280 AI brass Problem

[SeabeeKen]

Just rebarreled my Savage 110 to 280 AI with a Shilen select match barrel. Headspace is perfect checked 4 times. I picked up some Nosler custom brass and loaded some test loads. After firing I checked the cases and found a bit of a bulge just forward of the web of the case. Apparently these cases are smaller than they should be. Here are a few measurements:
New case rim = .469 Should be .473 according to my drawings
New case head = .467", fired case = .467", should be .470" according to drawings.
Body dimensions just forward of the web body junction are: new case = .466", fired case = .473"
Appears that the new cases are too small. Anybody else seen this?
Can someone give me measurements off of standard 280 rem brass. I dont have any here. Curious of the difference. Afraid to shoot this thing until i get it figured out.

 

[bheadboy]

My new 280AI, Rem brass was closser to .470 etc. and my fired cases .4715, chamber by R W Hart in hart bbl.

i think you may have two problems, small brass and large chamber.

Bob

 

[fayettefatts]

Could your chamber be a traditional (original) 280 AI rather than the SAAMI spec chamber?

 

[SeabeeKen]

I don't know Fayette. I have drawings on the SAAMI version but not Ackleys. I believe Bhead is be right. According to drawings, the 280 Rem head diameter is .470 before firing. My AI measures .466 before firing. SAAMI drawings show the AI head at .4685, almost .002 difference Small brass. SAAMI shows a chamber dimension at the head of .4710 and my fired AI brass measures .473, a difference of .002, an over size chamber. Waiting to hear from Shilen about this. Now, since the original Ackley version was made from 280 Rem brass fireformed, the head should be .470 so if I use 280 Rem brass, I should get back .004". This still leaves an over size chamber by .002". Is this within tolerance and safe to shoot? Bhead says his fireformed 280 Rem brass measures .471 after firing which is perfect.
Nosler sure fouled up the Ackley version because the drawing shows a .471 chamber and the brass at the head body junction as .4685, almost .002". Even the rim is smaller than the original 280, measuring .472 and should be .473.
I hope this issue is addressed before some gets hurt.
I'm attaching a pic of a fired and unfired Nosler case but it doesn't do the bulge justice. Hope it posts ok.
Even with a perfect chamber, there is still .005" difference between Noslers brass and chamber dimensions. Be cautious if anyone out there decides to use their brass.

 

[fayettefatts]

I see what you're saying. I don't know if that is considered excessive or not. Only thing I was getting at is that if it is not the SAAMI spec chamber then the dimensions could have greater tolerances since there are no set standards for wildcats. Could very well be just as bheadboy says.

 

[SeabeeKen]

Sure would be nice to have an original Ackley drawing. I'm heading out to see if I can find some 280 Rem brass for fireforming just to see if it will make a noticeable difference. With Nosler brass being that much undersized, it could be a dangerous situation. I'll keep you posted. Hope I can get brass, supplies are pretty tight around here these days.

 

[Rtheurer]

Ken

Send me an email and I send you my 280AI Reamer print.

at the bolt face Mine shows .4688 and at .200 ahead of the Bolt face ( where your bulge is) its .4675.

Looks like to me a classic example of the cartridge streching in the chamber from not fitting in the chamber tightly enough. Like when you set the shoulder back to far. In this case you may have to JAMB those bullets hard into the lands and fire form your fireformed brass..... Ha! Sure has that look in the pictures.
Can you feel a ridge or divit inside th ecase with a pick or paperclip?

RussT

 

[SeabeeKen]

No case stretch at all. It is where the case bulged bigger than the head. The diameter at that bulge point on an unfired case is .466 and on a fired case is .473. A .007" bulge. No groove inside the case like a head separation, just a bulge. The cases were Nosler 280 AI brass and did not need fireforming. They are smaller than fireformed 280 Rem brass. Not what Ackley designed. I'll never use them again. When I fireform new Remington brass, I will jam the bullet into the rifling just as I did my 243 AI. Apparently, Nosler change Ackleys specs and they make smaller cases.

 

[Rtheurer]

Looking at my print your brass is correct but your chamber is big. At the bulge the chamber should be .467 and after fireingthe brass is should srink back a lil giving you what you should have is .4665

How did you measure your headspace before and after firing the virgin brass? ( what type of tools did you use) Did the bolt close with a little resistance on the new virgin brass?

RT

 

[bheadboy]

Call Pacific Tool and they will email you a copy of the spec drawing of their reamer, you can compare vs a chamber cast.

Bob

 

[Rtheurer]

Dont even have to call. I have it right here from PTG. The reamer I own. Your welcome to have it via Email if you would like. Offer still stands.

