280AI Nosler brass alert

http://gunsmithtalk.wordpress.com/2010/ ... ved-alert/

280 Ackley Improved Alert

A few years back Nosler decided to bring the 280 Ackley Improved into their list of custom brass and rifles. In order to do this they wanted to take the 280 AI to SAAMI and have it standardized.
Part of the process of standardizing the cartridge was for Nosler to see if other manufacturers had worked with it. They found that Remington had been chambering the 280 in their custom shop. Now here is where the alert comes in. Remington’s Custom Shop chose to shorten the headspace on the venerable design by .014″. When Nosler sent drawings to SAAMI they picked up that number as well.
So by a vote of the members of SAAMI the commercial established specifications for the 280 Ackley were changed from the original design. The reason reported for this change is that Remington believed it was necessary in order for factory 280 Remington ammunition to be fireformed safely in an Ackley chamber. Apparently they did not know that Ackley was the single most successful wildcatter of the 20th century. While he was not the first guy to create and “improved” design, he was the first to standardize the idea and create a safe method of fireforming factory ammo in improved chambers.
Ackley’s method was simple, he simply used a headspace gauge .004″ shorter than the factory case. This shorter headspace assured that the cartridge would be held tight between the bolt face and the junction of the neck and shoulder of the chamber during fire forming. Ackley’s method worked fine for more than 50 years before these alterations to his design were made.
Bottom line for anyone who now works with the 280 Ackley Improved you must decide which version of the chamber you will use; the SAAMI or the Ackley; you cannot safely use the Nosler brass in a traditional Ackley chamber, although it would still be safe to fire form factory ammo in a SAAMI/Nosler chamber.




can lead to flattened primers if you have a standard 280AI chamber that they have been chambering for 40 years





Why would they do that? :x

Guess I won't be buying any Nosler 280AI brass anymore!

And I guess the real question would be; Why doesn't Nosler put a warning on or in the box?

Wood, please enlighten me.

From looking at the side by side drawing, the difference between the Nosler/SAAMI spec. dimension, which is a bit shorter, when compared with original Ackley/standard dimension, is only .0143" at the neck juncture, and only .0142" at the shoulder. What you're saying is, the flattening of the primer was due to slight headspace that was created when the shorter Nosler brass was use. I can see what you're saying but, do you think this was the case here! I punched out a lot of primers that look like that in the picture, usually match primer, from a few of my rifles. I attribute that more to exceeding max load than anything else. When I first developed load for my 338 Lapua Ackley, I have the impression that since, I have an Ackley chamber, I can just exceed the max load listed for a regular 338 Lapua cartridge and be alright. Luckily, I didn't follow that route because it turned out the rifle maxed out much below what is max on several reloading manual for the regular Lapua. What I failed to realized at that time was that, my rifle has 9.35 twist barrel, and most of the load listed for the 338 Lapua was developed from a 10 or 12 twist barrel.
So in actuality my improved chamber did not gain much in velocity when compared with the regular chambering. As a matter of fact I'm a bit slower. The only advantage I have against the regular Lapua besides the cool factor was an extended brass life and the ability to shoot VLD's.

So, what I'm saying here is, it all boils down to individual rifle, and how you develop your loads. Having an Acklyrized chamber which theoretically equates to increase case capacity doesn't necessarily mean you can always exceed the load listed for the regular cartridge and consider it safe.

Hey DF

The load that was shot in those cases was the same load I have been shooting for a couple of years and not at max. Normal headspace for an unbelted case is in the range of 0 to .008". With the Nosler 280AI cases the headspace as measured from a new case to once fired was .017". This in a barrel chambered and installed by Hart on a Sako action.

What happens with too much headspace is that the firing pin slams the case forward that .017", the primer fires and the jetting action of the primer charge against the inside of the primer cavity slams the primer backward to the bolt face and then the case charge fires and expands the case so the case head slams back to the bolt face. Since the primer is out of the case head that .017" it gets flattened from the forces when trying to reseat in the primer pocket.

