Winchester Model 70 .280 Remington upgrade to AI

Sid Post

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Jul 27, 2007
Messages
169
Location
Texas, USA
Hi Sid, I'm actually from Sydney Australia not Europe. The 280 Rem came out of the blue and a very recent acquisition. Brand new M70 Super Grade at a good price probably due of the unpopular calibre. I was surprised though when I could find 150gr Precision Hunter ammo in stock and at decent prices! Shoots it ok too. That sealed it - was never going to be an AI then plus the twist rate.

I haven't got any game in particular in mind. Always a fan of the M70 and after hunting Africa in 2019 with my M70 Kudu Custom 375H&H became an even greater fan! Ironic that the only animal on my list I missed out on was a Kudu. Kudu Services is what my gunsmith trades under.

Back to the 280Rem I'll leave it as is - it's a good calibre which becomes great if you hand load. If I need more speed I have a 7mm Rem. One pleasant discovery is the milder recoil compared to a 30-06. Not that the 30-06 is bad but you do feel the difference and it is just that "feel" so it's a personal opinion.

The 7x57 is great. Used my PH's rifle an M98 to take a Nyala and Warthog. So mild yet so deadly!

Hope you get to do your African trip. Well worth it.

Regards
JohnT

Rifle imports are a challenge. It's good to hear your M70 in Portugal found a good home in Australia! Those M70 CRF rifles make really popular options for African Safaris. You have your share of tough critters in Australia too! I've known a few guys that took some tough game in the outback over there.

Unfortunately, I've had some setbacks on the Safari front. After a shoulder rebuild, a hard-hitting 470NE double isn't really viable anymore, nor any of my big boomer bolt actions. Add a job layoff and the trophy fees for the big animals, not to mention the big 5, are out of reach right now. My little 7 Mauser or the 6.5x55 (6.5 Swede) and some smaller plains game are still a post-COVID dream. Both of those calibers are drastically underestimated and often overlooked by people in the USA chasing the latest boutique cartridges (Noslers, Ruger Compact Magnums, ...) that are all the rage on forums and in the gun magazines selling print ads and copy space these days.
 

Weatherby Fan

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Jan 10, 2011
Messages
635
Location
Maple Ridge, BC, Canada
I would rechamber to 280AI in a heartbeat, several factory ammo offerings now, Nosler, Hornady and Federal, good aftermarket brass available.
Definitely my favourite .284 cartridge and maybe even my favourite all round hunting cartridge.
I’m getting 3030fps with 160gr AB using 60.5grs of R26/210M primers, 1-9 twist 24” barrel.
 

jbo829

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Oct 5, 2017
Messages
212
Long ago I thought about doing the same to my 280 rem but in the end I opted to have the 5 rounds in the mag and the one in the chamber instead of losing one and not gaining much speed really to make it worth the while
 

john k

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Aug 7, 2020
Messages
100
Location
North Central FL
I would rechamber to 280AI in a heartbeat, several factory ammo offerings now, Nosler, Hornady and Federal, good aftermarket brass available.
Definitely my favourite .284 cartridge and maybe even my favourite all round hunting cartridge.
I’m getting 3030fps with 160gr AB using 60.5grs of R26/210M primers, 1-9 twist 24” barrel.
which other powders have you had good accuracy results with? I can not get RL 26 but IMR 4350 and H4831sc get me MOA with 160 Accubonds but not .5 moa I desire. Y rifle does not particularly like the 140 or 150 grain bullets. Twist is 1 in 9.5. Thanks
 

Bob Wright

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Jan 23, 2018
Messages
1,017
Location
Litchfield Park, Az.
Reloder 23 works well, but your twist will limit you to 140-150 class IMO. If you work in that bullet class, just need to run some ladder tests and compare powders/primers. My 8.4 twist will run 168's easily but the 9.5 twist is maybe 160 gr. max bullet weight, cup and core style. Got to try it to see.
9.25 twist in my 7 mag would stabilize the 168 VLD Bergers, but nothing else on the planet would shoot better in that gun. It's now been rebarreld to the 8.4 twist 280AI...
 

john k

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Joined
Aug 7, 2020
Messages
100
Location
North Central FL
Reloder 23 works well, but your twist will limit you to 140-150 class IMO. If you work in that bullet class, just need to run some ladder tests and compare powders/primers. My 8.4 twist will run 168's easily but the 9.5 twist is maybe 160 gr. max bullet weight, cup and core style. Got to try it to see.
9.25 twist in my 7 mag would stabilize the 168 VLD Bergers, but nothing else on the planet would shoot better in that gun. It's now been rebarreld to the 8.4 twist 280AI...
Thanks
 

Weatherby Fan

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Joined
Jan 10, 2011
Messages
635
Location
Maple Ridge, BC, Canada
which other powders have you had good accuracy results with? I can not get RL 26 but IMR 4350 and H4831sc get me MOA with 160 Accubonds but not .5 moa I desire. Y rifle does not particularly like the 140 or 150 grain bullets. Twist is 1 in 9.5. Thanks

I tried H4831sc, I had good accuracy but velocity wasn’t there in my rifle.
R23 should also be good to try.
 

