My new 260 AI build ...

[shepherm]

Ok, now you guys have me curious. Seems like I've got some WSF somewhere. One question, did you expand and form a false shoulder?

Mine might be a little different because I use lapua 260 brass and not 308 brass, but here is what I do. I run my 270 or 7mm expander through the neck and then I neck size with my 260 die. You don't want to size the entire neck, but adjust the die down until the bolt is stiff to close on the brass. You really cant see the false shoulder on mine but its at the base of the neck and makes the bolt stiff to close.

 

[22BRGUY]

Ok, now you guys have me curious. Seems like I've got some WSF somewhere. One question, did you expand and form a false shoulder?

No... not necessary with this cartridge

 

[Pablo]

H4831sc, I may have to change to H4350 if I run out of case capacity before getting to ~2850.

H4831sc is the powder for this cartridge, H4350 never worked in the two rifles I worked with.

 

[hillbill]

I too am thinking of building a hunting weight gun with the AI, what kind of speed gain can one expect over the standard 260 with 140s?

 

[Joe R]

Hi Guys,
I just wanted to give you a follow-up on my 260AI. Yesterday was our 600 yard match and the first time I registered as an F-Open competitor and the first time using my new rifle in competition. The rifle had 83 rounds rounds prior to the match. All of those rounds were doing fire forming of cases and some initial load development using both H4831sc and H4350. I had one pound of each to test. Somewhere along the way I realized that I did not have enough brass and powder to do fire forming, velocity and seat depth testing, and also shoot at the match. So I skipped the seating depth testing and went with my initial guess.

Yesterday was a scorcher in Houston, by 10:00 am we had temps with a heat index of 102 degrees and got up to 113 by one o'clock. Our 600 yard line has no cover so we were out in the full sun. It was a sweat fest and water drinking contest rolled into one.

Here's my score card:



During the first relay I dropped a point because some of the nearby fire ants decided to make their presence known. So I had to shake them off. My very next shot was a nine.




The other points that were dropped were my fault. I can't read mirage and wind and need some education to improve.

The bottom line is that the rifle shot beautifully, and the scary thing is that I believe there is additional precision to be squeezed out of it with good seat depth testing and more stable (fire formed) brass. I can't express just how impressed I am with this caliber and rifle.

Kindest regards,

Joe

 

[Terry Altom]

I need to get more brass formed for mine and get it out to Quantico for 600 - 1000 yards to see how it performs. I think it's going to be awesome!

 

[22BRGUY]

Holy Moly Joe...Those ants did a number on your arm for sure. Great shooting though!

 

[rardoin]

If you would have held off 6 M.O.Ant instead of 5 you would not have dropped that point. I would think that 300 fireants on my forearm would have cost me much more points than one!

Nice shooting, especially for fire forming.

 

[johnnyi]

Ouch...! Joe! But that rifle for sure showing all indications you will be shooting some high X count matched coming soon!

 

[SDDasher]

Hi Guys,
I just wanted to give you a follow-up on my 260AI. Yesterday was our 600 yard match and the first time I registered as an F-Open competitor and the first time using my new rifle in competition. The rifle had 83 rounds rounds prior to the match. All of those rounds were doing fire forming of cases and some initial load development using both H4831sc and H4350. I had one pound of each to test. Somewhere along the way I realized that I did not have enough brass and powder to do fire forming, velocity and seat depth testing, and also shoot at the match. So I skipped the seating depth testing and went with my initial guess.

Yesterday was a scorcher in Houston, by 10:00 am we had temps with a heat index of 102 degrees and got up to 113 by one o'clock. Our 600 yard line has no cover so we were out in the full sun. It was a sweat fest and water drinking contest rolled into one.

Here's my score card:

View attachment 989783

During the first relay I dropped a point because some of the nearby fire ants decided to make their presence known. So I had to shake them off. My very next shot was a nine.

View attachment 989784


The other points that were dropped were my fault. I can't read mirage and wind and need some education to improve.

The bottom line is that the rifle shot beautifully, and the scary thing is that I believe there is additional precision to be squeezed out of it with good seat depth testing and more stable (fire formed) brass. I can't express just how impressed I am with this caliber and rifle.

Kindest regards,

Joe

Which powder are you going to settle upon?

 

[mikecr]

I too am thinking of building a hunting weight gun with the AI, what kind of speed gain can one expect over the standard 260 with 140s?