The purpose of the Ackley conversion was to take the parent cartridge, chamber it with a negative headspace of -.004" and hold the case tight between the case head and the contact at the neck/shoulder junction. The chambers were typically reamed by gauging with a 280 rem reamer with -.004" short of a go-gauge. That keeps the primer from backing out and holds the case while it expands to the chamber walls. With the shorter distance in the 280AI brass to the 2 points that define headspace in this instance (case head and neck/shoulder junction), the case doesn't expand in the normal fashion of fire forming 280 remington brass to 280 Ackley dimensions.

Before finding this out I assumed that since it was marketed as 280 Ackley brass it would be similar to any other beltless caliber like a 30-06 and have headspace somewhere in the range of .002" to .010". That is the range of readings I get on all of the beltless caliber guns I reload for (11 different calibers 27 different guns). Previously I had fire formed 280 remington caliber cases with this same load and had no problems.

In this case there were no pressure signs (brass flow on case head, excess velocity, hard bolt lift) and the cases have been reloaded and are holding primers fine.

I assure you if someone put out 30-06 brass with a headspace of .017" (case head to datum line) we would never hear the end of it. To market it without a warning is irresponsible at best and dangerous at worst. To change a dimension that has been in practice for 50 years because Remington is doing something their own particular way and then put an official stamp on it is unforgiveable to me. What's next? They decide to change the 30-06 dimensions?

I have read that this change happened in conjunction with the dimensions for the 280 remington dimensions changing but I have not verified that and all the drawings I am finding are the ones I have had for years. The reason shown in the article of Remington feeling it was necessary in order to safely fire 280 remington loads in a 280 Ackley chamber doesn't hold water IMO.

Have now confirmed that there were no recent changes to the 280 rem case

http://www.saami.org/PubResources/CC_Dr ... 0Rifle.pdf

Interesting thoughts but I have measured and shot several belted mags that had more headspace without a problem. I have used the Nosler brass in three different AIs without a problem, Rem 700, Ruger No. 1, FN Mauser action. I just measured the headspace on an unfired Nosler case and compared it to a three times fired case, neck sized only, case from the FN action. The unfired case measured case was 3.173 and the 3x fired case measured 3.182, a difference of 0.009". Since I can't use the same headspace gauge for unfired 280 cases to compare them to formed 280 cases from the same lot I can't give a reliable comparison but I tried two different methods. Using the AI gauge for an unfired 280 case gave 3.122 and 3.182 fired, Rem cases. Using a 280 headspace gauge, again the same Rem cases. The unfired was 4.100 and fired was 4.150. Never had case seperation when making AIs from the Rem cases or by using the Nosler 280AI cases. Be interesting to hear Nosler's comment.Rick.

Can this be attributed also to variation in primer pocket depth. Saami spec for a large rifle primer pocket depth range between .128"-132". I use Sinclair's pocket uniformer when uniforming my primer's pocket. My average primer pocket depth measured .127 which is .001 less than SAAMI spec. I measured 3 different brands of primer and I got 3 varying result. Winchester measured .122 at the cup and .125 if you include the anvil. The CCi measured .123 at the cup and.126 at the anvil. The Federal match measured .125 and there's no anvil protrusion.

What these tells me is that, depending on the brand of primer or brand of brass you use, the primer will always seat deeper into the pocket. Now if your brass has the max spec of .132" and you happen to use Winchester primer that has .122" cup, you gonna ended up with a clearance of .010". That definitely will have the same result as you described when using Nosler brass on a standard Ackley chamber.

I have 3 Ackley rifles. When fire-forming brass, I always load the round 10% below the starting load. I seat the bullet far enough to make sure the bullet engage the rifling and allow the bolt camming to push the bullet the rest of the way. In this way, I eliminate any headspacing issue.

rick smith":352jwju3 said:

Interesting thoughts but I have measured and shot several belted mags that had more headspace without a problem.

