I had my Ruger All-Weather 260 Rem re-chambered to the Ackley Imp by Ray's Gunsmith Shop in Grd Jct CO. He did a frist rate job too.

Preliminary Chrono results were: The 140 Rem Express factory in Imp chamber ran about 2600fps
46grs IMR4831 140 Nosler was 2807fps
49.5grs RL 22 140 Nosler was 2989fps--with slightly flattened primers. Intend to back off 1 grain and Chorno and put on paper. IMR4831 will also do some paper work.

Now that is impressive IF the pressures are safe.

I know the 708 and larger bores seem to gain little, the AI in 260 may do much more in way of improvement.........

AT the cost of further barrel wear from what I have been informed.

476NE,

I like the 260 its a slick underestimated little round and people could say what need is there for one like they say about the 338/06, cause they are jammed in between other popular cartridges. But they fill a very usefull niche.

The low Vel. you got with the factoryRem140 does not surprise me, other people have told me that they found it to run much short of published factory velocities.....However the improved data for the 140(2989fps?) really surprises me. As a matter of interest:
What was the max. vel you were achieving with the 140nosler/RL22 before improving the std.260 chamber? I cannot see where improving the std260 can give that much more boiler room space to give such a high vel. A 250Sav has substantial body taper, so i can see where the great improvement comes, with the 260,i cannot.
I presume you still have 22" barrel?
IF I could get a std260 to reach 2850/140gn without too much trouble, then I would give away my 270 and get anice 23" barreled 260 rig.

I did not fire anything in it prior to the re-chamber job. When I feel better and it warms up here, I will fire groups and chrono those loads.

I have a M700 in .260ai w/ 1-8 PacNor bbl. It thrives on med. to slow powders w/ 120gr-142gr bullets. Give IMR7828ssc a try w/ 140gr bullets. A great little cartridge. I use RP.260 brass & Lapua .243 necked up.

Impressive stuff 4 sure and I find it very interesting. I am on the brink of getting a Montana in 260 and have giveen thought to punching it to AI.

It will be a great lil rifle for my wife to use here and well, I may just use it a bit to...

Fred have you done any clock work with yours?

Thx

Mark D

Mark, I'm running a 27"bbl. on mine, target/varmint rig (although I did take it to Montana as a backup last year on an antelope hunt, just in case). My best loads so far are:
46.5gr RL22/142grSMK = 2850fps+ 1/2moa
48gr 7828ssc/142grSMK = 2900fps 1/3moa
The 1-8 does well w/ all bullet weights.
50gr 7828ssc/123grLapua = 3100fps 1/3moa
46.5gr H4350/123grLaua = 3100fps 1/2moa
48.5gr RL19/123grLapua = 3050fps 1/2moa
For varmint loads:
44.5grVV150/85grSierra = 3400fps 1/3moa
It's worked out so well I've been thinking of getting a doner rifle & having it rebarreled for a lt.wt. deer/antelope rig. Could even stretch it to cow elk under 250yds w/ a good 140gr, but then what would I do w/ my .338-06?
BTW, I've been reloading w/ a set of Lee neck dies for the .260, they seem to work fine. I get about 11-12 reloads before the brass gets thick & chambers w/ difficulty. Brass is cheap though so no worries.
476, I started getting pressure signs @ 47gr RL22. The 7828ssc w/ a drop tube seems to get me the best combo of vel./pressure & accuracy w/ 120-142gr bullets. My rifle likes VV150 & RL15 for 85-100gr.

thanks for the info Fred, and by the way IMO you could stretch that rig a whole lot farther for elk.

With the right bullet I would have no qualms about shooting one at 500 with that rig.

Mark D

quote:

49.5grs RL 22 140 Nosler was 2989fps--with slightly flattened primers

Amazing.....almost equal to the .264 Win mag loads shown in my loading manual.

I sure wish I knew the pressure it's generating.....but then it's your gun...

Best of luck and go get that elk.

Maybe Mark, but I know I can get closer.

476NE, nice work. I'd be real happy getting the 130 Scirocco close to 3000 fps much less a 140. Could you fill one with water and weigh it? I was under the impression that improving the .260 only added 3-4 gr capacity.

Not even that B-F. RP cases show only 2gr on the avg. The case looks very cool though & you almost never have to trim.

This will be entirely my opinion and last time I checked that wouldn't buy you much.

While I haven't played with the 260 I have played with the 243 & 7-08 along with their AI versions in the same barrels. In the case of the 7-08 it was with a strain guage attached. Using the factory chamber and factory loads to establish the starting point. At the same pressure the 2 gr increase in capacity gave the expected 1% velocity for each 4% capacity or about 25-40fps.

