22LR Barrel Dimensions

Hi! I recently joined the forum as this appears to be where the best content is!

I searched the forum and didn't find anything (or my search skills are lacking).

I picked up a 22LR barrel blank from Green Mountain and I'm working with a local machinist to chamber and profile it for a dedicated AR22LR build with a CMMG dedicated bolt (not a conversion kit with a chamber adapter).

The part I haven't been able to find, what are the dimensions of the chamber end of the barrel (from the barrel extension shoulder and back)? Hopefully that makes sense, if not, here's a picture of what I'm struggling to find, dimensions inside the blue box. Specifically, the dimensions of the "nipple" that interfaces with the dedicated bolt collar.



Does anyone have a drawing I can reference or a link to point me in the right direction?

Thanks!

I should think that CMMG should be able to provide this if they are selling the bolt/bolt carrier that interfaces with it. Is there any info in the doc that comes with the dedicated bolt collar?

I did a few I’ll look and see if I can find my notes
Get with your shop first , your gonna want to make a dummy barrel extension and thread the rear of the barrel into it rather than trying to machine it onto the back of the barrel as cmmg does.
FYI my green mountain stainless blank I used for that project hammers, I used a Benz chamber
However make sure you slug both ends of the blank to find the smaller end and make that the muzzle
The end stamped on mine was actually the smaller end

I've got 1.665 from the flange on the breech extension to the back of the adapter.

I measured one yesterday, but got tied up and forgot to post the dimensions. I’ll try to dig them up tomorrow when I’m back in the shop.

I do remember the “nipple” length was very tough to measure and I kept getting different measurements, but I’m betting the length is .700”+/-. There’s a groove on it for a detent, that my measurements will be rough.