Click to expand...

The difference with a belted mag is that the belt will stop the forward movement and hold the primer in its pocket. So you can have a belted case that has .004" headspace but has .020" or more gap at the shoulder. Typically in all the belted mags I reload for the gap at the shoulder is from .017" to as much as .038"




By contrast in an unbelted case the shoulder is the point that stops forward movement and that defines headspace. You can not have headspace over ~.010" without getting into problems.

There was some further information on another forum that the reason is that some Remington factory loads for the 280 Remington caliber had variances in the case head to neck/shoulder junction as much as .007" so they shortened the headspace to allow for this poor quality control on Remington's part. Now that makes as much sense as letting Barney Frank, Chris Dodd and Chuck Schumer be in charge of fixing the FannieMae/FreddieMac situation! They cause it and now they decide how to fix it by boogering up everyone else rather than fix their quality control? Just throw away 50 years of gunsmithing?

Just think of it this way. For 50 years there have been 280 Ackley chambering, fire forming and shooting with no problems. Now we forevermore have two different 280 Ackley Improved chamberings and someone could run into a problem like I did with flattened primers and maybe worse, that creates a problem where there wasn't one!

It seems there is quite a variance on the Nosler brass if others are getting .009" headspace and I am getting .017". If so then Nosler has a quality control problem. The only other explanation for that would be that Hart reamed the chamber wrong, what are the chances of that?

Desert Fox":3usa8sty said:

Can this be attributed also to variation in primer pocket depth. Saami spec for a large rifle primer pocket depth range between .128"-132". I use Sinclair's pocket uniformer when uniforming my primer's pocket. My average primer pocket depth measured .127 which is .001 less than SAAMI spec. I measured 3 different brands of primer and I got 3 varying result. Winchester measured .122 at the cup and .125 if you include the anvil. The CCi measured .123 at the cup and.126 at the anvil. The Federal match measured .125 and there's no anvil protrusion.

What these tells me is that, depending on the brand of primer or brand of brass you use, the primer will always seat deeper into the pocket. Now if your brass has the max spec of .132" and you happen to use Winchester primer that has .122" cup, you gonna ended up with a clearance of .010". That definitely will have the same result as you described when using Nosler brass on a standard Ackley chamber.

I have 3 Ackley rifles. When fire-forming brass, I always load the round 10% below the starting load. I seat the bullet far enough to make sure the bullet engage the rifling and allow the bolt camming to push the bullet the rest of the way. In this way, I eliminate any headspacing issue.

Click to expand...

No, primer pocket depth and seating were just fine. I use Fed215M's which are very consistant and have a very educated thumb that tells me the primers are just below flush.

If you seat into the lands then you have not necessarily removed your headspace condition. If you have a lot of bullet grip or crimp then it is possible. Consider this, the firing pin hits with quite a bit of force (will have to look it up but I think it is over 30 pounds) which may seat your bullet further and you have headspace. Also the primer ignites and is like a mini charge pushing against the inside of the primer pocket trying to exit through the flash hole pushing the case forward, just like the big charge pushing against the rear of the bullet but much smaller. That will seat your bullet and you have your headspace again. Many say that this primer ignition actually sets the shoulder back a few thousands before the pressure expands it to fit the chamber again.

You can negate almost all headspace with a false shoulder which I have done and is a PITA but not by seating to the lands, IMO.

Woods, the SAAMI 280AI that you post from Gun Talk is pretty close to what Nosler has in the Manual # 5 which differs from what's in manual #6 which I think is the real SAAMI 280AI. I would assume when Nosler chambers a 280AI in the rifles they sell the reamer would match the cases they sell. also think the standard 280AI that Gun Talk list is close to the 280AI listed in manual #6 outside of case length and I think they just got them mixed up.

I have to agree with Rick in that I own two my wife has one 280AI and Nolser 280AI brass chamber fine in both rifles and the chambers were cut from the same Manson reamer.

