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280 ack imp 40 degrees vs Nosler brass

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Old 05-02-2013, 11:17 PM
Junior Member
Join Date: Nov 2010
Posts: 17
Re: 280 ack imp 40 degrees vs Nosler brass

Originally Posted by dporter99 View Post
Dumb question: if we shoot a SAAMI nosler factory round or reloaded new brass through an original AI chamber, won't it fireform to the original (0.014 longer) chamber and be fine for remaining reloads?
Not a dumb question. Yes it will fireforn to the new chamber.....But, you may have headspace issues.Primers backing out,then flattening, shortened case life etc. You may get by with seating your bullets into the lands to get the proper FF. The best way would be as Eddybo suggests by creating a false shoulder to give a crush fit.
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Old 05-03-2013, 10:16 PM
Junior Member
Join Date: Sep 2009
Posts: 16
Re: 280 ack imp 40 degrees vs Nosler brass

So can't I just purchase the Nosler 280AI saami factory loads and shoot them to fire form a case to my chamber? will it just blow out the brass to perfectly fit my non-saami chamber? sorry again for the rookie questions!
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Old 05-04-2013, 06:55 AM
Platinum Member
Join Date: Dec 2011
Location: Michigan
Posts: 1,081
Re: 280 ack imp 40 degrees vs Nosler brass

Originally Posted by dporter99 View Post
So can't I just purchase the Nosler 280AI saami factory loads and shoot them to fire form a case to my chamber? will it just blow out the brass to perfectly fit my non-saami chamber? sorry again for the rookie questions!
And that, sir, is the real question here. This thread started with evidence that the "original" PO Ackley chamber and the SAAMI chamber are actually the same, and the reported 14 thou difference in case length was incorrectly determined by where the measurements are indexed. Members came in with experience with Nosler 280AI brass: some agreed, some said they measured 6 thou, some said it was 14 as reported. I think it is fair to say there is no concrete resolution to this (at least in my mind).

To directly answer your question, if indeed your chamber was 14 thou longer to the shoulder than 280AI factory brass, firing it will fit it to your chamber. But keep in mind, that material needs to come from somewhere to allow it to stretch. By necessity, stretching the case longer will thin the case wall. The hope is it thins uniformly. Worst case is it localizes near the case head, and after a few loadings you have a potentially dangerous (or at least scary) situation. To use your quote above, you might eventually "blow it out".

This is my opinion and not science: 14 thou, if real, is beyond my comfort level for excess headspace. When in doubt, I err on the side of caution. I will continue to fire-form from 280 brass, or I will measure 280AI factory brass headspace relative to my fireformed brass before using it.
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Old 06-23-2013, 01:27 PM
Junior Member
Join Date: Sep 2009
Posts: 16
Re: 280 ack imp 40 degrees vs Nosler brass

Looking at the RCBS dies. which one should be longer to the shoulder, the 280 AI SAAMI (17001) or 280 REM IMP 40 (56266)? Cannot find specs or dimensions within the RCBS website... The more I think about this, the more confused I get!
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Old 07-15-2013, 11:12 PM
Junior Member
Join Date: May 2012
Posts: 12
Re: 280 ack imp 40 degrees vs Nosler brass

I started reloading last year. Bought a bunch of books, spoke with some experts, etc. I am not a pro. Just tried to take good notes and follow instructions. I have had a lot of fun. I have learned a lot and my guns are getting very good accuracy. I actually have a 7 MM shooting berger vld 168 going around 3050 fps that groups consistenly under .5 MOA! It is a Hill Country Rifle with a Lilja #5 barrell (24 inches) I bought it used with only about 100 rounds down the barrel.

I digress. My 280 AI is a 280 Ackley on a Remington 700 action. It has a 26" Shilen select match sporter barrel. It also has a Shilen trigger, Williams bottom metal, and HS Precision stock. Love the gun and the accuracy. Very reasonable kick.

I followed the advice from Ted (See below) and bought 100 280 cases from Nosler. I worked up a fire form load just using the virgin 280 cases. I used 168 grain berger vld, 54 grains of 4831 SC, Federal GM 210M, .015 from the lands that averaged only 2668 (remember, fireform load), but had a great 3.21 sd. I sighted in 4.3 inches high at 100 yards, to be dead on at 300. I had to use fire formed loads to hunt with, because I ran out of time to work up full power loads for the 280 AI.

My 16 year old son used the 7mm to shot a cow elk at 125 yards, trotting. He dropped the elk with a neck shot. Crazy, I know!

My 12 year old daughter shot a very nice (24 inch wide, tall) 3 point at 325 yards with the 280 AI, using the fire form loads. 1 shot. Dropped him!


Back to the question on Nosler brass....

This gun has the original AI dimension, not the Nosler specs. I bought 280 AI brass along with the gun. The first time I shot the brass, everything was fine.

When I reloaded for the second time, the reloaded ammunition had a hard time fitting. When I went to close the bolt, it was very difficult.

I called Redding. They told me to try a bunch of different tests. I found out my cases were bulging at the bottom.

I called the gunsmith that made the gun (Ted) and chatted with him. He told me, "Do not use the Nosler brass in your gun."

Your older 280 AI may work with the Nosler brass, mine did not (after the first shot).

These are my notes from my conversation with the gunsmith.

A. He doesnít own a nosler reamer! It has to be the 280 AI, old
B. He knew my problem right away!
i. You canít use the Nosler brass!
ii. If you use the Nosler brass, the case will bulge at the bottom!
iii. The Nosler, headspace shorter than the old Ackley, because of this, the case will stretch at the back, not the front!
C. If you use the Nosler 280 AI brass, need to fireform by jamming the bullet into the lands, so it keeps the case against the bolt face!
D. Fireform
i. He would recommend using the 280 brass. Cheaper, and easier to use.
ii. Put the 280 brass in the gun, there will be some resistance when you try to close the case.
a. The 280 AI is 4K shorter than the 280.
b. By using the 280 case, it forces the gun to stretch up front.
c. It will force the case back against the bolt face and make it stretch up front, not in back.
d. Pick middle of the road load with recommended powder, 4350 or 4831.
e. Many cases it is just as accurate in fire forming as it is after fire formed.
f. Donít jam bullet when shooting the 280
g. Middle of road, not minimum and not hottest.
E. Background information
i. Headspace on traditional AI is 2.144. Headspace on new AI is 2.130
ii. My case when fired are 2.135-2.137. That is why I am not bumping the shoulder back, the shoulder in my redding die is 2.144.
iii. When I shot the case, the case is not flowing forward, but backward, that is why I got the bulge!
F. As a rule of thumb, a max load of the parent cartridge is a starting load for the AI.
Example- 280 rem 140 gr 57.0 grs RL 19 is a max load but a starting load in the 280 AI. If the AI is correctly chambered, the parent cartridge will have a slight crush fit on the neck/shoulder junction of the case. This is where it will head space so you do not have to seat bullets into the lands.
G. The fireforming loads can be full pressure hunting loads.
H. One interesting advantage to Ackley's design is that factory .280 Remington ammunition can be used in case of an emergency. If you have to do this, the only thing you lose is a slight bit of velocity, but accuracy is still very good.
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