C S Fever

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Joined
May 11, 2014
Messages
76
which other powders have you had good accuracy results with? I can not get RL 26 but IMR 4350 and H4831sc get me MOA with 160 Accubonds but not .5 moa I desire. Y rifle does not particularly like the 140 or 150 grain bullets. Twist is 1 in 9.5. Thanks
If temp sensitivity is not an issue R19 is awesome in the 280 and the 280AI. Used it for years in the 280 and in the AI about a year. My wife loves carrying and shooting my 280 ai
 

Bob Wright

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Jan 23, 2018
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1,017
Location
Litchfield Park, Az.
I tried Varget, H4831SC and RE23 in a 10 shot set of ladders.
The RE23 was about 150 fps faster than any of the other book loads for H brands.
I also found thru help here, in the 280AI RE23 really settled in with a Fed GM215M primer. A very steady predictable increase of ~25 fps per .5 grain charge increase.
 

FEENIX

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Dec 20, 2008
Messages
15,165
Location
Great Falls, MT
But with a long twist and short barrel 22", you won't gain a whole lot.
I am not here to argue but this is purely relative and deserves consideration. What is considered a significant gain?

.280 AI 100 FPS gain.JPG


For most including myself, 100 FPS gain is pretty significant. The cost of re-chambering, dies, and fire-forming brass is another story. As others noted, it boils down to personal opinion/preference. Cheers!
 

Bob Wright

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Jan 23, 2018
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Litchfield Park, Az.
I am not here to argue but this is purely relative and deserves consideration. What is considered a significant gain?

View attachment 230268

For most including myself, 100 FPS gain is pretty significant. The cost of re-chambering, dies, and fire-forming brass is another story. As others noted, it boils down to personal
I would submit, just trying RE23 in handloads, trying some primers, staying with a 140-160 cup and core class, it should increase velocity without any other barrel work. How much velocity, is the experiment. Definitely less cost.
Rechambering, yes, one step up in cost, definitely adds capacity.
But the barrel length and twist is the limiting factor for the 280AI potential, probably half the bullet designs cannot be shot well.
That's where my thoughts take me.
 

FEENIX

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Dec 20, 2008
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15,165
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Great Falls, MT
I would submit, just trying RE23 in handloads, trying some primers, staying with a 140-160 cup and core class, it should increase velocity without any other barrel work. How much velocity, is the experiment. Definitely less cost.
Rechambering, yes, one step up in cost, definitely adds capacity.
But the barrel length and twist is the limiting factor for the 280AI potential, probably half the bullet designs cannot be shot well.
That's where my thoughts take me.
I am fully aware of the twist rate, barrel length, and the limitations it presents but the gain is still significant, esp. if you load them as you are suggesting. The OP never mentioned what bullet to shoot, he simply wants to shoot further and considering an AI. If he specified a certain bullet that requires faster twist, then my response will be different. I went with the information he provided, and not speculate anything. I will never stop someone for trying an improved version. Most 280 AI owners I know ends up re-barreling to an AI (this is the opportunity to take advantage on barrel twist and length), if the case is the same for the OP, he would be set-up already.

This is why I never ask what rifle to build or buy, or what improvements to make because opinions, preferences, priorities, and funding availability varies. Cheers!
 

edward hogan

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Joined
May 7, 2003
Messages
217
Location
AK
Great thing about the AI, aside from great velocity gains with heavy bullets, is better case life due to enhanced shoulder angle of 40*. Of course, can get that, almost, with the 284win which is standard at 35*. The last Hodgdon hardback manual (#26?) shoes .30/284 and .30-06 data as interchangeable. I guess it's same for the .280rem and .284win.

Gonna rebarrel? Looking for primarily longrange performance W/Heavy Bullets? Using a standard action with a .284win variant gives you better powder performance and much more room in the magazine for loading long bullets without protruding into your case area. Bullet weight of under 150gr acceptable? The 6.5/284 is a Very Proven Performer. Much greater selection of bullet weights with a 7mm though.

One last thought is barrel longevity. The .308win and .30-06 are two great performers in this dept. The .30/284 would seem to offer all the benefits of standard 06 velocities, better case life and enhanced accuracy due to better case fill-optimum size, and the 5-7k barrel longevity. Use a long action and you got enhanced bullet seating options. What's not to like?
 

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