New .260 AI

[p_ham]

I've been wanting to build one for quite a while, reamer and gauges finally showed up so it's time to get started!

This will be (tentatively) strictly a range toy so I'm not concerned with weight.

I still need to upgrade the trigger but haven't decided what I want yet.


I will post updates along the way.

 

[noharleyyet]

Nice job on the exploded image....subscribed.

 

[Deleted member 16014]

I hunted a .260ai for a few years and enjoyed the chambering a lot. Have fun with the project! What bullets are you looking at?

 

[rtraverdavis]

What kind of stock is that? Stocky’s?

 

[p_ham]

I hunted a .260ai for a few years and enjoyed the chambering a lot. Have fun with the project! What bullets are you looking at?


View attachment 163345

I'm looking at the 142SMK, 150SMK, 147ELD, 153 Berger.
I've thought about rechambering my .308 as well but I think I like it too much to do that. Guess that means I'll need another donor action?

What kind of stock is that? Stocky’s?

Yes, it's their Accublock LRC. It's not a bad looking stock but it'll need just a little bit of clean up and profiling.

 

[jryoung]

What twist are you running?

 

[p_ham]

What twist are you running?

1:8. It might be too slow for the 150+ bullets, but we will see. I'm on a long action so I have plenty of room for powder and I'm over 4000ft elevation.

 

[buffybr]

I've been an Ackley fan for a long time and have had a couple of them for over 40 years. So after reading this thread yesterday I did some checking and comparing the .260 AI and the 6.5 Creedmore.

The bullets are the same, the case dimensions are only fractions of an inch different, so I'm guessing that the case volumes are pretty close to equal. I'm a case scrounger at the range and I've picked up a lot of 6.5 CM cases but I can't remember ever finding a .260 case.

So my question is, I think having a .260 AI would be cool, but is the performance really that different from a 6.5 CM and would the extra costs of the AI chambering, AI dies, and finding and forming AI brass really worth it?

 

[JCW]

I've been an Ackley fan for a long time and have had a couple of them for over 40 years. So after reading this thread yesterday I did some checking and comparing the .260 AI and the 6.5 Creedmore.

The bullets are the same, the case dimensions are only fractions of an inch different, so I'm guessing that the case volumes are pretty close to equal. I'm a case scrounger at the range and I've picked up a lot of 6.5 CM cases but I can't remember ever finding a .260 case.

So my question is, I think having a .260 AI would be cool, but is the performance really that different from a 6.5 CM and would the extra costs of the AI chambering, AI dies, and finding and forming AI brass really worth it?

The .260 and 6.5 CM are basically ballistic equals, with the 260 A.I. I believe you can gain around 200 fps.

 

[p_ham]

I've been an Ackley fan for a long time and have had a couple of them for over 40 years. So after reading this thread yesterday I did some checking and comparing the .260 AI and the 6.5 Creedmore.

The bullets are the same, the case dimensions are only fractions of an inch different, so I'm guessing that the case volumes are pretty close to equal. I'm a case scrounger at the range and I've picked up a lot of 6.5 CM cases but I can't remember ever finding a .260 case.

So my question is, I think having a .260 AI would be cool, but is the performance really that different from a 6.5 CM and would the extra costs of the AI chambering, AI dies, and finding and forming AI brass really worth it?

The 260 AI has about 3grs (H20) more case capacity than the creedmor.
You probably won't find 260 brass on any range unless the shooter missed one when they picked up. Generally speaking if you're shooting the 260 you're a reloader.
An AI chamber costs the same as a SAAMI most of the time.
Finding brass is easy, and you can form from a number of cases in the .308win family.
Dies are a little more expensive, I'll give you that. I think I've found a way to help with that but I need to do some testing.
Fire forming is a non issue, you can load a near max charge and still be fine on a properly chambered rifle. Not to mention you can still shoot factory ammo for the SAAMI cartridge.
You also have much less case stretch which equals less trimming.

Most of all it's cool!

 

[Addicting]

Lapua or ADG brass seems to work the best. Nosler you end up with almost too short necks. I have 60 some FF if you want to try them. I switched to all ADG. N555 is a great powder for 120-130g. I pushed the 127g LRX at 3120fps out of a 24”. RL26 for the 140 class and it will run them comfortably 2925-2950FPS.

I’m having another built now with a 26” Lilja 3 groove on a REM 700 SS.

Did you buy the reamer or rent it?

 

[p_ham]

Lapua or ADG brass seems to work the best. Nosler you end up with almost too short necks. I have 60 some FF if you want to try them. I switched to all ADG. N555 is a great powder for 120-130g. I pushed the 127g LRX at 3120fps out of a 24”. RL26 for the 140 class and it will run them comfortably 2925-2950FPS.

I’m having another built now with a 26” Lilja 3 groove on a REM 700 SS.

Did you buy the reamer or rent it?

Thanks for the offer! How does the case cap. On the ADG compare to Lapua?
I was looking at N565 and RL26, I'm figuring on around 2950 for the 147ELD.
I'm going to end up at 26" on this barrel as well.
I bought the reamer from PTG it was on sale for a big discount. The throat isn't what I want but that's an easy fix.

 

[Addicting]

Thanks for the offer! How does the case cap. On the ADG compare to Lapua?
I was looking at N565 and RL26, I'm figuring on around 2950 for the 147ELD.
I'm going to end up at 26" on this barrel as well.
I bought the reamer from PTG it was on sale for a big discount. The throat isn't what I want but that's an easy fix.

Lapua has more case capacity. The ADG is thick brass but holds up better to hotter charges. N555 really shined so I never tried N565. Even with RL26’s unicorn hooves and fairy dust, getting the 147 to 2950 is going to be a challenge. Every barrel is different so keep us posted. You will get there with a 140 but it’s near max. For the heavier bullets the PRC, WSM, SAUM, or Sherman case is where it’s at in a short action.

If your interested in selling or renting the reamer, I am going to need one in December. Pierce Engineering in Lansing, MI is going to be putting my new one together.

 

[std7mag]

What is the barrel your using?

Length, contour?

Also for bullets, i'm hearing good things about the Nosler RDF.
Might want to give those a try.

Keep us posted on the build!
Looks interesting!

 

[Addicting]

Also, the Timney HIT trigger is a excellent trigger for a range gun. I have it in my 300 Sherman and love it.

 

[p_ham]

What is the barrel your using?

Length, contour?

Also for bullets, i'm hearing good things about the Nosler RDF.
Might want to give those a try.

Keep us posted on the build!
Looks interesting!

Barrel is a Wilson light varmint 1:8. Finished length will be 26".
I've been reading a lot on the RDF bullets, I'm sure they'll ge tested at some point.

Also, the Timney HIT trigger is a excellent trigger for a range gun. I have it in my 300 Sherman and love it.

I've been debating between the HIT and a Triggertech. Either way it's gotta be single stage.

 

[Addicting]

I've been debating between the HIT and a Triggertech. Either way it's gotta be single stage.

You won’t go wrong with either choice. I would try and find you a Black Friday same to pick one up.

 

[p_ham]

Got the reciever and bolt all trued up and lapped.

Also made a small diameter boring bar to save some time during chambering. O1 tool steel.

 

[p_ham]

Got the barrel threaded, chambered and headspaced.


Trimmed an inch off the muzzle end, crowned and threaded.


Made a nice thread protector, I kind of don't want to put a brake on now!


A quick mock up, stock work is next.

 

[std7mag]

I don't think you'll have to worry too much about a brake.
What did your barrel finish out, length wise? Close to you 26" goal?

Another thought for brass is Peterson. Getting pretty good reviews from the match shooting crowd.

Looks good!