Looking at both as a long range deer rig and was looking for some opinions. It might go into a Ruger 1 or be used in a switch barrell M77 that is currently a .35 Whelen. Regardless of which platform I use I would like to keep the case size at about '06 size and no belts. I am open for other suggestion like the 264 hawk but have eliminated the .270 only because everyone has one.

if your looking for longrange deer rifle i'd lean towards the 280AI, just for the heaver bullets. i have a rifle i just built as a 6,5/06AI and i love it! low recoil and a tack driver, but i built it for yotes way way out there.

For my 2 cents I would go with the 6.5. I have my own versions of both. I use a 280 case and improve it. Moving the shoulder forward. With a 140 in 6.5 your SD is the same as a 160 in 7mm. At any reasonable distance the 6.5 gives up nothing to the 7mm. And has lighter bullets for coyotes. When I first designed mine I took a 280 from 280Rem to 280 Ack to 7mm JRS(moved shoulder forward) to mine (it has more capacity than the hawk). Each step gives some increase. Since you can buy off the shelf dies for the 6.5-06 AI I would go with it and not look back. If you need something the 140gr can't handle then you have your Whelen. If you simply want something different to discuss around the campfire then any of them will work.

As to your switch barrel idea. Sounds good on paper but... I have a MKX with 3 barrels. I can swap them but it isn't a 3 minute deal. If you are talking about doing it with the action in the stock then you have to have a barrel nut etc. It can be done. Or maybe a rear entry action wrench and then grab the barrel in front of the stock. In my case I pull the action and swap barrels. All three have the same contour and the scope repeats it's settings (close). So I can just dial in and get close. However in my case The accuracy is not as high as if I work up a load and leave the rifle together. I give up .5-.75 MOA of my accuracy potential.

How about a 6.5, .270, or a 7mm Gibbs?

Ramrod-Its pillar bedded in a Wildcat composite stock and will hold its zero when torqued to 60 lbs so I'm not worried about leaving it in the stock for the switch. I dont plan on swapping back and forth a lot so it would be no big deal to confirm the zero at the range

Snake-What is the 6.5 Gibbs based on and does it get anymore speed than the 6.5-06AI?

Thanks guys I appreciate the responses

Todd,
The Gibbs is based on an improved 06 with the shoulder moved forward. Take an 06 case. set the neck to .25" blow it out to .455 at the shoulder and use a 35deg neck. As an example 140gr with a 26" barrel you can reach 3126fps. My case uses a 280 case and has a .28" neck .458 shoulder at 40deg. I can send you a copy of the 6.5 Gibbs data and a copy of my Accuload tech sheet for my 280(same case but .284). Send me an email if you want the data.

The A.I. case increases powder capacity a bit over 2% and the gibbs case nearly 7% (based on the .270 cal of each)

I've actually measured the change in a 280. AI gave 4.1% the Gibbs gave 10.2% my case gave 11.4%. When I plot the Gibbs and my case out the only real difference is the 35 vs 40 deg shoulder and longer neck. In the same length magazine there is no real difference.

Todd C,

I just sent two rifle out the door to customers in both of these calibers.

The first one, the 6.5-06 Ack Imp, was built into a long range varminter using a heavy tactical style stock and heavy contour Lilja barrel of 26.5"

The second was a Sako sporter that was rebarreled to the 280 Ack Imp, again with a 26.5" Lilja.

I just received reports from both customers and here are the results as far as accuracy and velocity from the testing they have done so far.

The 6.5mm-06 Imp
140 gr A-Max topped out at 3200 fps. Top accuracy was at 3160 fps with .4" average five shot groups at 100 yards.

280 Imp
160 gr Accubond topped out at 3125 fps with its best accuracy load at 3075 fps which averaged .6" for five, five shot groups at 100 yards.

With these very long bullets, group size will grow very little out to 300 yards as it takes about 200 yards fro the bullets to "go to sleep" and fight off the effect of the rifling and fly stable on their own.

The best thing about these rounds is that both customers reported 10 shot groups running under 1 moa using virgin brassed fire forming loads.

This is a real benefit when hunting abroad if you loose track of your ammunition. All is not loast, factory loads can be used and with the chambering technique I use, are extremely accurate as well. The factory ammunition will not get teh velocity obviously but they will still be plenty potent for all deer hunting.

In my opinion, for deer, it would be a toss up, they both run right on the heels of their belted magnum brothers with less recoil and longer barrel life.

If you ever plan to add elk to the equation, I would strongly recommend the 280 Imp.

If you will only be hunting deer, the 6.5 is very hard to beat with the 120 gr Ballsitic Tip at 3350 fps. Very flat shooting and plenty of power for any deer.

Course the 140 gr Ballistic Tip at 3250 fps out of the 280 Imp would be very good as well.

Bullet sellection comes down on the 280 side but not by much.

Take your pick, but I would stay with one of the Ack Imp roudns to keep the ability to shoot factory ammo. This is not something you can do with the more exotic wildcats and the increase in performance is very little over the Ack Imp.

Good Shooting!!!

50

If it was only a deer/antelope rig, I would probably go 6.5 even though I am a big fan of the .280/.269AI. If you thought you might want to hunt elk once, then go up to the .280AI for the heavier bullets.

Heck make a 270 Improved. Nobody has one of those. Then you can form brass from 280 Rems and have most of the work done.

The 6.5-06 is not standard so there would be no factory back up ammo.

As to one caliber over the other all those will do it. Bigger does hit harder however.

Actually A square made factory ammo for the 6.5-06 and there's a european version, but they're not what I would call common. FWIW - Dan