I have no reason to doubt your velocity claims but in my opinion they aren't coming from changing the shoulder angle and adding 2grs of capacity. The 260 is only loaded to a max of 60,100 factory. Your gains are coming from a much higher pressure, longer barrels and using a drop tube to pack the case with slow buring powders. All of which could be done with the normal 260 case.

Look at your loading books. For a given powder & case the relationship of amount of powder, pressure and velocity is a linear function. Hornaday for example in my manual points out that is how they develop their tables it is the same way the computer programs are made. For the 260 case 140 nosler and IMR 4831 you gain approximately 15fps for each 1000psi. Sure there will be some variations. That is why they all say work to the max with caution.

Your velocities are greater than the 6.5Rem Mag the 6.5-06 and all but the top load listed for the 264Wmag in my Nosler book. 2grs of capacity just won't give you that.

Like I said I don't doubt you are getting those velocities and if you feel comfortable using them then go for it.

I've played with numerous AIs and my own improved Gibbs from 243 to 416 over the last 30+years. I own far more wildcats than I do factory. But there isn't any free lunch. All my work and playing just verified at the same pressure you get approximatly 1% velocity gain for each 4% capacity (powder) increase.

There that is my soap box for the day time for coffee.

Ramrod340,
All true. But the beauty of knowing that the Chrono read 2989 with a 140 nosler and the bolt lifted, the case fell out and the primer was slightly flattened, is that one can drop back a grain like was in 476NE's note and still run 2800+, a very nice load. That and the case is cool, don't have to trim but once in a blue moon and it's fun to play with. Thank goodness for folks who don't settle for the standard case as they are the same ones sustaining the gun makers by buying guns they don't "need."

First, the water capacity of the imp Rem case is 56.7grs to 56.8grs.

I figured there would be some dubiety over my results, I was suprised myself. The RL22 is probably about 1 gr over, though in this short preliminary chrono tests I did not measure head expansion, I will when I do additionaly tests.

I dont have any 7828 to test but would bet it would do as well as RL22. As an earlier post relates, the very slow powders seem to be the ticket with this cartridge. And, no, I dont beleive the 40 degree shoulder has anything much to do with it. The 260 Ruger may have a fast barrel. This is the only one have messed with. I will hazard a guess that 48.5 grs of RL22 will run about 2900 in this 22 inch tube.

If my veracity is in doubt, kudu56 will verify same as to veracity, and Ray Atkinson and I have a mutual friend in Boise Id Ive known for 26 yrs plus. Ask Ray to contact Paul Broyles in Boise for a veracity check on me. Fury01 a member here too has known me for 40 yrs, contact him.

Ive been an inveterate shooter and hunter since 1968, have used 3 or so imp versions over the years, and have a large collection of sporting arms at the moment and a long time in the past.

No, I dont think the 40 degree shoulder has much to do with it, maybe it has a fast barrel, as this is the only 260 Ive messed with. I would hazard a guess though, that 48.5 grs of RL22 will get about 2900 fps.

Since I dont know what a std 260s water capacity is, I cant calculate the % of increase.

I think too that as IMR4831 showed no signs of excess pressure, 47 grs would turn out about 2900fps too.

I hope this helps

quote:

First, the water capacity of the imp Rem case is 56.7grs to 56.8grs.

243 and 7-08 AIs have each given me right at 2 grs more water capacity. If you want maximum capacity use Norma 243 or 308 brass. I have always found Norma to give about 2-3 grs more water capacity in the parent case. I only use Norma if possible. What I have found is I start getting a little head expansion at 65,000 in numerous Norma cases. So if I can I use Norma brass measure each load when I get expansion I take that to be 65,000 and back off a gr and call that max.

I have a Ruger 260 standard rifle that I have shot quite a few 160 Hor RN's in over a load of 4350. Chrono-ed at 2650 the velocity alone gives measure that it is a high pressure load. However; as stated by many, the round as loaded in this gun is safe and repeatable and I used it for a couple of years. Last year just for fun I dropped 45 Grains of H-4831SC into the case and have not bothered to Chronograph it yet. It still killed whitetail rather well though. I am going to use 140's Remingtons for practice and probably to shoot another whitetail or two next year knowing full well there are better bullets. Or: might use the Nosler Partition like 476NE just for fun. Hopefully I can get 476NE out here to shoot whitetail with me next fall. I want to see if the 260AI kills anybetter than the 416 Taylor he brought last time! Perfect shot and the buck still ran 80 yards. (normal for those of us who have been shooting deer for many years yes?)