RT

 

[tclaunch]

Just miked a fired 280AI case .200" above the bolt and is .4662" likely fired in a .467" chamber. This brass given me by a friend. I had a Henriksen reamer in 280 AI and sold it like a dummy, but will find the drawing around here and tell you what it states.

This discussion is a prime example why you should always purchase your own reamer!

 

[SeabeeKen]

Yeah, sounds like the chamber is oversize by about .007"
Shilen is gonna have to fix this. I headspaced with ptg gauges. I don't notice much resistance when closing on a round. Should i tighten up on the headspace gauge more? I think this barrel is going back. I owe Nosler an apology.
Just measured a 280 Rem case and it is smaller yet. Rim is .465 and head is .462.

 

[SeabeeKen]

TC, For what I paid for this barrel, I shouldn't have to buy a reamer, they should make certain it is right before it leaves their shop. .007" out of spec is ridiculous and dangerous. I could see buying a reamer if I was rechambering but not on a new barrel. Maybe i don't understand how this works, I dunno. I'm very disappointed in Shilen, I expected better than this. A select match barrel should not be this bad. Sorry folks, just venting. I greatly appreciate all the help.
I've learned there is a big difference is SAAMI drawings and reality also.

 

[Rtheurer]

Ken
Email with attached Reamer print sent via Email. : )

I think you got the double wammy on this one. Since your setting your own headspace via the Savage NUT and using headspace gages... I would take a piece of unfired brass and use that as the gage just to see what happens. I predict your troubles will go away. ( but maybe not????) If done this way whats the worst that can happen? Nothing really and you can always go back to using the go gage again... with no real Issues. If it was me I would pull the firing pin spring and ejector out to headspace off the brass to get a better feel for the resistance on the bolt....Making sure I had bolt greese on the lugs as to not gull them as well.

I might have to get some of that Nosler brass as it seems the perfect fit for my reamer. Been using Norma mostly when I can get it.

RussT

 

[SeabeeKen]

I think the brass is ok. The chamber is way too large. This barrel is gonna be going back. Let the gunsmith shoot it. It's so loose that there is no way the cartridge is inline with the bore. If I use a piece of brass to set headspace, I dont think it will change anything. The bulge will still be there because the chamber is still .007" bigger than the brass. Headspace is identical between a fired case and an unfired one. Thanks again.

 

[SeabeeKen]

Ok, Talked to Shilen and Nosler today. I saw the blueprint for the reamer used on my chamber. It is exactly right for the dimensions specified by SAAMI. Shilen said they will make it right to my complete satisfaction. The barreled action is on it's way to them as I write this. They are a GREAT company and I would definitely order from them in the future. I am waiting to find out why the brass measures .473 instead of .471 as the reamer print says. Shilen thinks the problem may be that to much was removed from the chamber when polishing the chamber. I agree with this. Removing .002" of stainless steel by polishing is some serious polishing I would think. Now, this is where it gets interesting. SAAMI drawing show the dimensions of the case (where the bulge is in my brass) to be .4685". They show the chamber dimensions at that point to be .471". A difference of 2.5 thousandths or 25 ten thousandths.
Now, on to Nosler. SAAMI case dimensions show .4685" and the actual measurement of the brass before firing is .466". A difference of 2.5 thousandths or 25 ten thousandths. Now we are up to a total of 5 thousandths. Nosler says that this is maximum but not excessive and that it is within production tolerances. So we add the .005" (which Nosler says is ok) to the .002" to that my chamber is over polished, and we have .007". Now, Nosler also says, the brass will shrink about .001" after firing so that means that the chamber should be .008" loose. .008" is way too much when I order a select match barrel and want accuracy. My cartridge is wandering around .008 in that chamber and is .008" out of alignment with the bore. I hope it all makes sense. It is an ongoing process and we will get it worked out. I'll keep you posted.

 

[bheadboy]

FYI i used R/P brass and Win brass 280 and fireformed on 2 280AI. they were larger than you measure form Nosler to begin with so this may reduce some of your looseness, on the new chamber/bbl when you get it back, for what it is worth , try a different brass mfg.

Bob

 

[Dave L Kiff]

The SAAMI 40 deg. gauge is not the same as Mr Ackleys -.004 gauge on the parent case angle of 17 deg. 15 min. There is from .005 to .014 difference from factory stack able tolerance but I only see .007 in most cases. The SAAMI reamer print that Nosler uses is a Ackley reamer print. it's that SAAMI would not pass a short gauge it had to be mathematically perfect.

 

[SeabeeKen]

It turns out the chamber was over polished at the rear. All dimensions are right except the area from the web forward about 3/8" where the case is bulging. Now I'm waiting to hear how it is going to be corrected. I'll keep you posted.