280AI question

[CjC73]

So I have a remage 280AI barrel I installed using a 280AI go gage and a 280 Rem go gage as the no-go gage.

I screwed the barrel on till it hit the go gage and tightened the nut. I then put the 'no-go' gage in and it still closes, but with some slight resistance and the bolt wouldn't pull the gage out either.

Is this normal? Is this what allows me to shoot 280 Rem brass to fireform?

Just want to make sure I did this right.

 

[shortgrass]

If the bolt has a spring loaded plunger type ejector, remove it before headspacing. The bolt should not close on the .280 Remington "GO" gauge, as it has become the "NO-GO". Hook the rim of the gauge under the extractor before inserting into the chamber.

 

[antelopedundee]

If you are going to be doing this a lot there is a tool/jig one can buy to make removing the ejector easier. It costs around $35 from Brownells.

 

[CjC73]

If the bolt has a spring loaded plunger type ejector, remove it before headspacing. The bolt should not close on the .280 Remington "GO" gauge, as it has become the "NO-GO". Hook the rim of the gauge under the extractor before inserting into the chamber.

ok, I'll try and get the ejector pin out tonight. Will that keep it from headspacing correctly?

So if the bolt won't close on the 280 Rem go-gage, I won't be able to fireform 280 Rem brass? Or it'll need to go thru the AI FL die first.

 

[antelopedundee]

ok, I'll try and get the ejector pin out tonight. Will that keep it from headspacing correctly?

So if the bolt won't close on the 280 Rem go-gage, I won't be able to fireform 280 Rem brass? Or it'll need to go thru the AI FL die first.

What you should care about is if the bolt closes on the .280 Rem brass that you will be fire forming with. Most smiths chambering for an AI cartridge use the parent case as the no go gauge. I think I got that right. Why would you not use .280AI cases unless you want a specific brand that's not offered in AI? If I was in your shoes I'd just set it so that the bolt will just close on a .280 cases with a tad of resistance. In order to account for any differences in case dimension, I would also seat the bullet so that it's lightly jammed into the rifling. You want the case snug in the chamber and all of the pressure to blow the shoulder forward and not stretch the case in the web area. Git R Formed on the first try. You want to make sure that your .280AI cases don't end up either too short or too long. If too short you will have to FF them again. If too long you will need to set the shoulder back.

 

[shortgrass]

ok, I'll try and get the ejector pin out tonight. Will that keep it from headspacing correctly?

So if the bolt won't close on the 280 Rem go-gage, I won't be able to fireform 280 Rem brass? Or it'll need to go thru the AI FL die first.

A good part of your problem is you are mixing gauges. If you are gonna' use a .280AI "GO" gauge you should be using a .280AI "NO-Go" gauge, not the "go" gauge for the .280 Remington as the "No-Go".. You shouldn't only remove the plunger style ejector and spring, you should be removing the firing pin assembly, too. Gauging headspace requires a light touch, and that can't happen with the bolt not stripped. The only part you can leave in is the extractor, and the gauge should be hooked under the extractor before inserting it into the chamber. In my personal .280 AI (SAAMI/Nosler) I get no crush fit on .280 Rem., so I firmly jam the bullet to fire form,,,,,,, and my .280AI gauges at "GO" plus .001" using a SAAMI/Nosler "Go" gauge (with steel shim to measure how far from "Go" I am). The barrel you bought is most likely the SAAMI/Nosler, but I would check with the seller to be certain. The idea behind fire forming Ackley Improved cartridges is to 'trap' the parent case between the bolt face and the neck/shoulder junction in the barrel with 'crush fit'. Doing it that way insures that the case stretch at the front to fill the chamber, instead of just in front of the head, which is NOT where you'd want the brass thin. If the "crush fit" of the case can not be accomplished, even though the chamber gauges correctly, a solid jam of the bullet usually works well. I use a "middle of the road" load to fire form with, and that fully forms the Ackley case.

 

[David Emerson]

When I chamber an AI I use the parent go gauge and set a .005 crush.

 

[CjC73]

I rented gages from 4D and that's what they sent. AI go and a 280 go, saying that is the AI no-go. It's a saami 280AI.

I had a borrowed set of AI gages originally (go and no-go for the AI) but I had to remove the barrel and needed to set it again . I was told by numerous people that removing the ejector wasn't necessary and didn't the first time.

If I was in your shoes I'd just set it so that the bolt will just close on a .280 cases with a tad of resistance.

That's the way it is now.

 

[CjC73]

When I chamber an AI I use the parent go gauge and set a .005 crush.

How do you set the amount ?

 

[shortgrass]

When I chamber an AI I use the parent go gauge and set a .005 crush.

That makes the "traditional" Ackley Improved.

 

[David Emerson]

That makes the "traditional" Ackley Improved.

Works for me. Of course set the bullet in the rifling and use a hard charge of say H4895 to fire form. If when you fire form you can feel the primer proud you do not have enough pressure. Why the .005 crush. And is there anything wrong with the traditional ackley improved? Seems it started with PO in the 50,s. The main is don,t stretch the web in fire forming. I also use unique with a light bullet to fireform. All said and done don,t stretch the web. To add. When fire forming use a high pressure load so the neck grips the chamber and does,nt shorten as the shoulder blows out.

 

[David Emerson]

How do you set the amount ?

Screw the action on the barrel and when you can put a .005 feeler gauge between the barrel and action your chamber is where it needs to be with a go gauge.

 

[nkyshooter]

So I have a remage 280AI barrel I installed using a 280AI go gage and a 280 Rem go gage as the no-go gage.

I screwed the barrel on till it hit the go gage and tightened the nut. I then put the 'no-go' gage in and it still closes, but with some slight resistance and the bolt wouldn't pull the gage out either.

Is this normal? Is this what allows me to shoot 280 Rem brass to fireform?

Just want to make sure I did this right.

I didn't read every post in the thread so apologies if I am rehashing ...

By definition an "AI" chamber can safely shoot the original/parent case. This means you should be able to safely chamber and fire a 280 Rem in a 280 Rem AI chamber ... and they are almost always amazingly accurate even with shooting the non AI parent in the AI rifle. Therefore - a 280 Rem Go guage will not suffice as a no-go guage for either a 280 Rem or 280 Rem AI.

I have a 260 AI ... I used the 308 go and no go guages for headspacing - it works perfect. I'd check with a smith to be sure but you should be able to use 280 Rem/270win/30-06/25-06/etc go and no go guages to headspace your 280 AI. If not then I suggest to be safest, get your hands on 280 Rem AI go/no go guages.

BTW - I have many times for my own personal use/rifles, used a go guage as a no go guage by adding 5-6 thou of additional length ... electrical tape can work very well for this for a very limited # of bolt closes (2-4). Take this for what it is worth and at your own risk - be cautious ...

 

[antelopedundee]

I rented gages from 4D and that's what they sent. AI go and a 280 go, saying that is the AI no-go. It's a saami 280AI.

I had a borrowed set of AI gages originally (go and no-go for the AI) but I had to remove the barrel and needed to set it again . I was told by numerous people that removing the ejector wasn't necessary and didn't the first time.



That's the way it is now.

Perfect.