260 AI help

[jd5521]

Neck sizing is stupid. There is no reason to do it.

I'm not sure what you're trying to prove here. If someone gets the results they are looking for with neck sizing that's good for them. You are correct annealing does assist with brass longevity but brass work hardens just the same in the long run. Annealing doesn't cut that out completely. As for F-class and benchrest I have never shot any match where 20 consecutive strings occur. Especially in F-class. Both these disciplines are single shot disciplines. As for Erik, great guy know him well and shoot with him. I think if he saw your posts he'd tell you settle down a bit.

 

[tylerw02]

I said twenty-round strings. Not twenty strings.

 

[jd5521]

I said twenty-round strings. Not twenty strings.

I get what you are saying but remember in matches we get up to 25 minutes to complete a string. It's not rapid succession at all. Also, with almost any improved case the case walls are blown out and taper is taken away. Unlike many other bottleneck cartridges. With these straight taper cases the brass growth is minute compared to regular bottlenecks so neck sizing these cartridges can be more effective at times than full length sizing. Improved cartridges vs other bottlenecks is not apples to apples when it comes to sizing.

 

[tylerw02]

It's not uncommon for a competition to fire many rounds in rapid succession before conditions change.

Neck-sizing still isn't going to be more effective, I whole-heartedly disagree with that notion. If there is a problem FL sizing it's probably improperly set-up.

 

[Wolf01]

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.

He is pretty sharp at keeping it simple.

 

[Mram10us]

OP,
I built a 260 improved of sorts and treat it and my 7-08 ais like anything else after the first firing. Once it is fireformed, I fl size, pushing back the shoulder just like every other cartridge. I remove the firing pin and ejector for feel. I think alex wheeler has a video about setting shoulder bump .... i could be wrong.

 

[Mikecr]

I personally could care less what F-Class shooters do or care about.
Hunting shooting is all together different.

 

[xsn10s]

All that matters is the intended purpose and desirable qualities. For a tight fitting case then neck size with the occasional bump is all you need. Trim once it's needed. For me I bump or FL resize. I like slick feeding rounds. It really all depends on your wants and needs.

 

[nkyshooter]

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!

I shoot 260 AI - it is my favorite rifle with my 6mmBR a close 2nd ... I get 2850 from the Berger 140 hunting vld's without pushing it anywhere near it's limits ... if I chose to push, I could get close to 3000 with the right powder ... more with 130's or 120's - but I want both my brass and barrel to last since they are giving me sub half moa.

Max length is 2.045 - trim to length is 2.035 but I recommend not trimming until you pass 2.045 on a few ... then, trim ALL of them to be the same 2.035 ... When you fireform it will shrink in length - possibly to less than 2.035. If it does, it isn't a problem but you might end up with a carbon ring in the chamber just past the end of the case. Just practice good cleaning and you will be ok. As you continue to load/fire, the cases will grow in length but nowhere near the rate/pace a 260 Rem case will grow. This is because the sharper shoulder resists that 'flow' of the brass.

Regarding full length sizing and/or shoulder bumping ... If your fired cases chamber too snugly, you will need to full length size to reduce case wall diameter and bump shoulder back. However, if they chamber smoothly you have the option to either full length size or neck only size. Your 'best' accuracy 'potential' comes with cases that are as close to the dimensions of your rifle chamber as possible while still chambering smoothly. This comes with 'fireformed' brass and neck sizing only until it becomes 'too' snug. I utilize a body die for this with my 6BR and would do the same if I had one for my 260 AI. As it is, I use a Lee 260 Rem neck collet sizing die until I need to full length at which time I use my Redding 260AI Full Length sizer. By the way - I spent an afternoon with Ferris Pindell (second "P" in 6mmPPC which was tops on the 100/300yd benchrest circuit for quite some time). Ferris did not full length size unless the chamber was too snug ... which never happened for him because he was running a chamber so close to unfired case dimensions and without pushing pressures. As a result, the cases did not exhibit much growth or 'snugness' ... just hand/glove fit.

If it is me and I'm headed for a hunt - I neck size then check for smooth chambering ... if good, I load ... if too snug for comfort for hunting, I full length then check for length, only trim if I must, then load. I always re-verify chambering prior to heading out for a hunt.


Enjoy your 260 Ackley - I find it to be one of the best all around blended pros/cons cartridges out there and THE best non-magnum short action 6.5 ... while it won't quite keep up with a 6.5-284, you'll get lots more rounds through your barrel before you're replacing or at least setting back ... even more so when compared to the 6.5 WSM, SAUM or PRC (although if you need super speed with a 6.5 those and the Shermans are all solid cartridges).

