Accuracy International AW in 260 Rem (PICS)

Status
Not open for further replies.
Zak Smith

Zak Smith

Member
Joined
Dec 24, 2002
Messages
9,174
Location
Fort Collins, CO, USA.
A while back I got a great deal on a used AI-AWP. Since I already have a 308, I decided to get a .260 Remington barrel for it. The logic is that for long-range shooting, wind drift is the crux of making first-round hits. While 308 match bullets (150-175gr) generally have a BC of 0.53 or less, the 6.5mm bullet have BCs are high as 0.64 for the 140-grain bullets. With similar muzzle velocity, higher BC translates directly into less wind drift. The .260 Remington can shoot the high-BC 139-142gr bullets at 2800-2900fps from a 26" barrel .

George Gardner (GA Precision) chambered and fitted this 26-inch medium-Palma from Rock Creek to the AW action. Due to the AW receiver design, headspaced barrels can be swapped at-will in about 5 minutes.

The result feeds from the double-stack AI DBM, runs perfectly in the short action, and has a trajectory significantly better than 308. At 1000 yards, a moderate 260 load shooting the 139gr Lapua Scenars has 25% less wind drift than the best 308 loads, and only 10% more than good 7 Rem Mag loads.

After spending a few hours developing loads at 100 yards, the first two shots out of the rifle past 100 were both first-rounds hits centered on two different 690-yard targets. 260's recoil with the 139's is less than 155-grain 308 loads. My current load shoots the 139gr Scenars at 2840fps, and I think 2900 fps may be safe with the right load.

Scope is a S&B 3-12x50mm PMII.
B100_1250_img.jpg [ link to LARGER image ]

B100_1239_img.jpg [ link to LARGER image ]

My 308 JET suppressor is actually quieter on the 260 than it is on my 308.
B100_1237_img.jpg [ link to LARGER image ]

Crummy through-scope picture of sets of targets at 650 (right) and 690 yards (left). The small targets are about 10" across, while the large ones are 12x18". Reticle is the S&B "Fine P4".
B100_1199_imgc.jpg [ link to LARGER image ]


The pictures were taken at June's Sporting Rifle Match at the NRAWC in Raton NM.
 
Very nice.

Man, that 34mm main tube on the S&B looks huge.
 
Sweet!

Any consideration of .260 Ackley Improved? (You reload already, no desire to fireform?)

One day, we're gonna see Zak with a 6.5 x 284.
 
Congrats, Zak!

Welcome to the world of 6.5mm! :D

RugerOldArmy, I agree, we will indeed see Zak with a 6.5x284 one of these days. ;)
 
Zak and Gixerman1000 are the guys I email when I want the answer to "what do I get for the guy who has everything?" :p

jmm
 
Chris,

re: the Horus. You actually CAN get a Horus installed in some PMII scopes. I got the 3-12 because I wanted something that was a lot smaller and lighter than the SN3. The finer reticle helps for getting a sight picture on small target or when there is very low target contrast (ie, a steel plate with a bunch of hits on it already)... however, the Fine P4 lacks the regular windage marks which I prefer for hold-off. I don't know which of this scope and the Horus/SN3 will end up on the 260 vs the 308, but in the interest of not thrashing everything right before a big match, the PMII is on the 260 for now.

RugerOldArmy,

I strongly considered the 260 Ackley. For the volume I shoot, I didn't want to have to firstly fireform everything and spend even more time on brass prep. A couple friends are building rifles in that caliber. I deicded that for now, I'll shoot the 260, then wait and see their results. If they get noticably better results with the Ackley, I'll ream out the chamber in this barrel when it's toast and use it to fireform, saving the next "real" 260AI barrel for real shooting. I had also considered 284 and 6.5-284, but the 284 case will not run in the AW mags.

-z
 
Here's what I wrote about 260 in the other thread--
The .260 Remington seems to be not enjoing much success as a mainstream rifle cartridge. It's even more rare than 7mm-08. Both cartridges have been around for a long time as wildcats of the 308 case.

For target and practical long-range shooting, the 260 makes a lot of sense. It is more overbore than 308, which means we can shoot those long and skinny high-BC bullets at high velocity, yet it is not as overbore as the 6.5-284 and 264 Magnum so barrel life is much better. The other benefit of the 260 is that any 308 caliber rifle can be converted with just a barrel change. Magazines and bolt face are identical.

