260AI for Fclass 300/500/600y mainly

[countyboy]

Hi Guys

I know that 7mm rules for 1000 these days it seems but I am a 6.5 guy. I have experience with 6.5x47 and 260. I am thinking of buying an unfired 260AI that a friend built by the smith who has build stuff for our group. He is more into other stuff these days.

My questions are:

1)Aside from Terry's article on 6mmbr, http://www.6mmbr.com/gunweek046.html and Mysticplayer's (see below) are there any good sources of info for 260AI
2)For fireforming can I use a 260 load like 40-42 gr H4350 for forming? Any data on H4350 for 260AI (I know Terry liked H4831SC but I have more 4350 than 4831 at the moment)

I have read about problems forming 260 AI on 6mmbr but that seems to be more with using 243 brass necked up creating a donut I believe. I would have Lapua 260 brass.

I have heard that Terry from the 6mmbr article is not using 260AI anymore and went to straight 260. I have read about people getting 12 reloads without much trimming on the 260AI vs the 260/308 case design which is like pinnochio being a politician. I find 6.5x47 is good for trim length.

I get about 2830 fps for 140's with my 6.5x47 is another 100+ fps worth it?

I don't mind the fireforming using 260 loads but I don't like the cream of wheat idea that much sounds messy (Edit: we do have lots of space but it was meant as a humorous statement. Apologies.)

Mysticplayer, any thoughts you could share would be most helpful too as I know you did alot with the 6.5 mystic a few years ago. I just reread your 6mmbr article last night too (http://www.6mmbr.com/gunweek075.html)

Thanks Guys

 

[elkhuntr]

You could like the AI just for the fun of wildcatting. Another question is whether you want to run the max on a smaller capacity round or run a bit milder with a larger capacity round. Same result, just more wear and tear for your consideration when running hot. I like the AI for the stable brass option alone. Expect around 8-1000 rounds before your barrel starts to show signs of its demize (maybe 1200 where you are lighter on the loads.)

Found great results with 130gr bergers and H4350. Fire form with a near max 260rem load (actually, do your load testing with the fire forming to find some nodes and you are not wasting barrel life). The AI shoulder provides very stable brass and is a real bonus. Neck down brass where possible. You will want to explore the false shoulder method to ensure positive ignition and minimal brass flow if your necked down brass does not feel some resistance when chambering. I ran 140s in the 2850 range out of a 28" barrel with ease and you can hod rod it up to 2925 or so, but I found the milder node the be very consistent. 130 bergers running 2950 or better is another great consideration.

My 2c.

 

[Mystic Precision]

If you are running the 260 AI, form using Cream of wheat method AT THE RANGE. You cannot fire a rifle at home unless you are on some large farm with agreeable neighbours.

Case life is fantastic and will last several barrels when pressures are kept sane. Easy to push a 140gr VLD to 2850fps - amazingly stable node. If you go faster, I would use a larger case. You can get more speed but tuning becomes a pain.

Use 260Rem dies. I necked down 308 Winchester brass and it was a superb combo. DO NOT NECK UP 243 brass unless you want to deal with a litany of headaches.

H4831SC, CCI BR2. Throat for 2.95" OAL with a 140gr VLD and seat just off the lands (little to no engraving). Load up and enjoy...

Jerry

 

[ivo]

I am getting 3012 fps on average using RL 17 and 140gr Bergers with no pressure signs whatsoever out of a 29" barrel. I am also using un-preped Lapua .243 brass with no issues. I am not a competitive shooter nor is this a competition rifle but it is scary accurate for my purposes. I regularly shoot inside an inch at 300m with the odd 1/2" five shot group.

I love everything about this calibre except of course the barrel life.
One could opt for the straight .260 Rem and 130gr bullets and probably get similar performance I would think.

I would also agree with the notion of developing loads while fireforming.

 

[jugi16]

You answered your own question. Terry isn't using the 260AI any more. It's not worth the added effort for 75 FPS.

I'm easily getting 2850 with a 26in barrel using 140's over H4350. Just shoot the 260 with Lapua brass....

 

[countyboy]

Thanks guys. I am not sure if I am really gaining that much as I am getting 2800+ FPS with a 140 and 2900+ with 130's with both my 6.5x47L and 260. Case life and design are intriguing.

I guess barrel life is in the eye of the beholder (in terms of acceptable accuracy). I have read some people get 3000 rounds to a barrel but that sounds more like the tactical precision crowd where MOA sounds ok. I have 1000 through my
6.5x47L and it is still working great. Not sure I like the idea of a barrel going south at 1000 to 1200. I am hoping to get 2000 out of my 6.5x47 and thought I might get similar if I didn't hot rod the 260AI too much. If I am going for closer to 6.5x284 speeds I would imagine barrel life would be similar to 6.5x284

I would do some load development during fire forming rather than what COW. We do have lots of space here but I do all my shooting at a proper range. Sorry, for what in hindsight was not a smart attempt at humor.

I am not really clear on the false shoulder thing I will have to do some further investigation.

Jugi, if it weren't for my friend having a 260AI, I doubt I would go down that path. But I thought I would ask opinions. I do find CGN to be one of the best sources of info.

 

[Crashman]

I have a 260 improved with a 35 degree shoulder. So far all I have shot out of it is fireforming loads with straight up 260 brass from Lapua, accuracy was good...between 0.5 to 0.8 MOA consistently. Now I have 100 pcs of fire formed brass, have loaded up several loads to try and will get to the range as soon as I can to let some fly. Likely next week at this point as work is sticking it's nose in where it doesn't belong!

I have had regular 260 in the past and really liked them, I went with this because I could ie: it was available to me at the time. Is it better? Is it worth the effort? I will know soon enough I guess.

 

[ivo]

I do find CGN to be one of the best sources of info.

Be very selective about the info you get from this website. While there are many great resources on this website with a wealth of knowledge to share they are becoming far and few between these days, probably because of some of the........ well, just be selective about your sources of info.