Home Forums Hunting & Shooting Long Range Hunting 280 ackley improved

In africa last september, a red hartebeest fell one shot at 500 meters (550 yards for metrically impaired). About 5 minutes after I also clean missed a shorter shot at same animal at 350 meters across an open valley . but that was when he moved same time I shot. THere really was no way to get across a valley with three inches of grass cover... and we had stalked a mile plus for the shot...

it was in the words of the PH: "as good a shot as any this year".

140 NAB, 62 grains Re22, CCI 200, Nosler ackley brass. chronos at 3200 mas or menos.

Interestingly, the 7mm Weatherby tops out at 3197 in the same manual.

I think it has about the same physical case capacity gain over the 7RM as does the 280 over the AI...indicating pressure differences are the issue, as 3-4 grains in a slightly larger case does not net that much. The representative RL25 loads show a spread of 6 grains...

Would suspect same for the AI vs 7RM comparison with the 160s.

The 7RM to the 280AI is a DD to D-cup comparison, both impressive but noticeable differences are perceivable.

The AI may not have much over the 280 or the 270 but if long was my concern, Nosler makes brass...

FWIW...

If you look a little more closely you will see the .280 Rem AI loads are from a 26� barrel while the 7mm RM loads are from a 24� barrel. Subtract anywhere from 50fps to 80fps, perhaps more, from the .280 for a valid comparison. You will also have to note that different powders were used, making the difference in charge weights pretty much an invalid comparison.

Next, for a more apples-to-apples comparison, let�s compare the same powder using 160g bullets. Since I have and use both and Nosler lists both for both cartridges, let�s use Reloder 22 and IMR7828.

.280 Rem AI
3035fps, 60.5g Re22, 101% Load Density
3043fps, 61.5g IMR7828, 101% Load Density

7mm RM
3015fps, 64.0g IMR7828, 85% Load Density
3058fps, 63.0g Re22, 85% Load Density

If we subtract 75gfps from the .280 velocities to adjust for the shorter barrel, it looks like this:
2960fps, 60.5g Re22
2967fps, IMR7828

If we look at pressure, Hodgdon lists the following:

.280 Rem AI
2849fps, IMR7828, 61,300PSI

7mm RM
2868fps, IMR7828, 58,200 PSI

Looking at all the Hodgdon 160g loads for the two cartridges, it is readily apparent that the .280 Rem AI is running slightly behind the 7mm RM in terms of velocity but at significantly higher pressures. Put another way, loading the 7mm RM to the same pressure as the .280 Rem AI will yield higher velocities.

I don�t know what SAAMI MAP is for the .280 Rem AI or if there even is a SAAMI standard for that cartridge. I do know that its 61,000 PSI for the 7mm RM. I have Rugers chambered in both the 7mm RM and .300 WM and see no reason not to load the 7mm RM to the 64,000 PSI level of the .300 WM. When that occurs the 7mm RM easily outdistances the .280 Rem AI.

By the way Vihta Vouri lists the 7mm RM at 3114fps with a 160g bullet and N560 powder, the same powder used for the Nosler .280 Rem AI load you referenced. That�s 3114fps for the 7mm RM, again from a 24� barrel, compared to an estimated 2949fps for the .280 Rem AI with a 24� barrel. Douing the math, that�s a difference of 154fps.

The .280 Rem AI is a good cartridge, but it can�t keep up with the 7mm RM when other factors like pressure and barrel length are equal.

I noticed the 26" barrel on the 280AI after I posted.
Do you think 75fps is an accurate decrease though for matching the barrel length?

According to this formula a 30-06 case loses 39 fps when shortened from 26" to 24". Wouldn't a .280AI be affected closer to that number?

http://www.loadammo.com/Topics/October05.htm

I listed two different powders because they were listed as the top velocity charge for each cartridge. I wasn't sure comparing same powders would be fair since they are different cases. However I agree that comparing the charge weight on two different powders is misleading, I was really just using a little hyperbole there to have a little fun.

If the formula I referenced is correct, it's still not that much difference between the 7RM and the 280AI when one is discussing long range. At least to my thinking. Sure the 7 RM will top out a little higher, but is that small amount enough to pass on a shot at any distance comparing one to the other?