I would be curious to know if Nosler's factory ammo in the .280 AI would be off enough not to work in some rifles? I plan on picking up the Kimber .280 AI when it comes out and will reload so it won't be an issue for me but others who don't reload may have some trouble. Just a thought.

All of you are heating my head. I thought I knew a little bit. Forwarded this thread to my son who is the mechanical engineer in the family. Maybe he can explain it to me. Keep it going. I have two Rem 700 long actions I need to do something with. 280AI seems to be a good choice. One for me, one for my son. How can it get better?

Here is what Dave Manson of Manson Reamers has to say:

From the reamer/headspace gage maker's point of view, SAAMI standardization of the 280 Ackley Improved has created problems. Mostly, it's a matter of making sure folks are informed about the change, proper fireforming--if they want to go this route--and which ammo to use in which chamber.

Ackley's intent, with rimless, shouldered cases, was to headspace the improved chamber so that the un-improved parent cartridge could be loaded and safely fired in it--the parent round was held between the breechface and the neck/ shoulder junction of the improved chamber. He advised that the breech-face-to-neck/shoulder junction in improved chambers be held some.004" to .006" shorter than in the parent chamber. Traditionally we, and other reamer makers, have done this, grinding reamers with a MINIMAL RADIUS at the N/S junction for more positive headspacing during fireforming.

Nosler/SAAMI shortened the traditional 280 AI headspace another .014". Additionally, the radius at the N/S junction was specified at .060" +.025". This was likely done because it's very difficult to form 40-degree shoulders with small radii--they're supplying fully formed ammunition, remember.

What does this mean for the owner of a 280 AI?

First, if you have one headspaced the traditional way, don't buy Nosler ammo unless you want to see evidence of excess headspace and risk case separation--its shoulder location guarantees at least .014" excessive headspace. When you need new cases, fireform them from 280 Remington brass.

Second, if you have a SAAMI-spec chamber, you can buy Nosler ammo OR fireform 280 Remington. The N/S junction on the SAAMI chamber IS .014" closer to the breech face, but the .060" radius at this points provides a little more room to accomodate 280 Rem ammo. You may feel a little resistance as you turn down the bolt handle, but it will go and the case will be held securely during fireforming.

Finally, re-loading. Don't use dies made to the old spec to re-size cases fired in SAAMI-spec chambers. The few re-size dies I checked that were made to the "old" spec would not reach the shoulder of a case fired in the SAAMI chamber.

You CAN use SAAMI-spec dies to re-size cases fired in old-spec chambers, but be sure to set the die so it barely touches the shoulder of the fired case. DO NOT set the die so it bumps the shellholder when the ram is up--you'll introduce excess headspace or crush the case.

There are different versions of the 280 AI out there, so this commentary doesn't apply to everyone. If anyone has questions about his specific rifle, I'm willing to try to answer them.

Dave Manson
1-810-953-0732

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Now that I know I can deal with it but I do still think if was irresponsible of Nosler to sell 280AI cases without notification.

:shock: I never realized there were two different 280 AI versions out there!! I wonder if the .280AI ever becomes a mass produced cartridge which standard will be the one accepted or official? The real .280 Ackley Imp or the Nosler/SAAMI .280 AI?

It will be the SAAMI version without a doubt and the only down side to this is if you have an older chamber. If you talk to any rifle manufacturer out there and ask them how they are going to ream the chamber they will all say "to SAAMI standards". You will have to specifically ask for the older version but why would you? The new SAAMI chamber will fire all cases and loads albeit with more of a crush fit on 280 rem cases and loads and a little less powder capacity.

My 280 AI is based off the 280 AI spec and R-P 280 Rem brass.
She shoots well and I am a happy capmer.

JD338

JD338":3eyyd0ih said:

My 280 AI is based off the 280 AI spec and R-P 280 Rem brass.