FredJ338, A question if I may intrude. What is the loaded round neck diameter of the .260 when using the Lapua brass? Thanks in advance.
Dave

As best as I can measure w/ the calipers I have, 0.291"-0.292". It's 0.290"-0.291" for the RP260 brass.

Thanks Fred

Just fired a few over the screens. the 160 RN with 45 gr or H-4831sc were 2558fps. the 140's with 46.5 gr of AA-3100 were 2570fps.

I have a 260 A.I. with a 25" barrel (cut the entire chamber out of a 6.5 X 284 F class rifle that I was sick of fooling with) and had it rechambered in 260 A.I. The velocities that 476NE tells of are acheiveable. I use 43.6 gr. of H4350 behind a 142 MatchKing ignited by a CCI BR-2 primer in Rem. brass for 2866 fps avg. I have 11 firings on the brass and the primer pockets are still good and tight. Bolt lifts easy, no primer flattening.

Late last fall at the end of the match season I did some testing with a load of 48.3 gr of H4831 SC behind a 142 MatchKing again in Rem. brass ignited by a Fed. 210M that produced accuracy equal to the H4350 load. Avg. velocity for 20 shots was 2932 fps. Like the H4350 load there were no pressure signs what so ever. Yes that kind of performance is possible out of a 260 A.I.

I have used the 260 A.I. for the past 2 years in 1K F Class matches and feel I give up very little to a 6.5 X 284 and enjoy much better barrel life with a less finicky round. That is why I went to it instead of the 6.5 X 284.

PaPa 260....May I Be Half The Man My Grandsons Think I Am

Papa, another of my favorite loads is 43grH4350 under the 139grLapua. Vel. runs just above 2800fps & on good days will shoot in th .3s. It's a nice little cartridge giving good case life & quite a bang for the buck.

Guys, I have shot the 260 a good bit and I believe the 6.5 bore is VERY efficient in a medium capacity case, as the magnums have a quickly diminishing return likely due to the smaller expansion ratio (small surface area on the base of bullet combined with smaller internal bore area to burn powder)

AND the longer shanked high sd bullets that gives more friction in the bore, yet sheds velocity slowly due to high bc in the air.

Longer barrels and slower powders seem to often get the most on performance in 6.5's with 120-160gr bullets.

I still have heard the bore life on the AI is less than std.

It is a factor to me, but I hear so many good things on the Ruger's in 260 with proper 8 twist, I may have to try one some day. The gun would be less than a barrel job.

quote:

140 Nosler was 2989fps

That velocity exceeds four of the five maximum loads in Nosler #5 for the 264 WM from a 24" barrel.

The maximum load in the 264 WM using RL 22 and the 140 gr bullet is 59 grs at 2929 fps.

I did mean to say earlier, many custom barrels can go faster, and those 264 M loads may could be bumped, BUT Savage99 makes a great point.

I would believe anything over 2850 or so, unless a really long barrel is used, is getting up there with a 140 I believe.

A 270 does about that, but 10 twist, short bearing surface bullets, and more powder capacity, of course a small increase in surface area on base of bullet and bore volume.

I have shot and continue to shoot the standard 260 a lot. Matter of fact I have 3 rifles chambered for it. My match rifle that is chambered in the standard 260 is nearing the end of life for the second barrel. The first barrel was pulled after 2,617 rounds. The second will go about that. Judging from the throat erosion I have on the 260 A.I. after 1,829 rounds I am projecting an accurate barrel life of some where around 2200 to 2400 rounds for this Krieger barrel. Yes, it does look like the 260 A.I. will get slightly less accurate barrel life than the standard 260, but is far better than a 6.5 X 284. For whatever it is worth all the barrels both standard and A.I. are and have been 1 in 8 twist Kriegers. Just my observations so far.

PaPa 260.....May I Be Half The Man My Grandsons Think I Am

I shoot almost exclusively the 129 Hornady in my 600 263 Express. [Same as 260] I tried the 140s but figured the velocity of 2850 or so not what I wanted and went to the 125 Nosler and 129 Hornady. Both of these give a litle more velocity and about the same killing quality. I still use the 140 Gamekings in my 264 Mag and most likely always will.

Aloha, Mark

BTW B-F, the RP260 brass has approx. 2gr greater case cap. than the Lapua, vel. run about 40fps less in the RP w/ the same loads.