Calling all AI shooters

[Scoobyh]

So, my wife asked my brother what I wanted for my birthday being I haven't given her any ideas. Well, he told her a barrel for a build I have been dreaming about and she ordered it!

270AI 1-8 finished at 30" from Pac-nor Savage pre-fit.

I have never fire formed rounds so this will be new to me. I need some of y'all's knowledge.

#1
Does the bullet need to be kissing/jammed into the lands for forming?(seen conflicting info)

#2
What charge weight to use for forming? A 270 WIN mid weight charge for the powder, bullet combo?

#3
Do I need to anneal before loading and fire forming? Heard it can help with split shoulders.

#4
Load data
If I understand correctly a 270 AI has about 5-7% more capacity than the 270 Win and would likely have powder charges around that much heavier than the 270WIN.So I could work up loads up to 7% over book loads for the 270 and be in the ballpark(start that much lower also and work up).
Is this correct?

I'm sure I will have more questions.

Thanks in advance.
Scott

 

[MudRunner2005]

This should help.

https://www.longrangehunting.com/threads/25-06-ai-brass.159341/#post-1118370

If you have any other questions about, feel free to ask.

 

[Scoobyh]

Thanks Mudrunner.
That does answer some questions, but brings up more.

JE Customs states
Quote
The best thing to do is get a 25/06 AI reamer and a 25/06 head space gauge and that way you can use standard 25/06 ammo or brass and fire form to the AI cartridge without any issues.

Normally if the chamber is set up correctly it will be very accurate while fire forming so you don't have to do anything special during fire forming (Most hunt with the factory loaded brass and fire form at the same time.

J E CUSTOM
End

So I could use a standard 270 WIN headspace gauges?

Could I then full length size with a standard 270 Win die just until they fit in my chamber and seat bullets into the lands like you said?

 

[dok7mm]

#1 You can use jam, or you can run a .284 mandrel into the necks of your .270 necks. Then you can use a .270 bushing die to progressively size down the neck until your bolt will close, with some pressure, in your rifle's chamber. This will give you a false shoulder on the rear 1/4 or so of your .270 neck and will hold the case firmly in your chamber for fire forming to A.I.

Just start by using the bushing to reduce 1/2 of neck, or so, and try chambering. Keep adjusting bushing down in increments, until case will chamber, with some bolt pressure. Tighten die and run all your brass, and you're ready to load and form. Annealing always helps.

 

[Varmint Hunter]

IME it is easier to just jam long bullets and start with an appropriately reduced load. A little trial and error should get you nicely formed cases.

 

[DocDoc]

IME it is easier to just jam long bullets and start with an appropriately reduced load. A little trial and error should get you nicely formed cases.

What JE was alluding to with the Ackley case is that the go-gauge is 0.003 shorter than the parent, in this case .25-06. So a standard .25-06 case should be a crush fit in the Ackley chamber, and not require jamming bullets.

I just set up my new.260 AI. I set the barrel with the AI go gauge. The bolt would not close on the parent .260 go gauge. The bolt closes with some pressure on the .260 cases I have, so when loaded they will be held firmly against the bolt face and form well and safely. You should always check that the unloaded parent case needs pressure to close, so you do not have excess headspace from a short case on the fire forming.

 

[MudRunner2005]

Thanks Mudrunner.
That does answer some questions, but brings up more.

JE Customs states
Quote
The best thing to do is get a 25/06 AI reamer and a 25/06 head space gauge and that way you can use standard 25/06 ammo or brass and fire form to the AI cartridge without any issues.

Normally if the chamber is set up correctly it will be very accurate while fire forming so you don't have to do anything special during fire forming (Most hunt with the factory loaded brass and fire form at the same time.

J E CUSTOM
End

So I could use a standard 270 WIN headspace gauges?

Could I then full length size with a standard 270 Win die just until they fit in my chamber and seat bullets into the lands like you said?

You should be able to use a set of regular .270 Winchester Go/No-Go gauges for it, as long as the chamber was not cut too deep.

