A question on 5 high B.C. long range setups..

[Float Pilot]

So, using a long action for a .260 makes more sense , thereby doing away with the sole reason for picking the .260 over the 6.5x55.

Thank goodness that I am not the only one who sees that. I load for 4 rifles chambered in 6.5x55 Swede. The only thing holding me back is the weaker actions I am using.
A 6.5x55 Swede in a strong action, (M98, M700, M70) can really shine. Especially if the barrel throat length is matched up to the intended use.

I have always thought that a Yugo M48 intermediate length action would make a good base for a 260 Rem rifle using long loaded bullets.

There is a guy I see at the range every now and then who shoots a 26 inch barreled 6.5mm-06. (a 1903 action) .. That thing really flings em out there (he pushes 140 gr Bergers VLDs across my chronograph at 3,000) and he has a full five rounds of magazine capacity. It seems fairly comparable, velocity wise, to the great 6.5-284.

 

[SharpsDressedMan]

There is theory, then there is practice. Some of the other people answering your questions have noted that your data might be "overstated" on velocities achieved. I have experience loading the .308, and you are going to have to proceed slowly, watching pressure signs, and get to a chronograph. Peak velocity is not as important as not blowing a case. A 200+ grain bullet will be very long, and again, as some have mentioned, is going to take up available space in the case, if trying to stay with standard overall length. IF you go to seating the bullets out more, and single loading (as they will no longer fit the magazine), to have more case burning capacity, then you are going to need a custom throating job, or freebore. Very sensitive and technical stuff. If you try to load the bullet out more, and don't move the throat out, you are going to create vastly higher pressures by forcing the bullet into the lands before firing. This, of course, applies to all you cartridges with longer (and heavier) bullets than standard. I shoot 200+ bullets at 1000 yards, but I use a .300 Win. Mag. Much better leeway for pushing higher velocities and keeping pressure normal.

 

[Jim Watson]

I don't think the chamber throat will be a problem in a factory rifle. I frequently read of new guns with the origin of the rifling out of reach of a spitzer bullet even seated as long as possible.

And talking about magazine fit is kind of at cross purposes with a Long Range rifle.

 

[GJgo]

Yes, there's a lot of assumption here- that's pretty much all I have! I did previously own a 10FP 308 that was a great rifle- runnung Varget I had accuracy loads for 168 Amax at 2750 fps, 165 Accubond at 2900, and 180 Accubond at 2705.

I've been waffling between a couple more specific options, really. First it to get a Savage 10FP HS Precision, stick the 308 barrel in the closet, and screw on a fast twist 260 or 284 barrel from a good barrel maker. The other is to just get a Tikka T3 in 6.5x55 or 7mm-08 and call it a day. They are very different setups, I know, and that's why I've been waffling on which to do next!

 

[Maverick223]

Waffle no more...get Krieger (or your favorite bbl maker) to build you a nice .260Rem. barrel for the Savage (should have kept your old one, but they made at least two ). The Tikkas aren't bad rifles, but I think there are better platforms for building a long range, precision rifle. IMO the Savage is the best deal running for doing just that.

 

[USSR]

The only thing holding me back is the weaker actions I am using.
A 6.5x55 Swede in a strong action, (M98, M700, M70) can really shine. Especially if the barrel throat length is matched up to the intended use.

Yeah, with a strong modern action, you can load the 6.5x55 to the same pressure levels of modern commercial cartridges (60,000psi). With the 139-142gr bullets I use, I typically get 2925-2950fps from my 28" Obermeyer. What I do, is make up a dummy cartridge (sans primer & powder) with the bullet I intend to use seated so that the boattail is enclosed within the case shoulder. Then, I send it to the smith with instructions to throat the rifle based on that cartridge with a 1.5 degree leade. This allows me to chase the leade by seating the bullet out farther as throat erosion occurs.

