cooper 280 ai

[bubba41]

guy's are cooper 280 ai sammi spec or original ? getting conflicting answers . even redding says the last 4 or5 fired cases sent to them are infact sammi spec. but cooper says old but you can use nosler brass . any help would be appreciated

 

[J E Custom]

guy's are cooper 280 ai sammi spec or original ? getting conflicting answers . even redding says the last 4 or5 fired cases sent to them are infact sammi spec. but cooper says old but you can use nosler brass . any help would be appreciated

Once a SAMME specification is excepted, All reamer manufactures and rifle manufactures have to comply.

They may alter the SAMME spec. but they have to identify the change on the cartridge designation
on the barrel.

So if it says 280 AI, it should be the SAMME Spec. chamber. But only a head space gauge will prove what it really is.

If you can borrow or buy a 280 Remington (Not the 280 AI gauge) you can check head space.

The SAMME AI is .014 to .018 shorter than the 280 Rem. (You can compare them on this site.
http://www.saami.org/PubResources/CC_Drawings/Rifle/280 Ackley Improved.pdf

And http://www.saami.org/PubResources/CC_Drawings/Rifle/280 Remington - 7mm Express.pdf

J E CUSTOM

 

[bubba41]

thanks je i'll find a gauge somewhere . if a 280 round will chamber that would make it original ? or is that a bad way to go about it?

 

[bubba41]

ttt

 

[yawn]

Cooper told me the same. Iv used my M52 since 2008 with nosler 280ai brass with no issues at all, over 12 firings. I can also comfortably chamber and fire form standard 280 rem ammo and brass again with no issues at all. I have traditional AI redding dies, not the latter supposed saami spec, which work perfectly.

 

[8andbait]

I emailed cooper about this issue because I bought cooper model 52 in 280 ai. This is my fourth cooper and I really like the rifles.

So, the person at cooper told me that they use the old 280 ai spec not the new one. I was concerned because I wanted to use nosler brass. They said I could use Nosler 280 AI brass or fire form regular 280 brass or shoot regular 280 ammo. So I have been using nosler 280 AI brass and I have not had any problems. The rifle is a laser beam with 168 berger classics .

Good Luck, you will be happy with your rifle.

Just send them an email with any questions and you will get answers quickly.

Gary

 

[8andbait]

I should also add that Cooper told me Nosler changed their brass slightly so it could be used in either chamber. I measure head space before and after and I only see about .002 difference between fired and new brass.

Gary

 

[bubba41]

what dies are everyone using ? i just bought the new sammi spec dies will i have to get a different shell holder?

 

[yawn]

I should also add that Cooper told me Nosler changed their brass slightly so it could be used in either chamber. I measure head space before and after and I only see about .002 difference between fired and new brass.

Gary

When was this ?
The first batch I picked up in 2008 and it has been just fine in the cooper. It also measures the same as the most recent lot I bought.

what dies are everyone using ? i just bought the new sammi spec dies will i have to get a different shell holder?

I'm using tradition AI dies with the nosler brass and a standard shell holder.
The supposed .014 difference in head space between the old and the new is less than 1/4 turn of the sizing die.

 

[bubba41]

redding dies made after 2011 are sammi spec ! looks like i need the shell holder

 

[yawn]

redding dies made after 2011 are sammi spec ! looks like i need the shell holder

I think youll be fine with a standard shell holder.
Assuming there is actually a difference and thinking about it logically if you have the Saami chamber and dies then a standard shell holder should be fine. If you have the traditional chamnber and saami dies then setting up the sizing die correctly should have it wound out to accommodate the .014 longer chamber and again a standard shell holder would be fine. The only combination that could be an issue would be traditional dies and a Saami chamber. A custom shell holder or milling a little off a standard shell holder or the bottom of the die would do. Iv had to do that for a couple of factory rifles in standard cals.

 

[J E Custom]

The dies can be set for ether chamber. the main thing to know is which chamber you have. Both chambers are good but with the headspace issue it is important to at least know what you have.

Then the choice of which ammo to use is yours. Ammo varies in size and can work sometimes
without a problem and other times will cause issues.

The 280 AI is one of my favorite cartridges and it is a shame that it has been screwed with and
that it made things difficult for a great cartridge.

If anyone choses to shoot both sizes of ammo that is there choice, but just because they can get
away with it does not mean they should.

Even the first firing can be a problem if the Head space is wrong and with a potential of .014
thousandths head space it can cause case head separation or thin the brass to a point that failure will soon follow.

I recommend shooting the correct ammo (Don't mix Nosler with other brands)depending on the chamber specs. and sizing to fit your chamber. then it will last and be safe for many uses.

When firing any round, the head space should never be more than .006 to .007 thousandths.

Just a word of caution

J E CUSTOM

 

[8andbait]

I bought everything this year, rifle, brass and redding dies. I only get about .002 difference in headspace between new nosler 280 AI brass and brass fired in the cooper.

I do have some factory 280 ammo I would like to shoot through it just to see what it does in case I am in a pinch while travelling and I need to buy ammo locally.

On a side note...if any of you guys are using 168 berger classic hunters do you mind posting your load data please. I have only tried H4831SC and have a good load at 59.6 gr but always looking for others.

Gary

 

[yawn]

The dies can be set for ether chamber. the main thing to know is which chamber you have. Both chambers are good but with the headspace issue it is important to at least know what you have.

Then the choice of which ammo to use is yours. Ammo varies in size and can work sometimes
without a problem and other times will cause issues.

The 280 AI is one of my favorite cartridges and it is a shame that it has been screwed with and
that it made things difficult for a great cartridge.

If anyone choses to shoot both sizes of ammo that is there choice, but just because they can get
away with it does not mean they should.

Even the first firing can be a problem if the Head space is wrong and with a potential of .014
thousandths head space it can cause case head separation or thin the brass to a point that failure will soon follow.

I recommend shooting the correct ammo (Don't mix Nosler with other brands)depending on the chamber specs. and sizing to fit your chamber. then it will last and be safe for many uses.

When firing any round, the head space should never be more than .006 to .007 thousandths.

Just a word of caution

J E CUSTOM

Hey Jerry,
I know what you are saying here and in normal circumstances I would say that is very good advice. But given the confusion that surrounds this topic I think its a good idea to think about it a little and apply some simple logic.
The OP, 8andbait and myself seem to have the same chamber. That is we can fire nosler saami 280ai brass with minimal stretching .002 and .000 in my case.
So with all things being as they should, that leaves us with two possibilities.

1, there is no difference between the old and the new and the guys that posted this are correct.
https://gunsmithtalk.wordpress.com/2012/07/17/280-ackley-improved-emperical-headspace-test/
If that is the case then any factory 280 rem ammo or brass or factory nosler 280ai brass or ammo will be fine as per PO Ackleys intentions.

Or 2, there is a .014 thou difference and we three have the shorter saami chamber. If that is the case then its supposedly .014 shorter than the original making the Nosler saami spec 280ai brass and ammo a good fit, but more to the point all standard 280 rem brass and ammo will be longer making it a tighter fit (.018 crush) and leaving no room for any possible case stretch.
The only possibility of case stretch would be using the supposedly shorter nosler 280ai product in a chamber that is longer than the saami and ignoring best fire forming practice.