I don't use factory ammo for mine for 2 reasons. 1) Factory ammo is loaded hot, and you have a greater chance of cracking brass while it's forming during it's first firing, and then you just wasted a shot. And 2) When you fire-form brass to an AI chamber, the neck shrinks .020"... So, I use .270 Win brass for my .25-06 AI, because after I neck it down, I can trim it .020" too long, and then when I shoot it, the brass forms at the proper length. And because AI brass tends not to grow like standard cartridges with lower shoulder angles, you shouldn't need to trim the cases again, which is why I like to knock-out that process from the get-go. It also keeps you from having carbon-ring buildup in your chamber because of short brass.

As for FL sizing, no, you can't, because the shoulder and wall taper have grown, and they won't fit in standard dies. You will need to buy a set of .270 AI dies.

Also, for an AI cartridge, I recommend neck-sizing your brass once you get the cases formed to your chamber, to increase accuracy.

 

[Scoobyh]

#1 You can use jam, or you can run a .284 mandrel into the necks of your .270 necks. Then you can use a .270 bushing die to progressively size down the neck until your bolt will close, with some pressure, in your rifle's chamber. This will give you a false shoulder on the rear 1/4 or so of your .270 neck and will hold the case firmly in your chamber for fire forming to A.I.

Just start by using the bushing to reduce 1/2 of neck, or so, and try chambering. Keep adjusting bushing down in increments, until case will chamber, with some bolt pressure. Tighten die and run all your brass, and you're ready to load and form. Annealing always helps.

Ah, that understand what you are saying. I personally like that more than jamming.

What JE was alluding to with the Ackley case is that the go-gauge is 0.003 shorter than the parent, in this case .25-06. So a standard .25-06 case should be a crush fit in the Ackley chamber, and not require jamming bullets.

I just set up my new.260 AI. I set the barrel with the AI go gauge. The bolt would not close on the parent .260 go gauge. The bolt closes with some pressure on the .260 cases I have, so when loaded they will be held firmly against the bolt face and form well and safely. You should always check that the unloaded parent case needs pressure to close, so you do not have excess headspace from a short case on the fire forming.

Ok, I understand about the excessive headspace. I'm building on a Savage with a nut set up so I have just a wee bit of adjustment.

You should be able to use a set of regular .270 Winchester Go/No-Go gauges for it, as long as the chamber was not cut too deep.

I don't use factory ammo for mine for 2 reasons. 1) Factory ammo is loaded hot, and you have a greater chance of cracking brass while it's forming during it's first firing, and then you just wasted a shot. And 2) When you fire-form brass to an AI chamber, the neck shrinks .020"... So, I use .270 Win brass for my .25-06 AI, because after I neck it down, I can trim it .020" too long, and then when I shoot it, the brass forms at the proper length. And because AI brass tends not to grow like standard cartridges with lower shoulder angles, you shouldn't need to trim the cases again, which is why I like to knock-out that process from the get-go. It also keeps you from having carbon-ring buildup in your chamber because of short brass.

As for FL sizing, no, you can't, because the shoulder and wall taper have grown, and they won't fit in standard dies. You will need to buy a set of .270 AI dies.

Also, for an AI cartridge, I recommend neck-sizing your brass once you get the cases formed to your chamber, to increase accuracy.

I'm not planning on shooting factory stuff to form from so that shouldn't be a issue. I was talking about the initial FL sizing before I fire form. I know that after they are formed I will need a AI FL die.




Now I am slightly confused if I should use a standard 270 WIN or AI go gauge.
Could I set the headspace with a 270 Win go gauge, then use a 270 Win FL die and just bump the shoulders until the bolt closes with slight resistance on the empty case?

Can I use a standard 270 Win neck sizer after I have formed brass?

Does anyone know the trim length on 270AI?

Thanks everyone for all the info so far, and sorry for all the questions.

 

[MudRunner2005]

If you can get your hands on a set of AI gauges, go that direction.

