Winchester Model 70 .280 Remington upgrade to AI

[john k]

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.

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.

Thanks. I was fortunate to trade a friend some IMR 7828sc for RE23. The only primers in my possession are Rem 9 1/2, CCI, and CCI magnum. Thanks again

 

[TC0802]

If you're not already set up to reload the 280 Rem I'd say jump on a rebarrel job. Will the difference be THAT much? Probably not, but those minute advantages are what we are all about right?
I have a 280 Rem that I have really loved. The only reason I haven't went to the AI is cuz I'm already so invested into the reloading aspect of the 280 Rem.
I will say I have murdered elk with the 280 Rem. Shouldn't have any worries there. I've had great success w/ the 154 Interbonds using IMR 4831.
Good luck.

 

[Bob Wright]

I was "fortunate" to have a worn out 7RM, and switched it to a 280AI just on what I studied here. It went to a 26" with a brake and without pushing too hard with Nosler brass, I'm getting 3100 fps. Leaving a lot on the table with Nosler brass. It's a tough call for the OP, I'm sure. Peterson brass is loaded now to see if i can grab that next node at 3200.
Just try that next powder and primer and see if you can squeeze some velocity. Then go for a chamber job if you want. The AI will show you where your twist limits will decide bullet configuration.

 

[Blunder98199]

This June I did exactly what you're contemplating on my brand new M70 Supergrade and am thrilled with the results. Even with the standard 1-10" twist in the M70 280 barrel, my fancy 280 AI shoots 162 ELD-X over 60 grains of Reloder 23 into tidy little sub-.5 MOA groups...SUPER fun!

You might know there are two approaches to "Ackley-izing" a .280: the old way that PO Ackley prescribed, and the new way approved by SAAMI..there's a slight but meaningful difference (.014") in headspace. It makes most sense to go the SAAMI route. Alas, I had no idea about the two approaches so asked a rather famous but old school gunsmith to do the work, and he did it as he'd done for the previous 50 years. The problem is I cant use factory Nosler ammo and must reload. I started that in June, too! So, it's cost me some additional cash, but I'm learning a great deal and having a blast with the new hobby and gun.

Bottom line: do it...it's fun, it'll keep your brain churning on rifle silliness, and you'll find yourself at the range more often. is it necessary? Nope...but it's fun.

 

[JohnT]

This June I did exactly what you're contemplating on my brand new M70 Supergrade and am thrilled with the results. Even with the standard 1-10" twist in the M70 280 barrel, my fancy 280 AI it shoots 162 ELD-X over 60 grains of Reloder 23 into tidy little sub-.5 MOA groups...SUPER fun!

You might know there are two approaches to "Ackley-izing" a .280: the old way that PO Ackley prescribed, and the new way approved by SAAMI..there's a slight but meaningful difference (.014") in headspace. It makes most sense to go the SAAMI route. Alas, I had not idea about the two approaches so asked a rather famous but old school gunsmith to do the work, and he did it as he'd done for the previous 50 years. The problem is I cant use factory Nosler ammo and must reload. I started that in June, too! So, it's cost me some additional cash, but I'm learning a great deal and having a blast with the new hobby and gun.

Bottom line: do it...it's fun, it'll keep your brain churning on rifle silliness, and you'll find yourself at the range more often. is it necessary? Nope...but it's fun.

Blunder can you please share what velocities you are getting with the 162gr ELD-X? My M70 SG us still stock std 280Rem and it's a shooter too but have not played with the heavy weight bullets yet. Sent to gunsmith to have trigger lightened. I don't know why the MOA is advertised as adjustable when it is not. Needs new springs!

 

[Blunder98199]

Blunder can you please share what velocities you are getting with the 162gr ELD-X? My M70 SG us still stock std 280Rem and it's a shooter too but have not played with the heavy weight bullets yet. Sent to gunsmith to have trigger lightened. I don't know why the MOA is advertised as adjustable when it is not. Needs new springs!

Hi, JohnT - After lots of work, I'm at 3000+/- FPS...it took a while until I realized that I needed to trust the 40 degree shoulder to handle bigger pressures, eg 62k...I'm using Peterson brass (expensive but STOUT!) so feel comfortable putting some juice behind the lead.
On the trigger, I was able to lighten mine up a fair bit...is your SG a recent vintage? Mine is a 2019/2020.

 

[JohnT]

Hi, JohnT - After lots of work, I'm at 3000+/- FPS...it took a while until I realized that I needed to trust the 40 degree shoulder to handle bigger pressures, eg 62k...I'm using Peterson brass (expensive but STOUT!) so feel comfortable putting some juice behind the lead.
On the trigger, I was able to lighten mine up a fair bit...is your SG a recent vintage? Mine is a 2019/2020.

Thanks Blunder. Wow that's 7mm Rem velocities. My SG is the made in Portugal one but dont know the year of manufacture. Have another M70 SG in 30-06 made in USA by FN. Trigger was very crisp but heavy so I sent it to my gunsmith to replace the springs. I have backed the trigger screw right out pn the FN USA made one with no change in trigger pull weight so didnt even bother to try to adjust this one. Just sent it off.

Still it's pretty awesome what you get for the money in terms of a classic hunting rifle!

 

[Blunder98199]

I just got a 280Rem in a M70 SG made in Portugal. Can confirm it is indeed a 1:10 twist. My initial thoughts were exactly that. Rechamber to 280 AI but with that twist rate it's a rebarrel job!

I have the same gun and did the AI upgrade...I am shooting 162 ELD-X beautifully, and will be shooting 175 Woodleighs soon...no stability problems with that bullet according to the JBM calculator.

 

[mmacfive]

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

Why would you loose a round down going to the AI?

 

[mmacfive]

The AI gives you about a 4 gr case capacity increase. If one is hand loading the 280 & 280AI to the same pressures (let's say 65kpsi) the AI will have about a 1% velocity increase, or less than 50 fps.

I've never had a problem running 160's between 2950 fps and 3000fps in a standard 280 with brass life near 10 firings.

someone on here said that the additional 100 fps is worth it. I don't think you'll get 100 fps and if you do that means less than a 75 yard gain.

I'm having Melvin Forbes screw on a new barrel as we speak. In a standard 280. But then I also own a 7 STW.....

 

[JohnT]

I have the same gun and did the AI upgrade...I am shooting 162 ELD-X beautifully, and will be shooting 175 Woodleighs soon...no stability problems with that bullet according to the JBM calculator.

Woodleighs are a great Aussie bullet Blunder. They don't just test on gel they actually test it on game. I used the 300gr 375 Protected Point in Africa last year and performance was superb including 1 shot kill on Cape Buffalo. Accuracy in my 375 was also excellent.

That said they are not a high BC bullet but for hunting they are superb. For that reason the 175's should stabilise fine. I have some 160 PP to try in mine.

As you said it's all fun whether you AI or not. Here in Oz we don't have as many good gunsmiths (especially for M70) and the wait times are long. For that reason most likely I'll keep mine as a std 280Rem.

I'm enjoying the noticeable recoil reduction from my 30-06.

 

[jbo829]

Why would you loose a round down going to the AI?

Shoulder angle