Gunsmithing .223 Ackley chambers?

[Just Jim]

Hello all, I would be grateful for some guidance-

I have a Stiller Tac-30 action, Krieger 8-twist barrel, PTG reamer and "go" gauge, all in readiness for a .223 Ackley Improved build. I have heard from various sources that the chamber should perhaps be cut .003 to .004 below normal headspace to assist in keeping .223 Remington cases snug against the boltface when fire forming. What say you?

I have respect for the good folks at PTG, and wonder if their "go" gauge may already be configured for this short chamber approach, or, is such a chamber not required.

I would be grateful to hear your experience.

Cheers... Jim

 

[GasLight]

Re: .223 Ackley chambers?

My bad, I just read an article stating what you just wrote, that you want to short chamber for ackley improved, not something I have heard of before, it is just to fire form initially. I personally would still chamber to the go gauge and aim for .000" headspace. You do indeed want to keep the case head firmly against the bolt face while fire-forming, but that can be accomplished in other ways than short chambering the rifle. At the end of the day, the chamber is going to be a wildcat, so you will be able to control all the other variables during the reloading process after you initially fire-form brass to that specific chamber.

Dave

 

[Just Jim]

Re: .223 Ackley chambers?

Yes, that's what I've been seeing is the idea of cutting the chamber just short of the normal "go" gauge. In other words, below minimum headspace. Of course, how you might measure this, I have not yet puzzled out.

I try to cut chambers so that there is very light drag on the gauge after the barrel is torqued. Perhaps that will be sufficient?

Jim...

 

[GasLight]

Re: .223 Ackley chambers?

The article I read said you need a custom gauge ground. I guess I can see it making a little bit of sense, you don't want it loose enough where you are getting much case head stretch on your initial fire-forming if you are shooting factory ammo. If you are going to be reloading your fire-forming loads, then you can skin the cat in a different way...

 

[BillCh]

Re: .223 Ackley chambers?

Just Jim,
Is it that you want your AI chamber shorter than the 'standard' AI chamber by .330-.004?

When I did my .223 AI I bought both a .223 AI go and no-go gauge from PT&G along with my .223 AI reamer. If I recall correctly the AI reamer will cut around .003 to .004 short of standard .223 anyway. That is part of the AI design theory as I understood it from Dave at PT&G. This allows for a slight crush fit on a standard case at the neck-shoulder junction.

It all worked out as planned. I can feel slight resistance when I chamber a virgin case. The fire forming process goes without complications. It's pretty much a slam dunk deal.

You may just want to double check with PT&G that you have the correct gauge.

B

 

[areaone]

Re: .223 Ackley chambers?

Not sure how my chamber was cut. I am in the process of fireforming and finding the "right" load, Varget with 69 SMK
seem to be the ones. I am fireforming with 55 gr jammed, if not I am not getting the primers to fire(pushing case forward without ignition) jamming litely is the answer for my chamber. I am using Winchester brass with .250 neck, too tight for Lapua, unless I turn it, NOT. You will like that 223 AI

 

[Just Jim]

Re: .223 Ackley chambers?

Thanks to all for sharing your thoughts and experience!

BillCH, given your experience, I don't think I'm going to have any problems.

I'll cut the chamber to "just" accept the PTG "go" gauge, then try chambering a selection of new cases and factory ammunition and see if I get the slight crush fit I think may be necessary. If not, I'll cut the barrel back one thread length and leave the chamber just a wee bit shorter.

Thanks again!

Cheers... Jim...

 

[SDWhirlwind]

Re: .223 Ackley chambers?

Are your headspace guages for an AI or for a standard 223?? If for a standard 223 then your go guage would be the NO GO on an AI. If they are indeed ground for an AI chamber than just use the guages like you would chambering any barrel. Like you stated I would cut it to barely close on the go. Always easier to cut a thousandths or two later if necessary.

 

[Just Jim]

Re: .223 Ackley chambers?

SDWhirlwind-

Yes, .223 AI reamer and "go" gauge.

Yup, I have enough grey hair to have finally learned you can always remove more material, but it's darn hard to but it back on!

Thanks... Jim

 

[Bugholes]

Re: .223 Ackley chambers?

223AI GO gauge should be .003 or .004 shorter than 223Rem GO gauge. as previously mentioned, the purpose is to have a little crush ont he neck/shoulder junction to support the case and fireform correctly. Considering how exacting it is to get the correct "feel" to closing the bolt on a gauge or cartridge, you should consider the following:

headspacing to the "feel" on a AI GO gauge in the lathe can be problematic. You will likely need to do go + .001" with your gauge as the headspacing tool
-there will be additional shortening of headspace when the barrel is torqued on the barrel
-I always have customers send 5-10 pieces of the brass they intend to use <span style="font-style: italic">so I can complete the headspacing with their brass</span>
-a loaded cartridge will feel tighter in your completed chamber (finished rifle) than a virgin piece of brass will in the lathe. The loaded cartridge will have a wider neck dimension and will feel different in the chamber then the virgin piece of brass. swelling in the neck/shoulder junction will happen when a bullet is seated, this makes a difference
-even if you do not "feel" the virgin brass (unloaded)when closing the bolt, you should see a slight ring at the neck/shoulder junction of the brass. <span style="font-weight: bold">This is what Im looking for</span>. If you headspace this way, you should have light crush (feel) when you close the bolt on a completed barrel install with a loaded cartridge
-If you dont feel it, as long as you have this ring, you are supported

fireforming with .003-.004 crush on your virgin cases can be hard on the bolt lugs, especially with BATs, etc. Moral of the story is use the AI GO gauge to get very close to where you need to be, and headspace with the brass. As long as you're fireforming your own brass in your own chamber, AI chambers are custom built around the brass. If you want to buy formed brass from someone or 280AI Nosler brass for example, then chamber to a spec with your GO gauge.

Now please be aware that there has been a few different specs with the 280AI, specifically with dimensional variables in Nosler 280AI brass, but this is another discussuion...

 

[Just Jim]

Re: .223 Ackley chambers?

Thanks Bugholes-

I appreciate you sharing your experience!

By the way, the Krieger barrel and Stiller action are from you. GREAT customer service. It seemed as if I had barely set the phone down before that action arrived!

Thanks... Jim