Building a 280AI

[nhenry]

A 1:9 will stabilize all but the heaviest of 7mm bullets, or the middle weight mono bullets.

Heck even my 1:10 twist 7mm Weatherby stabilizes the 175gr ABLR.

If the Terminal Ascent is a mono, at 155gr, it will need a faster twist.

For the OP's stated 160-170gr bullets, the 1:9 will be fine.

The terminal ascent is just an upgraded trophy bonded tipped. Shank made of copper, nosecone is a bonded core.

 

[brymoore]

I don’t own one, might rebarrel one of my number ones into one, but I think the 280Ai is the most under appreciated cartridges out there.

Absolutely. I love how it performs and kills elk.

 

[bobcat_trapper]

Hornady says ELD X 175gr [email protected].
And the ELD M 1@8. I got a 1@8 twist. To play around with the 175 and 180 gr.
Fixing to start a load development .

 

[Wind Gypsy]

9 twist should be fine for 160-170 lead core bullets. I like 8.5 mo better for some flexibility to shoot heavies and slicker monos.

 

[std7mag]

The terminal ascent is just an upgraded trophy bonded tipped. Shank made of copper, nosecone is a bonded core.

So I looked up the Terminal Ascent bullet.
It looks like it is about 50% copper.
Hence it would be longer than the typical cup & core bullet of the same weight.
Possibly running into stability issues.

 

[p_ham]

Do you have any photos? The heavy sporter is only 8 oz heavier than the sporter. I am curious how that pencils out on his rifle.

Heavy sporter Barrel: 3.5 pounds
Boyd’s Stock: 3 pounds
Action: 1 pound (approximate guess)
Scope+rings: 1 pound

Total: 8.5

Your complete action will be about 2.5lbs.
Add another 4-6oz for your scope rings/ bases unless you've got a super lightweight scope.

 

[jwatts]

I rebarreled a 700 Mountain Rifle in 280 to a 280AI a few years back. I've had the gun since 1995 and had absolutely shot the barrel out. The throat was so eroded I couldn't get anything to shoot accurately from it anymore. I went with a PacNor #2 contour (similar to the Remington Magnum Sporter) in a 1:8 twist. It shoots pretty much anything up to a 175 ABLR. I haven't tried anything heavier or longer, but it's a laser with a 162gr ELD-X, a 175 ABLR, and even 140 Core Lokts in 280 for fire forming. I stuck with the 162 ELD-X loaded over 4831SC since it seemed to be more temp stable and have lower spreads in velocity despite temperature swings.

 

[BAKPAKR]

What do you plan to use this rifle for? If it is going to be primarily a range/stand gun you might build it one way, but if it is a woods gun with an occasional longer shot possible, you might build it another way. I had mine put together for lugging around through the woods, primarily in my hand. It weighs a little under 7.5 pounds as it sits in the photo.

 

[Arcola]

And it ain't a Creed or PRC. The 6.5-06 always creeps into my mind also. Takes two cartridges to sway away from a RUM. mtmuley

280ai & 300nmi?? I’m a sucker for increased shoulder angles.

 

[std7mag]

Hornady says ELD X 175gr [email protected].
And the ELD M 1@8. I got a 1@8 twist. To play around with the 175 and 180 gr.
Fixing to start a load development .

When talking with a Hornady tech on their help line, he told me that a "1:10 absolutely will not stabilize their 105gr Match bullet in a 243 Win".
I'll be polite and say that he was mistaken.
Shooting them proved them to be very accurate.

 

[std7mag]

@wtrfwlhunter,

I'm thinking about doing one on either the Savage 111, or Savage Axis II action.

I used a 111 action to build my 257 Roberts AI.
I'm using the factory 111 stock on it with the hinged floor plate.

Myself and a friend of mine have used Boyds Stocks on several builds. Not the lightest. But price is affordable, and they shoot and carry well.

Choate make 2 stocks for the Savage that are affordable.
Heavy as all get out at 4lbs. Ok for building a budget benchrest rifle, too much weight for my liking for a hunting rifle. Put my wife's 110 FP right at 14lbs.

I've been wanting to try the GRS stocks. These seem really interesting to me.
But I'd like to actually handle one before I shell out $500.
Mostly wondering how the grip fits.

MDT makes chassis system for the Savage. Sometimes you can run across a used one for fairly cheap.

Best of luck & keep us updated.

 

[wtrfwlhunter]

I ended up going with a bell and Carlson stock and Criterion 1:9 twist sporter contour barrel. It’s at the gunsmith now getting the action bedded.

Loaded up some 162 ELD-X with 55gr 4831sc to break in the barrel with. Anybody have any load suggestions?

 

[Jbotto]

I ended up going with a bell and Carlson stock and Criterion 1:9 twist sporter contour barrel. It’s at the gunsmith now getting the action bedded.

Loaded up some 162 ELD-X with 55gr 4831sc to break in the barrel with. Anybody have any load suggestions?

I think you’ll be very happy with that barrel. What length did you end up with?

 

[BAKPAKR]

You saved yourself some significant weight over your original plan with the new barrel contour and stock choices. I look forward to hearing how the finished rifle shoots.

 

[wtrfwlhunter]

I think you’ll be very happy with that barrel. What length did you end up with?

Thanks. It is a 24 inch barrel.

 

[jwatts]

I ended up going with a bell and Carlson stock and Criterion 1:9 twist sporter contour barrel. It’s at the gunsmith now getting the action bedded.

Loaded up some 162 ELD-X with 55gr 4831sc to break in the barrel with. Anybody have any load suggestions?

I won't have my load book in front of me for a little over a week, so I don't know the exact charge. I found a good node with 162 ELD-X and 4831SC around 2880fps out of an 8 twist PacNor barrel.

 

[nhenry]

I ended up going with a bell and Carlson stock and Criterion 1:9 twist sporter contour barrel. It’s at the gunsmith now getting the action bedded.

Loaded up some 162 ELD-X with 55gr 4831sc to break in the barrel with. Anybody have any load suggestions?

59.3 is max with H4831 in Hornady’s manual. 59 is what Nosler’s book says for 160gr bullets.
Here’s the page of Hornady’s book:

 

[Forkyfinder]

59.3 is max with H4831 in Hornady’s manual. 59 is what Nosler’s book says for 160gr bullets.
Here’s the page of Hornady’s book:
View attachment 336906

Gotta say 280AI is pretty dang efficient. Thats basically even with 7mm rm ammo/data and only 100ish fps short of 7mm prc.