 

[Mikecr]

A 260AI is fully capable of keeping up with and then passing what's viable in the long term from 6.5x284. You only need to chamber for minimal clearances(as Ferris Pindell did) with plenty enough barrel steel around that chamber (magnum dia tenon, and coned breech).

I can smoke any 6.5x284 from my 26WSSM Imp build, which exactly matches 260AI capacity (by design).
The key is chamber AREA. Smaller chamber area is easier to support. So you can build with the smallest chamber providing capacity needed for chosen bullet given available powders, and support that design to SAAMI max and beyond. Then while you can go higher, plan to hold back at a mid-velocity node -putting you right near SAAMI max. If you fit the chamber to new brass, and minimally size, that brass will last beyond many barrels.

It all begins with a bullet, and 260AI capacity happens to be the best for 140gr 26cal bullets.
If you're good with QuickLoad and run every 26cal what-if in the world, all paths lead right to the 260AI.
Neither bigger nor smaller is better.
Now for 130gr bullets, that would be the 6.5x47L. It's perfect.

 

[twister]

A 260AI is fully capable of keeping up with and then passing what's viable in the long term from 6.5x284. You only need to chamber for minimal clearances(as Ferris Pindell did) with plenty enough barrel steel around that chamber (magnum dia tenon, and coned breech).

I can smoke any 6.5x284 from my 26WSSM Imp build, which exactly matches 260AI capacity (by design).
The key is chamber AREA. Smaller chamber area is easier to support. So you can build with the smallest chamber providing capacity needed for chosen bullet given available powders, and support that design to SAAMI max and beyond. Then while you can go higher, plan to hold back at a mid-velocity node -putting you right near SAAMI max. If you fit the chamber to new brass, and minimally size, that brass will last beyond many barrels.

It all begins with a bullet, and 260AI capacity happens to be the best for 140gr 26cal bullets.
If you're good with QuickLoad and run every 26cal what-if in the world, all paths lead right to the 260AI.
Neither bigger nor smaller is better.
Now for 130gr bullets, that would be the 6.5x47L. It's perfect.

what are you using for powder in your 260ai ?

 

[Mikecr]

IMR4350, full case but not packed or compressed.
My mid-load is 47.4gr, providing 3020fps/8ES at 65Kpsi, 140VLDs, 28" barrel.
I can push it to a higher node with H4350, but it's not quite as accurate, and requires FL sizing.

This is my fitted chamber in 26wssm Imp, which matches 260AI H20 capacity. It's a BAT magnum action, coned breech. If you loosely follow this path, while cutting any corner, you'll fail to reach me.
You'll pressure out early, and/or be forced to accept shorter/unstable brass life.

There are 1kyd BR shooters who have tried 260AI, and 26wssm, and they didn't do well.
But when you look closer at the whys of it, it's pretty obvious these cartridges did not fail them.
Instead, they failed the cartridges.
The sum of their planning often amounted to no more than excess -clearances/annealing/sizing/hope.

 

[twister]

IMR4350, full case but not packed or compressed.
My mid-load is 47.4gr, providing 3020fps/8ES at 65Kpsi, 140VLDs, 28" barrel.
I can push it to a higher node with H4350, but it's not quite as accurate, and requires FL sizing.

This is my fitted chamber in 26wssm Imp, which matches 260AI H20 capacity. It's a BAT magnum action, coned breech. If you loosely follow this path, while cutting any corner, you'll fail to reach me.
You'll pressure out early, and/or be forced to accept shorter/unstable brass life.

There are 1kyd BR shooters who have tried 260AI, and 26wssm, and they didn't do well.
But when you look closer at the whys of it, it's pretty obvious these cartridges did not fail them.
Instead, they failed the cartridges.
The sum of their planning often amounted to no more than excess -clearances/annealing/sizing/hope.

I am not at pressure and I'm using about the same powder charge in H4350. its built on a Sako with lilja 26" and i am throated to sit the the base at the neck junction. I will put some more rounds through it and see what happens but the groups are true 1/4" so i have little reason to mess with it other than speed.

 

[Mikecr]

In my experience, for distant hunting shooting, real accuracy trumps speed and energy.
This accuracy is not fleeting, but what you can count on as your conservative, well tested capability.

The biggest hurdle in gaining consensus with this seems to be the basic misunderstandings of accuracy -vs- precision, and hunting condition shooting -vs- competitive format.
I bark contempt for competitive influences toward hunting shooting because they're in no way related.
There is not a single correlating attribute between them.