280AI Question

[30378]

I know in most instances you can fire regular ammo in an A.I. chamber. I noticed that Nosler 280A.I. brass has a spec length of 2.525". Normal 280 brass length is 2.540". Can I fire form 280 brass in a chamber that is cut for the Nosler 280 A.I. dimensions or should it be trimmed first?

 

[mac86951]

Well, I'm not an expert on this caliber, however, most AI rounds are fire-formed from standard ammo. IE you could use factory 280 ammo in a 280AI chamber to fire form. I would load to 280 specs (with correct powder charge for fire forming) and then trim after fire-forming. This will prevent the formed AI brass from being too short.

Please wait for others to chime in, but I think this is an appropriate method.

-Mac

 

[bheadboy]

the chambers all have some give in them for case streach upon reloading, then they are trimed back to "normal"

your chamber may or may not accept the longer brass without it getting into the throat. i would suggest you trim, assuming you know the chamber you have is the shorter of the two. if you are fire forming 280 brass it will shrink as the shoulder blows out and i would not trim it unless you have some difficulty closing the bolt on loaded ammo.

Bob

 

[p-man]

I would fireform it WITHOUT bullets - use cream of wheat or other non-projectile forming - 13 thousandths is alot of 'headspace' - if want to fireform with bullets, load conventional 280 brass - Ackley designed it so that conventional ammo had a very, tight and slight "crush fit' at the shoulder, and this resulted in the perfect case needing on neck-sizing for the Ackley chamber. Do your research on this but I would NOT shoot the Nosler-SAAMI 280 Improved in an original Ackley chamber.

 

[Rtheurer]

My Chamber in 280AI is 2.560. So there for 280 Brass works just fine when Fire Forming from normal brass.
This finish reamer is a PTG reamer. Print number 4771.

Im just guessing here but you would think that 280 Brass would and should fit the 280AI chamber so that it can be fireformed... That is the whole point of the cartridge anyway.

30378: is that the chamber length of 3.525 or the trim too length listed some where?

RT

 

[Clod-NC]

Hi 30378,hi all
I went through the thread and although I understand you can be worried over such an issue,I don't understand why you're worried over a Nosler dimensionned AI chamber....Does such a thing exist? I know AI chambers in various calibers exist and work quite good,but I ignored they were cut to a special brass maker's specifications....Go and check SAAMI specs,it will probably help you solve your problem,I really don't think you should consider trimming a case that, if already AI speced measures 2.525",and if normal .280" measures 2.540" fired in a chamber that should be 2.575 or 2.565 in over all length,I'm not too sure of the exact SAAMI figures,but it's either of the 2.If you fireform from normal 280 cases,consider the fact that the case taper will be less,the general body longer,the neck probably shorter(check SAAMI specs to make sure),so your original case in 280 might as well need a little more brass to cope with the improvement,and so don't rush upon trimming...Just my 2 cent,hope it helps.

 

[expiper]

HI 30378,,listen to Claude,,,there are a myriad of chamber dia/length/etc associated with anything AI,,!!!--for your own info you should measure the actual chamber length and the length /of the ctgs that you are going to use,,,that way ther is NO guessin !!!,,if you are using shotgun powder and NO bullet the length is not as important...but,if you are using a bullet and you jam the case mouth against the front end of the chamber the pressure will skyrocket!!! very dangerous,,,varous gunsmiths have various reamers--check yours out!!,,,Roger

 

[p-man]

All you guys need to read up on the history - compare the cartridge diagrams of the 280 Rem (actually 7mm Express) and the 40 degree original PO Ackley Improved and the Nosler version - the shoulder of the reg 280 was supposed to be a tight fit against the chamber of the Ackley. It was in his writings. This ensured that there was NOT a headspace or bolt thrust issue when fire forming AND it simplified the loading in that there was very little else to do with the brass other than just load it - very little trimming if any, usually none, neck size it and go. As to the pressure one of you is concerned with the standard 280 is actually expanding into a chamber about 5 percent larger, so there will be less pressure than firing in a standard chamber - and you are not "jamming the case mouth against the front end of the chamber" - where the contact is made is shoulder or round to shoulder of chamber. There is NO question about it - the Nosler-SAAMI version and the original Ackley are 13 thousandths different.

 

[Rtheurer]

Thanks P man

This example right here is why I purchase my own reamers from PTG or who ever. Before I order I confirm that the chamber is going to be a close match to the existing FL dies off the shelf there for eliminating the need for any custom ( read more expense).

As Expiper and P man said, knowing your chamber dimensions is important. This can be very fustrating as you can see.

RT