Standard trim length on most TRUE "Ackley Improved" cartridges, should be the same as the SAAMI case length for the parent cartridge. Example, .25-06 AI uses the same 2.494" as a standard .25-06. When you trim for an AI cartridge, prior to fire-forming your brass, you will want to trim them 0.020" too long. That way when the case forms in the chamber, it should come out exactly the right length, or within a 0.005 tolerance.

 

[Scoobyh]

If you can get your hands on a set of AI gauges, go that direction.

Standard trim length on most TRUE "Ackley Improved" cartridges, should be the same as the SAAMI case length for the parent cartridge. Example, .25-06 AI uses the same 2.494" as a standard .25-06. When you trim for an AI cartridge, prior to fire-forming your brass, you will want to trim them 0.020" too long. That way when the case forms in the chamber, it should come out exactly the right length, or within a 0.005 tolerance.

Thanks MudRunner.

I can special order AI headspace gauges through Midway. It's a little wait but it will be a little while before I get the barrel. I would rather do it the right way the first time.

 

[orch]

Ah, that understand what you are saying. I personally like that more than jamming.



Ok, I understand about the excessive headspace. I'm building on a Savage with a nut set up so I have just a wee bit of adjustment.



I'm not planning on shooting factory stuff to form from so that shouldn't be a issue. I was talking about the initial FL sizing before I fire form. I know that after they are formed I will need a AI FL die.




Now I am slightly confused if I should use a standard 270 WIN or AI go gauge.
If you are going to buy a go gauge for the build may as well get the ai... if you are borrowing one and they only have the 270win gauge then that'll work too... I have rebarelled my savages numerous times and have used a fired case with/without a piece of electrical tape on the case head (poor man's no-go/go gauge) .... AI chambers are designed to headspace with the parent case...

Could I set the headspace with a 270 Win go gauge, then use a 270 Win FL die and just bump the shoulders until the bolt closes with slight resistance on the empty case?
Might work if the brass you are starting with isn't at the low end spec for headspace... if you are starting with virgin factory brass your 270 win FL die may not even touch the shoulder until you are really squeezing it down.... beauty of having the savage barrel nut system, you can set the headspace where ever you want so you could set it at the low end of the headspace and have a tight chamber but could run into issues if you need to fire some factory loads that aren't at the low end of headspace...

Can I use a standard 270 Win neck sizer after I have formed brass?
Probably not if it is a caliber specific neck die all the ones I have are reamed very close to chamber specs and your AI brass would get squeezed back down to almost standard 270 win dimensions.. if it's something like a universal lee collet die (I've never used one so I'm speculating) it may work...

Does anyone know the trim length on 270AI?
Should be the same as standard 270win as the chamber is designed to fire factory loads, but you will probably never have to worry about trimming to length to avoid your cases getting too long for the chamber, when they fire form they will shorten quite a bit... probably around 0.020" or so... and afterwards AI cases tend not to "grow" very much on subsequent firing/sizing cycles... after the initial fire forming I usually measure all my brass and trim them down to the lower oal range of the fired brass to even them all up for consistency's sake (you might find one or two that really shrink compared to the rest wouldn't want to trim that short)
Thanks everyone for all the info so far, and sorry for all the questi

Orch

 

[DocDoc]

The standard .270 go gauge becomes the no go gauge for the .270 AI. The .270 AI go gauge is several thousands shorter to ensure that the standard .270 case is firmly held against the bolt for safe fire. There should be a "crush" fit on the standard case before firing. I.e. It takes a little extra force to close the bolt on the unformed case.

 

[Scoobyh]

Thanks orch and Doc for the info.
I am going to get the AI gauges. I feel a lot more confident about my first semi wildcat.

 

[waspocrew]

The AIs are a lot of fun. I just set up my Savage 22-250 AI recently and it was a great learning experience. I don't really have much to add to what's been said before - I picked up AI gauges from PT&G and had them in a week. Once I set the headspace, I chambered unfired brass and could feel resistance on the bolt when chambering and knew I was set. I formed brass with factory loads and didn't have any issues with split shoulders.

You're going to enjoy the rifle! Have fun with the project!