Will a 260AI clean up a 6.5 CM chamber?

[Wilderness Blacktail]

In my .260 AI with a 29" barrel, I am shooting the 156 EOL at 2940 fps using RL26. Pressure signs didn't appear until I was right at 3000 fps. In speaking with another member shooting them out of a 20" .260 AI, he was attaining 2725 fps

Cody, did you happen to run 147s out of it? Jus curious, I have run those and get 2880' but have not tried the 156.

 

[codyadams]

Cody, did you happen to run 147s out of it? Jus curious, I have run those and get 2880' but have not tried the 156.

Yup. For them, the most accurate load was pretty close to max, it was only about 20 fps shy of pressure signs, and was 3040 that I used as a hunting load for a season. Running at comparable pressure to the 156, the 147 is only about 50-70 fps faster, in my experience in my .260 AI and a .264 wm. Keep in mind, this is out of my 29" barrel using rl26. With H4831sc for instance, the 140 VLD's maxed out around 3000 fps, the same speed as the 156 using rl26. That load (140 vld, H4831sc) shot stupidly accurate at 2930 fps.

 

[Wilderness Blacktail]

Gotcha. Good info man, thanks.

 

[LongBomber]

JE would be right. Don't have reamers to measure at home, but going by fired brass the 260AI is 0.0015" from cleaning up a cm chamber. Took measurements from three fired cases of each, its close but it won't clean it up without setting back at least two threads.

Really you are better off chambering up a new barrel anyways, but sometime you need things done on the cheap. It is close, but not quite.

Please measure LongBomber.
I'm having a hard time finding a 260AI reamer print or drawing because it's not a SAAMI cartridge.
The only drawing I can find shows the 260AI shoulder measuring 0.459"
The 6.5cm shoulder is wider at 0.462" (I have a drawing for this).

If this is the case, a 260AI reamer would not fully cleanup a 6.5cm chamber.
Here, it would not really be Ackley Improved, and dies would not work right at the shoulder.

Personally, I would just get a new barrel blank, and order a 260AI reamer set for it's chambering.
It is IMO, the best in 26cal.

 

[Wilderness Blacktail]

Yep, I've scrapped the idea of a rechamber and just putting thot into perhaps building a 260AI later if I wear this barrel out.

 

[Hawkeye Pierce]

You could check with Defense Edge on their 260 terminator with +p throat runs 140s over 3000 with RL-26. I believe it is a custom blown shoulder and it's worth the phone call.

 

[338 dude]

Please measure LongBomber.
I'm having a hard time finding a 260AI reamer print or drawing because it's not a SAAMI cartridge.
The only drawing I can find shows the 260AI shoulder measuring 0.459"
The 6.5cm shoulder is wider at 0.462" (I have a drawing for this).

If this is the case, a 260AI reamer would not fully cleanup a 6.5cm chamber.
Here, it would not really be Ackley Improved, and dies would not work right at the shoulder.

Personally, I would just get a new barrel blank, and order a 260AI reamer set for it's chambering.
It is IMO, the best in 26cal.