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That is the same setup I am leaning to as well, Jim. I like the higher case capacity of the original Ackely version. I just don't understand why Nosler, or anyone for that matter, would change the dimensions on something that worked perfectly. Perhaps I am showing my ignorance but was the SAAMI standard possibly a result of error in measurement?

No, based on the provided information, it was based on Remington Monkeying with things a few years back. Since Remington is a "sporting arms manufacture", and P.O. Ackley the thousands of smith who have chambered that Ackley these past 40 years are not, Remington, got a vote, and they did not. Since Nosler was making their brass to the only accepted industry standard, I'm nor really suprised they did not put a warning on the box. After all, they did got throught SAAMI, and everyone with a vote agreed upon this as the standard.

Well, I will be doing some load development here in the next couple of days using Nosler Brass. Not sure where PTG base their reamer dimension were. We'll find out do we.

I'm not sure there is a difference in anything except the way the round was measured...it "seems to me" that people are getting a little confused and not factoring in the fact that the old gauges had 17 degree shoulders and DID NOT headspace on the shoulder...the used the 280 Rem shoulder angle, which insured that 280 Rem ammo would headspace properly...off the neck/shoulder junction.

SAAMI/Remington/Nosler decided to make the gauge with 40 degree shoulders...which headspace off the .375 datum line (down on the shoulder)...anybody got the tools to measure and see if the neck/shoulder junction is .014" above the .375" datum line on the shoulder?

Well, when you check the drawings from SAAMI and the Traditional drawings for the Ackley Improved you find that indeed there is a numerical difference between the two drawings of .014″. The problem stems from reamer makers applying a datum line to the Traditional Ackley drawing at the .375″ diameter on the shoulder, this is not where the datum line is on a traditional Ackley.

The drawing calls for a 40 degree shoulder, but the datum measurement is based on the traditional 17 degree gauge. In other words the systems of measuring are mixed. Ackley used the junction of the neck and shoulder to headspace his Improved chamber, not the datum line along the shoulder.

Hence we end up with a headspace length of 2.1542″ on the Traditional drawing. I measured this length on my cutaway chamber and guess what, that is the length to the junction of the neck and shoulder. Thus headspace matches the drawings correctly.

The 40 degree SAAMI gauges are made to the industry standard, datum line method. So the drawings are correct, the datum line is at the .375″ diameter along the shoulder. The length called out for this gauge is 2.140″, which appears to be .014″ shorter than the Traditional design.

What we have is two different methods of measurement. However they achieve the exact same result.

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There are two reamers, gauges, etc because some makers are measuring to a different spot...the neck/shoulder junction or the .375 datum line...Ackely used the neck/shoulder junction...SAAMI uses the .375 datum line...the datum line (down on the shoulder) is .014" closer to the head of the case than the neck/shoulder junction....or at least thats the way it seems to me.....I could be wrong.

I also want to add that if all this is in fact true...and the SAAMI/Nosler round is .014" shorter at the shoulder...it is just further proof that Remington could, and will, tear up an anvil with a Q-tip.

Bad choice...following Remingtons lead on this...just look at their history with the 280 Remington, they loaded it weak from the start, they re-named it it a couple of times...the round could have been a lot more popular than it is had they made good decisions then.

I would not have trusted them to do any better with the Ackley version...

That said...I don't guess there's any real damage done...the .014" in capacity won't be missed (not enough to matter)...but it sucks that all the confusion had to play out, and that most folks seem to be blaming Nosler.

Maybe Nosler should try to get it renamed "284 Nosler" :mrgreen:

Gentleman I am not near as wise as any of you. I read about this problem some time ago so I asked the smith that built my rifle. He advised me that I could fireform or use Nosler brass. He advised that I would not have any trouble.
I have 50 new Nosler Brass & have purchased two boxes of Nosler factory 140gr trophy grade for the break in. Why would the new Nosler brass not fireform to my rifle.

Blessings,
Dan