Don

 

[BornAgainBullseye]

.308 with 155 AMAX 12" twist, or 175 SMK with a 10 twist. The latter being a battle proven combo. Sent over 1K of those downrange. Very predictable, very accurate, very known, and to those who pick up arms against our forces.... A very deadly combo. And very easy to find in commercial brands. Plus M118LR under 25 a box.

 

[lost river rat]

start with the BC of the bullets

For the best long range performance, start with the best bullet for the job. I sellect the bullet and then build the rifle for it. I look at the BC of bullets and then look at the time of flight from the cases available (the least amount of drop at 500 or 1000 indicating the lowest time of flight or highest average velocity). The BC along with time of flight and weight indicate wind deflection. Make sure your bullet stays well above supersonic to the target. This only comes into play at 1000+ yards and with the 155 .308s. Then I pick the cartride to push it. If the package is too big for my abillity, I weigh the factors and pick what I think I can shoot.

Here are the BCs for the Amax for comparison and typical velocity:

6mm - 105 - 0.500 -- 3000fps
6.5 - - 140 - 0.550 -- 2700fps
7mm -162 - 0.625 -- 2650fps
308 - 155 - 0.453 -- 2800fps
308 - 168 - 0.475 -- 2700fps
308 - 178 - 0.495
308 - 220 - Over 0.500 --(Sierra)

This should take the .308 off the table. The bullets you want to shoot (155 and 175/178) have the lowest BC and longest time of flight. You cann't drive the 220 VLD's very well and who needs the recoil? The best BC comes from the 162 7mm. Better than the 6.5. At 500 yards either the 6.5 or the 7 are excellent. At 1000, the 7 starts to pull ahead. A lot of new builds showing up in 7 RSUM and & 7WSM.

For 500 meters, shootability means more than the gain in BC for the 7-08 over the 260. If you don't want as much recoil, the 260 gets the nod. Gallager won the 2009 overal 1000 yds at Camp Perry with a .260. Would a 7mm be better, theoretically, yes. But shootability comes into play.

Looking at the BC of available bullets and time of flight along with shoot ability show why some calibers are becoming forvorites and winning.

 

[Maverick223]

.308 with 155 AMAX 12" twist, or 175 SMK with a 10 twist. The latter being a battle proven combo.

Assuming that you are referring to the M40 (M24 is a 1:11.25in. 5r twist), it was a 1:12in. twist, and shot the 175gr. SMK...the new A5 variant is purported have a 20in. barrel with a 1:10in. twist so it can accommodate heavier projectiles (210gr. SMKs IIRC), but it is not in the hands of grunts yet.

 

[GJgo]

Not to beat a dead horse, but let's look back at the 308 a little more critically- in the responses I've heard "208 at 2600 only out of a 30+" tube" and "the BC is too low".

I chose the 208 Amax for this comparison because the BC is .648, and because RL17 is getting great speeds. While I've found lots of info on it in other forums, here's an easy link for a quick verification at Midway USA. Click on Product Reviews and you see on guy with a 308 22" barrel getting 2575 and another guy with a 20 incher getting 2560 fps. With a 24" bbl & my altitude I bet it will be faster, assuming it will shoot it accurately.

Compared to the 7mm 162 Amax projectile we're talking a slightly higher BC (better in wind), 46 grains more weight (better in wind), and all else being equal probably running about 200 FPS slower (worse in flight time / drop).

If this changes anyone's ideas, post it up.