This is at 500 yrds.? Not 100 yrds.?

The numbers I�ve seen indicate an extra inch can add anywhere from 20fps to 50fps to a load � I simply picked a number in the middle. The article you reference shows a couple of things that make sense, 1) the higher the velocity, the greater the difference, and 2) the shorter the barrel the greater the difference. If you don�t like 75fps, the number I chose, the article you reference shows 48fps for a 7mm RM, 24� to 26�, with MV of only 2885fps from a 24� barrel. So, to keep the math easy, let�s call it 50fps instead of 75fps.

That means the adjusted ,280 Rem AI 160g/N560 load would run 2985pfs, still 129fps slower than the Vihta Vouri 7mm RM 160g/N560 load. If we assume a BC of .31 (160g AccuBond), the 7mm RM has a 75 yard advantage in terms of velocity and energy.

The original question was :

to which I answered �Nope, got a 7mm RM that will do everything a .280 Rem AI will do, and then some.� The fact is that the 7mm RM will beat the 280 everyday in all weights and when it comes to 175�s its 2970fps vs 2828fps per Nosler 6th, a 142fps difference before adjusting for the longer .280 Rem AI barrel and 192fps after doing so (using 50fps as the adjustment factor).

I�m not claiming the .280 Rem is a bad cartridge. Nor am I claiming the difference in capability will make a big difference in the field, as in most cases it certainly will not. Neither one would be my choice for high volume long range target work - I�m building a 6.5-06AI for that - but for the occasional long range hunting shot and using the best loads in each, the 7mm RM will add about 75 yards to what the .280 Rem AI can do in terms of velocity and energy.


Whether that extra 75 yards is important or not is up to the individual shooter. Of course the 7mm RM can always be downloaded to .280 Rem AI velocities...

Most of the 280AI data in Nosler #6 is simply reprinted data from #5, (24" barrel). The only data they re-shot with the 26" tube is that for the 140's and 160's, (I presume because the Fail Safe bullets were dropped from production.)

It is primarily the 160's that are under discussion.

Since there isn't alot of factory chamber 280AI pretty hard trying comparing 7mag to 280AI. My 280AI dosen't have a barrel that match either Hodgdon or Nolser data I guess on paper data you might do it.

The .280 AI is a SAAMI cartridge (submitted by Nosler a couple of years ago) and the pressure limit is either 64,000 or 65,000 psi, I can't recall right now.

The SAAMI limit for the 7mm Remington Magnum is 61,000. This is because the 7mm RM tends to show wider pressure variations with any given load than many other cartridges. For instance, in a typical .30-06 or .300 Winchester Magnum load the range of pressures in a 10-shot string might be 5000 psi. But a 7mm RM often shows a 10,000 psi variation between individual shots in 10-shot string.

SAAMI maximums are not just based on an average, but individual shots. They set the average at a place where any individual round won't be over a certain level--the reason the average SAAMI pressure limit for the 7 RM is only 61,000.

Primarily, but you moved to 175's and still subtracted barrel length, so I thought it might be worth pointing out that not all the #6 data was shot from the 26" barrel.

OK, here�s data from Nosler #5 for the .280 Rem AI and the 7mm RM, all from 24" barrels. Draw your own conclusions.

140g @ 3340fps, 67.5g Re22, 7mm RM
140g @ 3196fps, 63.0g Re22, .280 Rem AI
===============================
+ 144fps, 4.5g powder, 7mm RM

150g @ 3248fps, 63.0g IMR4350, 7mm RM
150g @ 3107fps, 63.0g IMR7828, .280 Rem AI
===============================
+141fps, same powder charge, 7mm RM

160g @ 3112fps, 79.5g H870, 7mm RM
160g @ 3058fps, 63.0g Re22, 7mm RM (Since H870 is no longer available)
160g @ 2963fps, 61.0g N165, .280 Rem AI
===============================
+149fps, plus 18.5g, 7mm RM (H870)
+95fps, 2.0g powder, 7mm RM (Re22)

