280 to 280 AI

[UBER7MM]

Nothin', but as we all know, what's that got to do with anything? Sometimes we just got to fix what ain't broke... Actually, I will probably leave it the way it is. I am enjoying the discussion.

I hear ya'. I think the 280 Remington, as is perfectly fine on its own. And I'm learning about the AI as well. Down side is higher pressure. Setting back the barrel would be a show stopper for me. If it were just a bit of play with the finish reamer then it might be a consideration. Lot of folks like 'em. Lots of comparison with the 7mm Rem Mag.

Enjoy,

[Newtire]

I could of set back a couple rifle barrels in half the time some of you have spent here typing arguments on why we don't need to do all that work. While we're at it and setting head space anyway. We could square up the Remington receiver face.

My question was about how to do this to a single-shot H & R but not too practical setting that one back. I kind of get the idea that I could just do the same thing I did to make the .280 cases out of those .30-06 cases but the wildcat I would create would be a little longer than the normal 280 AI. Since it's not too bad a rifle as it is, think I'll just leave it alone.

[swheeler]

Friendly Google:
http://gunsmithtalk.wordpress.com/20...eadspace-test/

Interesting yes, but has absolutely NOTHING to do with the discussion at hand. This internet expert is comparing TRADITIONAL 280AI to SAAMI 280AI, nothing at all about reaming an existing 280REM chamber to AI configuration, be it the traditional or the saami spec. If you take him at his word/pictures(I think I'll believe SAAMI and the reamer manufactures over him) then BOTH AI configurations will have to have barrel set back to remove the .017" too deep on original 280 chamber. Since it is now a legitimate/standardized cartridge I see no reason to pick the traditional reamer out of the line up, use the SAAMI reamer and gages, set back a thread and have fun

[B R Shooter]

You are one hard headed person, and I mean HARD!

[swheeler]

Not hard headed, just trying to disspell internet myths and wives tales

[B R Shooter]

The only myth and incorrect information being given here is your .017" that is floating around in your head.

[nanuk]

Hi, I had the thought of trying out the .280 Improved. My trouble is that I have a .280 Handi-Rifle with a nice 26" barrel. I see I can get a 7mm-08 barrel for this thing but then those are only 22" long. So, the gain I got from the "Ackley-ization" would just be lost by the shorter tube. I can't set this barrel back as it's a single shot.
Any thoughts?

Tim, on the GBO site did his by going to the shoulder/neck junction as per BR Shooter, and stamped it 280AckImpImp

as to the discussion/argument going on here:

When I did my research on the AI line, I got ahold of the Ackley books and read on why he did as he did

my understanding is that the Ackley shoulder actually rotates around the "Datum Line", and has nothing to do with the neck/shoulder juction. That is WHY there is a "CRUSH" and not just a good fit. with minimum spec ammo, in a chamber reamed as per BRShooter's suggestion, you could have a Headspace issue

so, SWheeler is discussing the Ackley theory, and BRShooter is discussing using an Ackley reamer to make a Wildcat, that one "Could" fire factory rounds in.... IF reamed correctly.

this is MY understanding.. .YMMV

[Newtire]

Sorry, but you lost me a couple of datum lines and shoulder angle differences back!

[swheeler]

I downloaded the SAAMI drawings to post here, max cartridge-min chamber, think you can click on the link and open, hope you can anyway

[swheeler]

Left click on the print and it will enlarge to read.

breechface to shoulder/neck junction 280 rem-2.1924 remember this chamber is already there -existing
breechface to shoulder/neck junction 280 Ack- 2.1742
--------
.0182"


If you started with a min spec 280 rem chamber(which you aren't going to find in a production rifle;0)and reamed to max spec 280AI you still are going to be over by some margin. Best do it right from the start and keep all your fingers and both eyes, then we won't have to use handles like righteye and lefteye

If anyone has Nosler #6 reloading manual it has both Sammi max cartridge drawings for 280 and 280AI, they show 280 rem is .017" longer to neck/shoulder junction

4d reamers drawings shows 280 rem neck/shoulder .024" longer than TRADITIONAL 280AI reamer

[B R Shooter]

Wheel ol' boy.....you are back-assward. Look at your OWN drawings again. A standard 280 is 2.1924", the AI is 2.1742". If you set a barrel back and reamed to this dimension, the chamber would be SHORT by .018", and I doubt you would ever close a bolt on the brass this way. Maybe you would, but one thing is for sure, you surely wouldn't have a danger of case head separation, everything would be extremely tight.