 

[padd54]

This is what I got from QuickLoad, I think it is for SeaLevel; (2540fps is the last "safe" load)

Cartridge : .308 Win.
Bullet : .308, 208, Hornady A-MAX 30712
Useable Case Capaci: 45.954 grain H2O = 2.984 cm³
Cartridge O.A.L. L6: 2.800 inch = 71.12 mm
Barrel Length : 26.0 inch = 660.4 mm
Powder : Alliant Reloder-17

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step Fill. Charge Vel. Energy Pmax Pmuz Prop.Burnt B_Time
% % Grains fps ft.lbs psi psi % ms

-10.0 90 40.08 2326 2499 43177 6368 98.7 1.501
-09.0 91 40.52 2350 2551 44583 6422 98.9 1.479
-08.0 92 40.97 2374 2604 46037 6474 99.1 1.458
-07.0 93 41.41 2398 2656 47541 6522 99.3 1.438
-06.0 94 41.86 2422 2710 49097 6568 99.5 1.418
-05.0 95 42.30 2446 2763 50708 6611 99.6 1.398
-04.0 96 42.75 2470 2817 52376 6651 99.8 1.379 ! Near Maximum !
-03.0 97 43.19 2493 2871 54083 6688 99.9 1.360 ! Near Maximum !
-02.0 98 43.64 2517 2925 55891 6721 99.9 1.341 ! Near Maximum !
-01.0 99 44.08 2540 2980 57744 6752 100.0 1.322 ! Near Maximum !
+00.0 100 44.53 2564 3035 59665 6779 100.0 1.304 !DANGEROUS LOAD-DO NOT USE!
+01.0 101 44.98 2587 3091 61658 6804 100.0 1.287 !DANGEROUS LOAD-DO NOT USE!
+02.0 102 45.42 2610 3146 63723 6828 100.0 1.269 !DANGEROUS LOAD-DO NOT USE!
+03.0 103 45.87 2633 3202 65865 6851 100.0 1.252 !DANGEROUS LOAD-DO NOT USE!
+04.0 104 46.31 2656 3258 68090 6873 100.0 1.235 !DANGEROUS LOAD-DO NOT USE!
+05.0 105 46.76 2679 3315 70402 6895 100.0 1.219 !DANGEROUS LOAD-DO NOT USE!

 

[GJgo]

Of course then you start looking at things like Lapua brass (tougher, more consistent) vs. Winchester brass (more powder capacity, purportedly therefore faster)...

Good info, thanks!

 

[GJgo]

Here's an in-depth thread on another forum for anyone interested more in the 308 combo. Lots of good info, lots of pages. Don't take my word for it- check out what guys are actually doing.

 

[Maverick223]

Don't take my word for it- check out what guys are actually doing.

...but they are using Surgeon and AI actions...do you plan to do likewise? I am not saying that a commercial action will not contain it, but I would feel better about pushing bullets that fast if I had a really strong, well-made action and a barrel with a long chamber to accommodate the really long OAL that they are using (a whopping 3in., SAAMI standard is 2.8in. for the .308).

 

[GJgo]

I finally made a decision here, thought I'd let you guys know. Thanks again for all your help.

I decided to get the action and the stock I wanted, since barrels, in the long term, are a consumable. I picked up a Savage 10FCP HS Precision 308. The accutrigger on minimum breaks at a clean 1.5 lbs.

I glass bedded the action & recoil lug- even in the aluminum bedding cradle, it only touched the action at 2 points, along each side, both in the front & rear. (see pic of front) Not any more! I also glass bedded a 20 MOA Warne rail onto it. I then topped it off with a SWFA SS 16x with a set of Burris XTR low rings.

I plan on shooting it for now since I'm fresh out of budget. In the future the plan is to have a good barrel made in 260 or 284.

 

[Dr. Tad Hussein Winslow]

If you DO shoot bullets that heavy in a .22-250, it will have to be a Savage LRPV or custom barrel, for the right twist.

The answer is .260 rem, with .243 close behind, and 7mm-08 close behind that. IMO.

 

[Dr. Tad Hussein Winslow]

Float pilot...

It seems fairly comparable, velocity wise, to the great 6.5-284

Yep, my reload manuals shows that the 6.5mm-'06 bests the 6.5-.284 Norma by a good 50-100 fps, across the board!

Gjgo, I see you've made your decision - congrats - you'll enjoy that rifle!

 

[Jim Watson]

GJgo, I think you made a good move there. By the time you wear out the .308 barrel, you will have a lot better idea what to replace it with. Might even be another .308.