175g @ 2970fps, 62.5g Re22, 7mm RM
175g @ 2828fps, 58.5g IMR7828, .280 Rem AI
===============================
+142fps, 4.0g powder, 7mm RM



Another comparison that could be made from Nosler #6:

160g @ 3046fps, 61.5g Re19, 7mm RM
160g @ 3045fps, 59.5g N560, .280 Rem AI
===============================
+1fps, 2.0g powder, 7mm RM

Or, subtracting 50fps from the .280 Rem AI velocities to adjust for barrel length:

160g @ 3046fps, 61.5g Re19, 7mm RM
160g @ 2995fps, 59.5g N560, .280 Rem AI
===============================
+51fps, 2.0g powder, 7mm RM

The point here being that you do not need to burn and extra 12.5g powder in the 7mm RM if matching .280 Rem AI velocities is desired.

Vihta Vuori lists the 7mm RM at 3114fps with a 160g and 73.9 N560 powder, for 69fps better than the 3045fps .280 AI load you cite, albeit with 14.4g more powder in this particular case. Again, the 7mm RM will do anything the .280 AI can do, and then some.

While I�m not claiming that 69fps is any great difference, especially at 14.4g additional powder, the loads above show three 7mm RM loads producing an additional 140fps+ with 0-4.5g powder using bullet weights of 140g, 150g and 175g. At 160g the difference was only 95fps but the additional powder charge was only 2.0g Re22 as well.

It only makes sense to assume your comment about having to burn an extra 12.g was to suggest the 7mm RM was less economical than the .280 Rem AI. I�ve already shown it isn�t necessary to burn that much powder to get better performance, but what about the rifles themselves?

The 7mm RM is available as a standard chambering from most manufacturers and at any given time there is a wide variety of used 7mm RM available due to its long popularity. The .280 Rem AI a different story, however, and Nosler is the only company I know that is chambering production rifles for it. As a result a good 7mm RM can be had for as little as $300 while the Nosler comes in the �Custom� model with a list price of $3,995.00 or the �Custom 48� model with a list price of $2,795. Gunbroker currently has one active auction for a Nosler Custom 48 in .280 Rem AI with a �Buy now� rice of $2,595.00. One could, of course build a custom .280 Rem AI rifle for much less, but the chances of finding a used one are pretty slim.

Let�s see... $2595 - $300 = $2295. For the economy minded, like yourself apparently, that�s a pretty steep price to pay to save 12.5g of powder or about $0.04 per shot at current powder prices. One would only need to shoot about 59,776 rounds in a Nosler rifle to break even...

How about factory ammo availability? 7mm RM ammo is available everywhere, for as little as $19 a box. Ammo for the .280 Rem AI is pretty much limited to Nosler at $55 to $58 a box with only two loads available, a 140g AccuBond and a 160g Partition. Of course with factory ammo you only care about the cost of the box and the 7mm RM wins by a landslide.

Shoot the .280 Rem AI to save money? Surely you jest...

Coyote,
Good post. Here is some recent "real world" velocities from some load development and work at the range in the past week.
280AI 24" Barrel Model 28 NULA. 62.9gr N165 140 TTSX 3140 fps.
7MM Rem Mag Sako 75 24" Spencer 71gr IMR 7828 140 TTSX 3320 fps.
The 7MM is throated a little deeper than most and can stand a little more powder. Looks like the 140 in a 280 AI slows down at least 50fps for the 2" of barrel (26" Wiseman) in Nosler #6. Will be working with both rifles and will have more data next week. Don't think the Ackley is a bargain in any sense compared to a 7MM RM except that it burns a little less powder and is a neat looking cartridge.
Thanks for the data in your post

Dave

In addition to nosler, cooper, dakota and kimber also chamber rifles in 280AI.

RaceTire/Coyote: Good posts.

A lot of this conversation leaves a huge gap because no one knows what pressures they are actually running,and if we add in the tremendous variations in barrel/chamber/throat dimensions,comparisons between the two cartridges becomes increasingly cloudy.

At the end of the day,over the broad range of rifles,and keeping things as equal as possible the 7RM will always be the faster cartridge,and easier to get higher velocities with because it HOLDS MORE POWDER.

