260 AI help

cb4128

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Apr 25, 2014
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Need some tips on this caliber. I’m shooting factory berger 260 ammo with 130gr bergers to fire form my brass. After I get enough brass to work with, I’m going to work up a load.

My questions are:

- what’s the range for brass trim OAL for 260 AI?
- do I need to resize and bump the shoulder back on the formed brass? Or just trim to the same length, chamfer, debur then load? (This would be on the first loading of the formed brass)

with my other non-AI cartridges, I FL size my brass after every firing and bump the shoulder back.

Thanks for the help!
 

Mikecr

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Aug 10, 2003
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Bump only when you need to, trim only when you need to. YOUR chamber establishes this.
The necks will pull back with shoulder improvement, so if you trim before needed your chamber end clearance will be excessive. Unless you do a deep body dip anneal beforehand, you should not need to bump for at least several firings. It's important to reach this actual point so that you know that you're not bumping to excess head spacing.
 

26Reload

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Here goes again....
'IF you have a borescope' you can take a look inside and see just how much space there is between the case and the leade.....keep a watch on that area for best knowledge of when to trim and how much needs trimmed.......
Borescope is great tool for more than just looking at fire cracking and how dirty the barrel is....
 

cb4128

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Apr 25, 2014
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Ok 10/4, thanks for the info thus far. At this point I’m going to keep shooting and forming brass.

when I get to loading I’ll check and see if the brass chambers without much resistance and keep track of my trim length. Sounds like I may not need to until after the 2nd firing.
 

J E Custom

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Jul 29, 2004
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Texas
I don't recommend bumping the shoulder at all until it wont chamber and then only enough to allow it to chamber. Properly cut AI chambers are very good about holding their size and length after firing. (The reason many chose this design over standard case designs).

I would recommend prepping the 260 brass to SAMMI dimensions before it is fireformed to get a base line for the amount of growth after fireforming and then neck size only for the second firing and you will see how little it changes compared to conventional cases.

The less you work your brass, the longer it will last, and the greater the accuracy will be in my experience.

J E CUSTOM
 

tylerw02

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Feb 2, 2020
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Missourica
Forget the nonsense about not working the brass and all that. What you want is consistency!
How do you get consistency? Doing the same thing every single time. Go to an F-Class match where guys are shooting clean targets time after time. Ask them what they do. It’ll be this:

Fire-form case
Anneal
FL-size and bump the shoulder back 0.002”
Trim/chamfer/deburr in one operation
Expand necks
Prime/charge/seat

Do this every time. The annealing process alleviates any concern with “overworking the brass”.

Hunting is going to require less precision and accuracy than F-Class...when I’m hunting I want function to be perfect. Nobody wants rounds that don’t want to chamber in the middle of a hunt where your rifle is exposed to the elements.

Look up Erik Cortina and check our his YouTube channel.
 

del2les

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<snip>

Hunting is going to require less precision and accuracy than F-Class...when I’m hunting I want function to be perfect. Nobody wants rounds that don’t want to chamber in the middle of a hunt where your rifle is exposed to the elements.

<snip>

I guess that depends on what and the distance you are hunting. Much LR/ELR hunting requires the same, better or similar precision as any F class match, and as for rounds not chambering when hunting, who does not chamber check their rounds prior to their hunting trips? YMMV
 

tylerw02

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I don’t know any hunting situation where one would shoot 20 round strings needing to be sub-half MOA.

Neck-only sizing is silly and offers no advantage other than being easy for those that suck at setting up FL dies. If there was any advantage, you’d see it in F-class and BR. But you don’t, it’s exclusively FL sizing.
I guess that depends on what and the distance you are hunting. Much LR/ELR hunting requires the same, better or similar precision as any F class match, and as for rounds not chambering when hunting, who does not chamber check their rounds prior to their hunting trips? YMMV
 

tylerw02

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Feb 2, 2020
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I don’t know any hunting situation where one would shoot 20 round strings needing to be sub-half MOA.

Neck-only sizing is silly and offers no advantage other than being easy for those that suck at setting up FL dies. If there was any advantage, you’d see it in F-class and BR. But you don’t, it’s exclusively FL sizing.
And at 1000 no less.
 

Txrockman

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Aug 6, 2013
Messages
25
No experience with the 260AI but have a 280AI fire formed from 280 Remington and shot about 100 rounds that way and now on 4th reload on that brass. I check for proper length trim if needed and neck size only. Seems to be working fine but I do not load hot loads. No need to eat up all my parts ie. barrel and brass. Hope that helps.
 

Gibbshooter43

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Feb 2, 2016
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Cottonwood Creek @ Myrtle, Idaho
I'm with Jerry on this one. Shooting 3 AI’ed cartridges and 2 Gibbs rounds, I have yet to have a round not chamber. That for me is one of the advantages of the AI cartridges, with increased velocity being secondary.
 

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