One higher node.
With a 260AI and 26-28" barrel you can expect 2950-3050 near SAAMI max, which is what I see as a mid-node for better cartridges, and not a problem at all. That's a full case of either 4350 powder.
And with any cartridge this side of SAAMI max, unless you're running excess clearances at the web, your primer pockets will hold.

 

[Joe R]

Which powder are you going to settle upon?

I am committed to H4831sc, Powder Valley had it in stock and I bought 24 pounds of it.

Joe

 

[mikecr]

I don't mean offense, it's your choice.
Even with it, I believe you should reach a higher node: http://reloadersnest.com/unverified_detail.asp?CaliberID=379&ID=10679
Otherwise, you'd have been better served with a 6.5x47L.

 

[Joe R]

I don't mean offense, it's your choice.
Even with it, I believe you should reach a higher node: http://reloadersnest.com/unverified_detail.asp?CaliberID=379&ID=10679
Otherwise, you'd have been better served with a 6.5x47L.

Mike,
No offense taken. I do plan on going to the higher node its just that for some reason my barrel seems to be about 100 fps slower than expected. I didn't have time or the brass prepped and fire formed to continue working up the load and go to the match. It was one or the other.

Now that the match is behind me I am going to work up to the 2,950-3,000 range because that's were QL is telling me to go. But so far this rifle has done well at all the charges I've tried from 2,600 all the the way to 2,885. Ben had told me that this was an easy caliber to tune, but this is like no tuning. Maybe I've gotten lucky a got a hummer barrel, wouldn't that be a riot?

Joe

 

[mikecr]

It's a damn good cartridge. That's for sure. GL

 

[Joe R]

Ok Guys,
This is my final report on this thread. On Thursday (Oct 6th) I had done some more load testing at the 100 yard line but I couldn't confirm it at 300 or 600 because the range was closed. So on Saturday and Sunday (this past weekend) we had our Texas State Rifle Mid-range championships. There was a switching wind during the whole weekend that gave everyone fits, but on Sunday morning I managed to score a my first clean 600 yard match not once but twice. In conclusion, it seems to me that at mid-range this cartridge does more than hold its own. It will run with the Dashers and the 284s, and in more capable hands, it will win matches.

Kindest regards,

Joe

 

[johnnyi]

Ok Guys,
This is my final report on this thread. On Thursday (Oct 6th) I had done some more load testing at the 100 yard line but I couldn't confirm it at 300 or 600 because the range was closed. So on Saturday and Sunday (this past weekend) we had our Texas State Rifle Mid-range championships. There was a switching wind during the whole weekend that gave everyone fits, but on Sunday morning I managed to score a my first clean 600 yard match not once but twice. In conclusion, it seems to me that at mid-range this cartridge does more than hold its own. It will run with the Dashers and the 284s, and in more capable hands, it will win matches.

Kindest regards,

Joe

View attachment 991146

Awesome job Joe! I'm happy all of your hard work is paying off..! You ran some Amazing scores in very challenging conditions!

 

[Joe R]

Awesome job Joe! I'm happy all of your hard work is paying off..! You ran some Amazing scores in very challenging conditions!

Johnny,
It was the rifle and the bullet, all I did was aim it at the right line of the 10 ring and the bullet and rifle did the rest. As luck would have it in spite of the gusts the 140 hybrids seem to buck the wind very well.

 

[dewey7271]

I have 2, both 26" built for hunting.
I use Terry Cross' load from his work up. Tried quite a few others but 48.5 H4831SC was the ticket for mine. Chrono is 2940 with one, 2930 with the other. Very accurate.
You've picked a terrific cartridge.

http://www.6mmbr.com/gunweek046.html

 

[SDDasher]

Ok Guys,
This is my final report on this thread. On Thursday (Oct 6th) I had done some more load testing at the 100 yard line but I couldn't confirm it at 300 or 600 because the range was closed. So on Saturday and Sunday (this past weekend) we had our Texas State Rifle Mid-range championships. There was a switching wind during the whole weekend that gave everyone fits, but on Sunday morning I managed to score a my first clean 600 yard match not once but twice. In conclusion, it seems to me that at mid-range this cartridge does more than hold its own. It will run with the Dashers and the 284s, and in more capable hands, it will win matches.

Kindest regards,

Joe

View attachment 991146

Joe, very nice shooting. What load did you end up with?