I can build,tomorrow, a 7RM that will show the velocities obtainable from a 7 Weatherby(the 280 AI boys sorta leave that cartridge out of the comparison mix because it easily outruns the 280AI);yet the 7 RM has about the same capacity as the Weatherby,and throated the same, will do what the Weatherby does,......which is,be faster than a 280AI,and the margin will increase as we get to heavier bullets.

Conversely, I can build a 7RM so dumbed down that a 280 AI will likely beat it.

I'll repeat what I said before;someone should take a 280AI,work up to max at a given pressure level,and then rechamber to 7RM and load to the same pressures. I suspect they'll find that the 7RM is faster at the same pressure levels,simply because it holds more powder.

Contrary to what many may think, the 280AI is not spot news,has been around for decades now,and a couple of friends of mine messed with it years ago,and reported results. They don't use it today and think the hoopla over it is sort of funny.I never got involved with it due to having loaded,chronographed and hunted with the 280 and the 7RM since the 70's,and considered the 280AI not worth the bother,the same way I don't understand the 25/06 AI while we have the 257 Weatherby.In both cases, the magnum hulls give you the real improvement over the standard cases without loading to the gills,and still keeping powder consumption and recoil at manageable levels.

Good though the 280AI may be(it IS a good cartridge), if I'm gonna run around with a 30/06-length action and a 24" barrel,I'll take the 7RM everytime.

While not in the cards right now I have toyed with the idea of building a 280 AI. I imagine it comes down to how toying you want to do when you can buy an off the shelf round that will do the same thing!

Thanks - I didn't know anyone else was making production .280 Rem AI rifles. Here are the prices I found:

$1,595 and up, Cooper
$1,312, Kimber

Could not find a .280 Rem AI on the Dakota web site using the "search by caliber" feature.

Still, for the economy minded, the 7mm RM is the better choice.

Bob,

Stop making sense,it is messing up all my preconceptions.

I have a custom 280 AI,and a custom 7mm Weatherby,both on Remington actions with 24 inch Barrels.

I can get 160 grain bullets to 3150 fps in the Weatherby,I can get 140 grain bullets to about 3200 fps in the 280 AI.

So there is no question a Magnum(properly throated) is more gun.

But here is the rub,I need a muzzle break to make the magnum as comfortable to shoot as the 280 AI.

The 280AI does gives us very good long range performance with a recoil level that is pretty much in the class of a 30-06.

The 280 AI tends to be super accurate as well,perhaps since probably 90% of the rifles out there in 280AI have custom barrels and chambers. Whether they would be just as accurate in 7mm Mag is open to debate.

As a practical matter most people are better off with the 7mm Rem Mag,rifles,brass,and ammo are generally avaiable anywhere that sells any of the above.

But a guy who handloads and wants a super accurate custom for long range hunting of everything from antelope to elk can do quite nicely with a 280 AI.

It falls in the tiny gap right between a 270,a 280, and a 7mm Mag and it is different in a cool sort of way. What could be better than that?

Britt: Oh I never said the 280 was not good;clearly that would be a bit intellectually "dishonest" Since I like and have used cartridges on either side of it,I have a pretty fair idea of its' capabilities.

I'm taking issue with the narrow issue that it is as fast as the magnum-jugged 7mm's; that's all.

And when making a choice between it and say a 7 RM and a Weatherby,I'll just take the bigger case,get the fractional increase in vel,and not worry about whether or not I'm leaning on things to get there.

There seems to be persistent myth that runs through the noodles of rifle loonies, here and elsewhere; that a smaller case can "equal",all things being the same , the potential velocity of a larger case.This is simply untrue.Many times the smaller case can come close, or pressures can be run up in the smaller case so that it "looks" as good...but IME across the board,it can't be done.

IME the 7RM put up in a good rifle,and given the TLC heaped on most 280AI customs, will be just as accurate. I generally find the 7RM a comfortable rifle to shoot,which is one reason I've been a 7mm fan for many years.

When I built my latest 7 cal backpack rifle, I went with 280AI. Why? Because I got a good deal on a very nice stainless M700 action with a standard bolt face. If I had found a magnum action first, it would have been a 7mm Wby. They're both great cartridges.