Here are the chamber prints from JGS:



JGS shows a .004" short dimension to the N/S line, which is standard with any of the reamer makers. Call ANY reamer maker, and ask them what the AI GO gauge is, and you will be told, it is a .004" short gauge that has the same shoulder angle as the parent cartridge. This .004" is for the brass crush when closing on a standard piece of brass. Ask them about the .018" shorter dimension.

When I started this "discussion", I commented about reaming to the EXISTING N/S and no more. The only thing this would do is give at most, .004" excess headspace. And this could easily be handled by long seating a bullet.

This .017", that has now morphed into .018", was taken out of context, was touted as a LONGER chamber, which it isn't. In effect, you could not ream an existing chamber and use a ACK GO gauge, because it would not have the N/S to gauge to. If you set the barrel back, then you could ream to the shorter gauge.

I have no idea why there are so many variable dimensions around on this cartridge, to me, people could create a bad situation if they aren't thinking things through.

One more thing, a factory chamber is BIG, I don't think you would be able to buy a reamer as big as that, most reamer makers grind to a minimum SAAMI. Trying to ream a factory chamber and think your reamer will match the factory chamber won't happen.

I'm finished with this discussion. There is a saying that is "you can't argue with a liberal". It's true. I have no idea of your political orientation, but you are so fixed on wrong information, nothing gets through.

[swheeler]

You HAVE to set back to ream the Ackley chamber so the headspace will not be excessive-period. The go-gage of the parent cartridge becomes the no-go gage, A CORRECT 280AI CHAMBER WILL NOT CLOSE ON A 280REMINGTON GO GAGE-PERIOD. With the way you describe in your own words- ream just to the neck shoulder junction- you are never going to get a slight crush fit.


Liberal? Your the one with Liberal headspace!

[felix]

Ackley's chamber design rule has always been a crush fit on a new SAAMI sized case during bolt closure. That was his chamber rule which makes his case slopes secondary in design. My dad was present when PO and Roy Weatherby were discussing chambers at one time. ... felix

[B R Shooter]

You HAVE to set back to ream the Ackley chamber so the headspace will not be excessive-period. The go-gage of the parent cartridge becomes the no-go gage, A CORRECT 280AI CHAMBER WILL NOT CLOSE ON A 280REMINGTON GO GAGE-PERIOD. With the way you describe in your own words- ream just to the neck shoulder junction- you are never going to get a slight crush fit.


Liberal? Your the one with Liberal headspace!

That's what I said! An Ackley go gauge is .004", READ FOUR THOUSANDS, shorter than the parent go-gauge. Where is your coveted .017", or .018" in all this?

I said it is possible to ream to the existing N/S and fireform. It is only .004" long. Where is your plus .017"?

[swheeler]

Ackley's chamber design rule has always been a crush fit on a new SAAMI sized case during bolt closure. That was his chamber rule which makes his case slopes secondary in design. My dad was present when PO and Roy Weatherby were discussing chambers at one time. ... felix

Thank you Felix! Now I just have walk away this is becoming a waste of time, think I go ream an Ackley chamber correctly

[leftiye]

No ship! Frum the git go.

[swheeler]

To make it work like Ackley intended the barrel needs to be set back

Do tit this way Crabo and you'll be fine

[Changeling]

You will never be sorry if you do, just make sure you have a top notch gunsmith do the work. I have one set up on a custom 1909 Mauser action with a HART Magnum barrel that is absolutely the finest shooting rifle I have ever shot! The speed and accuracy is amazing.
Good luck with your project. Forget about a 7 mm Mag. the barrel will loose 2 to 300 fps after 1000 to 1500 rounds. The 280 AI will be going strong and kick the Mag any day of the week.

Do it properly and set the barrel back....or better yet buy a new barrel blank. Hard telling where it might end up might as well make it work with ammo you can buy at the store.

280 AI is high on my list. I love my 280. When I do build a 280 AI I will probably set it up as a heavy long range rifle.

[nanuk]

My question was about how to do this to a single-shot H & R ...

Newtire... start with a 7mm08 and ream away!