.223 Go Gauge for A.I.

[centershot]

Seems like a dumb question, but since A.I. headspace on the shoulder junction, can a standard .223 Remington Go Gauge be used for a Ackley Improved?

 

[AckleymanII]

Yes

You need a crush fit on a new case as headspace can vary .006-.010 or more on new cases, depending on the brand.

For my own guns, I use a new case, and I have chambered my own guns with as much as -.025 crush fit(22/250 AI's).

So, in order to never have any case stretching on fire forming, have a crush fit where you HAVE to bump the shoulder just a tad to get a new case to chamber. Keep the lugs lubed on your bolt, as you want firm contact with the shoulder when you are fire forming.

This is of course an advanced way of setting up an Ackley Improved Case or any case for that matter.
The practice of jamming the lands to keep the case against the bolt face is REALLY bad thinking as the firing pin drives the bullet in the case deeper(if you seat the bullet out far enough to "soft seat"), and you will end up with various headspace lengths on your cases with some cases having some "stretch" which may or may not leade to premature case head separations some 25 or more firings down the road, (non lubed cases).

To check your chamber set up with an AI go gauge, take a new unfired parent case, smoke the shoulder neck junction with a candle, cigarette lighter, match and carefully chamber it. When you examine the extracted shell, you should see a bright ring around the shoulder neck junction indicating contact in the chamber. In fact, you may "feel" contact with the shoulder on the very bottom of the bolt closing. Problem is that new brass will vary in headspace length, more or less with different brands of brass as quality varies, this is where Lapua brass really shows it's quality as it is very uniform.

So, what happens if you happen to buy a rifle that is an AI and there is no contact on the shoulder with new brass? You are forced into a situation where fire forming with Cream of Wheat and Bullseye are not an option, you have to use a bullet seated out long to jam the lands hard, and you want to feel some resistance in closing the bolt or firm contact. Also, lubing the cases would ensure that the case did not "grip" the chamber walls up in the front end of the chamber, then stretch to meet the bolt face. This is NOT the best way to go in setting up an AI case, and when PO Ackley set up his cases, he had marketing to take into consideration in selling the whole idea of being able to shoot factory ammo.

 

[centershot]

Guess I should have stated this woud be a pre chambered Shilen barrel on a Savage.

 

[AckleymanII]

Terry, tell him how.

 

[JRS]

The standard GO becomes the NO-GO for the Ackley.

 

[DaveTooley]

It's not as simple as yes. If the neck diameter is changed then the intersection of the neck/shoulder junction of the chamber will change on a standard 223 gage. The larger the neck diameter the contact point will be further out on the shoulder of the gage making a shorter chamber. Likewise if the neck is smaller then the contact will be closer to the neck/shoulder junction making a longer chamber. As a smith I use AI gages because I have some calibers with many different neck diameters. That insures chambers of a consistent depth regardless of neck diameter.

 

[AckleymanII]

Guess I should have stated this woud be a pre chambered Shilen barrel on a Savage.

OH CRAP!!!

 

[mpickle]

The standard GO becomes the NO-GO for the Ackley.

It really is that simple. The standard GO gauge becomes the NO-GO gauge when cutting the AI chamber. That way the factory round will chamber with "feel". That tells you that the case is tight against the front of the chamber and is maintaining headspace. Ackley Improved chambers, when properly cut, are safe to fire factory ammo. Ackley designed them that way. Ergo, the standard go gauge becomes the no-go gauge. It is really that simple,,,Am I repeating myself?
Mpickle

 

[Geno C]

I know this bothers ackleyman because he likes his shorter, but, my jgs print actually states "223rem GO -.004" headspace".

 

[Dusty Stevens]

I know this bothers ackleyman because he likes his shorter, but, my jgs print actually states "223rem GO -.004" headspace".

Thats where the crush on a sized case comes in. Thats exactly where he is

 

[Geno C]

Exactly. I just meant that ackleyman likes quite a bit more crush to make sure even short factory brass is tight

 

[Dusty Stevens]

Thats right. Like me hes been down that road of stretching the web area

 

[GrocMax]

Keep in mind the datum point for the AI is not in the middle of the shoulder, its at the neck/shoulder junction. A 223AI go gauge will still have the 23 degree shoulder, its just .004" shorter, thus the issue with tighter/looser neck diameters.

In my ignorance of the AI standard I sat and waited around for a 223AI go gauge to hit the shelves thru normal retail channels, should have just ordered a std 223 go and shortened it .004".