As far as ballistics, the 260 can sling a 139-142gr bullet at 2800-2850fps from a 26" barrel, or a 120-123gr bullet at 2950-3100fps. Typical BC's for the 140-gr-class bullets are 0.58 - 0.64, and typical BC's for the 120-123's are 0.51 - 0.55. The best 308 can do is a 0.508 @ 2850-2900, or a 0.64 (200+gr) at maybe 2400-2500fps.

This translates into 12 - 20 inches less wind drift (10mph cross) at 1000 yards, and a flatter trajectory with the 139-140-gr bullets. With the 123's, the 260 is flatter still - approaching 338 Lapua (250's) - and the wind drift is still 10-15" better than the best 308 loads at 1000. At 1000 yards, the 139gr 6.5mm bullets have within 5% of 308's momentum, so knocking over distant steel is not a problem. 260 has noticably less recoil.

The downsides to 260 are that there is currently no good factory "match" ammunition available here in the U.S., there is no Lapua-quality brass available in 260, and it is a bit more finicky to reload than the 308. I have heard rumors that Black Hills may produce 260 soon. I have also heard rumors that in Europe, Lapua has 260 ammunition.

Reloaders have basically two choices for brass: 1. use Remington (R-P) .260 brass, 2. use some other brass and neck it up/down.

The batch of 1000+ R-P that I have played with has relatively loose primer pockets, and the brass is soft. It needs prep. When compared to my next experiment with Lapua 243 brass, it was less accurate and had higher standard deviations.

With regard to choosing some other brass and necking it up or down, it depends on what brass manufacturer you want to use, and what and how much work you want to put into it. One obvious choice is using Lapua 243Win brass and necking it up. This involves neck-turning to remove some material, but the results are excellent. Another notable choice is taking Winchester 7mm-08 brass and necking it down. The other thing people do is take their favorite 308 brass and neck it down.

I am working on getting a US source for "Lapua-quality" 260 Rem brass, but we'll see...

As far as the ballistics in my rifle, I am getting 2820fps with the 139gr Lapua Scenar using 40.7gr H4350 in necked-up Lapua 243 cases, with BR2 primers. Or I can shoot the 123gr Scenars at 3020fps with 43.0gr H4350 (it's a mild load). My barrel is a relatively tight 5R cut barrel, and some button-rifled barrels will use more powder to get the same velocity.

With higher-capacity brass, the velocity could be increased a few tens of fps, but otherwise this is about at the limit.
Click to expand...
 
Zak,
You chose the .260 Rem, was the 6.5x284 considered? The reason I ask is that I have new 6.5mm Krieger barrel that I am considering chambering in either 6.5x284 or 6.5x55, which with I have had good luck. The 284 would require a reamer and new brass, and I'm not sure it is worth the expense.
 
I ruled it out for this project because it won't feed from AI-AW magazines. The 284 case is too wide. The 260 loses about 150fps to 6.5-284, and about 100 fps to 6.5-08AI, but should have about 2x longer barrel life.

As a plug, I have an article "The Case for 260 Remington" coming out in Shotgun News in a couple months. Not exactly sure when it'll be on th shelves-- maybe April.
 
Since my targets past 200 are painted steel, I usually don't save/record results. I am pretty sure this rifle has shot 1/2 MOA @ 1000, and I think I could replicate those results in favorable conditions. I'll remember to record some next time I'm out.
 
A100_1631_img.jpg [ link to LARGER image ]

Yep, no recoil lug. The shoulder of the barrel contacts the recevier face directly. Torque to 100 ft*lbs and ready to go. Custom barrels headspaced properly can be removed and replaced just like the factory AI barrels.

Swap takes just a few minutes, and most of that is getting organized.
 
that is some nice work up , really, about the only better rounds out there right now, are the 6.5-284, or the 7mm/300 wsm. that latter fires a 180 grn bullet at 3000 fps. were talking hyper b.c. ratings here.
 
Status
Not open for further replies.

Similar threads

Zak Smith
  • Locked
Accuracy International Super-Magnum AWSM 338 (PICS)
2
Replies
35
Views
10K
Zak Smith
Zak Smith
C
  • Locked
Multiple cartridges based on the same case -- always choose 308/30-06 inside of 300-400 yards?
2
Replies
36
Views
2K
LoonWulf
LoonWulf
Zak Smith
  • Locked
A Quieter Afternoon (PICS)
2
Replies
26
Views
2K
10-Ring
1
Zak Smith
  • Locked
Photos from a weekend of long-range shooting in NM
Replies
6
Views
539
Afy
A
Zak Smith
  • Locked
6.5x47 Lapua in AI-AW Teaser Post
2
Replies
39
Views
4K
skinewmexico
S
Back
Top