280 Ackley ballistic questions

[Mike D Texas]

As if I need to add another cartridge to my safe, I had a chance to visit the Weatherby factory when I was in Wyoming. While there I held a MkV backcountry 2.0 Ti rifle and I was blown away at how light weight it was (Under 5#).

The only cartridge offering that piqued my interest was 280AI. I've been considering an ultra light pack rifle for some time and this one really keeps sticking in my head.

it comes with a 24" barrel but was wondering how much velocity loss I would see by cutting it to 20" and retreading for a suppressor. Quick load predicts 3000 fps with 150 class bullets using RL26. While I would prefer to use a Hodgdon extreme powder, they leave a lot of velocity on the table with H4350.

So the question is, does anyone shoot a 280AI with a short barrel and have any real world velocity data they can share?

 

[SnakeRiverEric]

I have the kimber mtn ascent in 280AI with 24" barrel. I get 3170fps with the 143gr Mcguire ballistics(MB) bullet, 3080fps with the 160gr MB, 2950fps 160 Accubond. Using 58-59gr RL23.
I too have looked at the BackCountry 2.0 in 280AI as well, waiting for the Kimber barrel to go south.

 

[Mike D Texas]

I have the kimber mtn ascent in 280AI with 24" barrel. I get 3170fps with the 143gr Mcguire ballistics(MB) bullet, 3080fps with the 160gr MB, 2950fps 160 Accubond. Using 58-59gr RL23.
I too have looked at the BackCountry 2.0 in 280AI as well, waiting for the Kimber barrel to go south.

Yeah I was hoping to hear from someone shooting a 20" barrel.

 

[BEEMAN]

My 280 AI has a 23" barrel. 140 absolute hammers at 3300 FPS plus. This is with H100V. The AH line might be worth looking at depending how far you plan to shoot.

 

[Mike D Texas]

My 280 AI has a 23" barrel. 140 absolute hammers at 3300 FPS plus. This is with H100V. The AH line might be worth looking at depending how far you plan to shoot.

I won't be shooting Hammers. Your velocity is impressive.

 

[iiiNelson]

My 280AI has a 24" barrel. That being said, if I remember correctly there was a greater drop off per inch once you go below 22" (if I remember correctly) from a test that I read that compared speeds going below a 26" barrel. There was about 20-30fps per inch down to 22" but going below that it moved to like 25-40fps in that test. In either case the velocity was comparable to a 18" 7 SAUM with a 20" 280 AI.

So I'm guessing you'd lose around 120-150fps give or take for cutting off 4" from your barrel.

 

[BigGriz]

Here is my load and some chronoed factory ammo.

Savage Ultralite - factory 22" proof barrel

160 gr accubond
Nosler brass - BR2 primer
61.2 gr H4831
2810 fps very consistent


Factory loads
Hornady precision hunter 162 eld-x
2813 fps avg

Nosler trophy grade 160 accubond
2830 fps avg - velocity inconsistent

Federal premium 155 terminal ascent
2890 fps avg - velocity consistent

Federal premium 168 Berger hybrid
2730 fps avg

 

[adk hunter]

My friend is a Weatherby fan. I steered him to the .280AI. He was drooling over the 6.5 weatherby. He saw one and bought it.

We were going to do some load development here. He had shot it a few times. Went to rack first round in and wouldn't close. Maybe the round wasn't to spec. Next one was hard but chambered and shot. Rough extraction! He said it just needs breaking in. Try another. Nope!! I said it is already broken! He sent it back and they did something. Came back good to go. Turn around time was excellent but stressful right before his hunt.

It carries like a dream! He killed his moose and guide said it was one of the fastest deaths he's seen. (Newfoundland) His son shot dandy wt. a few weeks later.

I don't think you can cut and thread it back as far as 20'' with the fluted barrel. Perhaps something to check?
Hope this helps.

 

[Veteran]

As if I need to add another cartridge to my safe, I had a chance to visit the Weatherby factory when I was in Wyoming. While there I held a MkV backcountry 2.0 Ti rifle and I was blown away at how light weight it was (Under 5#).

The only cartridge offering that piqued my interest was 280AI. I've been considering an ultra light pack rifle for some time and this one really keeps sticking in my head.

it comes with a 24" barrel but was wondering how much velocity loss I would see by cutting it to 20" and retreading for a suppressor. Quick load predicts 3000 fps with 150 class bullets using RL26. While I would prefer to use a Hodgdon extreme powder, they leave a lot of velocity on the table with H4350.

So the question is, does anyone shoot a 280AI with a short barrel and have any real world velocity data they can share?

Mike, what does QL predict w 20 inch bbl for the load you want to shoot? Curious how that looks vs. feedback you got here on real world
for 22 to 23 inch bbls?

 

[Mike D Texas]

Here is my load and some chronoed factory ammo.

Savage Ultralite - factory 22" proof barrel

160 gr accubond
Nosler brass - BR2 primer
61.2 gr H4831
2810 fps very consistent


Factory loads
Hornady precision hunter 162 eld-x
2813 fps avg

Nosler trophy grade 160 accubond
2830 fps avg - velocity inconsistent

Federal premium 155 terminal ascent
2890 fps avg - velocity consistent

Federal premium 168 Berger hybrid
2730 fps avg

Thank you. I forgot about the 155 Terminal Ascent bullet. That would be my first choice if I go this route.

 

[Mike D Texas]

My friend is a Weatherby fan. I steered him to the .280AI. He was drooling over the 6.5 weatherby. He saw one and bought it.

We were going to do some load development here. He had shot it a few times. Went to rack first round in and wouldn't close. Maybe the round wasn't to spec. Next one was hard but chambered and shot. Rough extraction! He said it just needs breaking in. Try another. Nope!! I said it is already broken! He sent it back and they did something. Came back good to go. Turn around time was excellent but stressful right before his hunt.

It carries like a dream! He killed his moose and guide said it was one of the fastest deaths he's seen. (Newfoundland) His son shot dandy wt. a few weeks later.

I don't think you can cut and thread it back as far as 20'' with the fluted barrel. Perhaps something to check?
Hope this helps.

Good point on the fluting.

 

[Mike D Texas]

Mike, what does QL predict w 20 inch bbl for the load you want to shoot? Curious how that looks vs. feedback you got here on real world
for 22 to 23 inch bbls?

Tim, QL predicts 3017fps with a 150ABLR and RL26 powder (I have plenty of this). That's at straight SAAMI length and no adjustments with a 20" barrel. H4350 predicts high 2800/low 2900 range if I recall.

 

[BEEMAN]

Thank you. I forgot about the 155 Terminal Ascent bullet. That would be my first choice if I go this route.

Sure wish I could find some of the terminal ascent try. I'll do more looking this winter. I've never seen them in Canada. I've only looked for the bullets not factory ammo.

 

[Mike D Texas]

Sure wish I could find some of the terminal ascent try. I'll do more looking this winter. I've never seen them in Canada. I've only looked for the bullets not factory ammo.

Yeah they are almost impossible to find as components. I've gotten lucky and found some on Gunbroker, but paid a premium for them.