Tad, from what I read, LR shooters tend to underload the 6.5x284 a bit anyhow. There seems to be an accuracy sweet spot around 2950 fps.

I hear of some movement towards 7mm, in the WSM or good old .284 chambers. Super high BC and not as much kick as a big .30.

 

[GJgo]

Looking around Midway, they have drop-in Shilen barrels for the Savage in 260, 8 twist. I've heard good things about these barrels, so this might be the answer!

 

[Maverick223]

I think that may be the best route, GJgo, Shilen makes a good barrel (though I favor Krieger).

 

[cz85cmbt]

I'm not so sure that the 7mm-08 is really accurate with 160 grain bullets and over. Remingto tends to under twist their barrels. The 260 originally came out with a 1-10" twist and could only stabilize 120gr bullets consistently. most are 1-9" now. The 08's twist is not very fast and I think was intended for 140 grain bullets. 7mm bullets have excellent bc's but you can get 154, 144, and 142's that rival or exceed the 7mm. Also be careful bc's is not universal it is dependent upon velocity so a bullet will change it's bc while in flight. I would go .260 but outside of your choices I'd go 6.5 swede in a tikka.

 

[Zak Smith]

.243 with the right bullet and shot fast can beat .260 at 1000+ yards (and in between); although the BC is a little bit less, 200+ fps more muzzle velocity makes up for it (just like how the 155 Lapua Scenar can beat just about all heavier higher BC bullets due to its higher MV). However, the downside is less than half the barrel life and less terminal effects, which can matter even in matches on steel targets. 7-08 doesn't have enough powder volume to shoot the 160's fast enough to make good use of the high BC value, compared to the .260.

Of those choices, the .260 is the sweet spot in the .308 case size. I have a hunch that a high-BC .25" caliber bullet in a .25-08 might be a slighter sweeter spot, but I've never tried it.

For hunting, I'd probably got 7-08 or .260.

With RL17, 2900-3000 fps is achievable with the 139-142's in .260.

With the old 2800 +/- 40 fps .260 loads, 4000+ rounds was a reasonable barrel life. I am actually still on my original .260 barrel.

I know a 6.5x47 shooter who burned out his barrel in under 4000 rounds, but he was loading to excessive pressure.

 

[MTMilitiaman]

I may be running against the pack here, but my first choice would be the .308, though I probably wouldn't be running anything over 190 grains. The 155 Scenars look mean. The factory published BC is around .500, right up there with the 175 gr SMK, IIRC, but most loading data available for it gives it a solid 150 fps more muzzle velocity, depending on barrel length. I've been considering this bullet for when I finally get set up for handloading for my M1A, and even with the restrictions placed on powders and such loading for the gas gun, it looks like loads are readily available that will keep this projectile supersonic to about 1200 yards. Plus, if all else fails, commercially available match loads are abundent, and just about everything that can be known about the 168 and 175 gr SMK is published somewhere--despite the inferior paper ballistics of either of these loads, I think having a known reliable performer with plenty of data available goes along ways.

Beyond that, I would probably look into the Creedmore, rather than the .260, due to its advantage handling the longer, heavier for caliber match bullets available for that caliber.

 

[Zak Smith]

Beyond that, I would probably look into the Creedmore, rather than the .260, due to its advantage handling the longer, heavier for caliber match bullets available for that caliber.

This is a fallacy. See my post over here for why
http://www.thehighroad.org/showpost.php?p=6268520&postcount=8

ETA: I did add a "conclusions" section to my 6.5mm Shootout article last fall with relevant comments about the cartridges.
http://demigodllc.com/articles/6.5-shootout-260-6.5x47-6.5-creedmoor/?p=5

.308 is a compelling choice for the long-rang shooter who does not reload; however, when he decides to upgrade to shooting the 155 Lapuas at 2900+ fps, he will still be at a palpable disadvantage to the folks shooting the 6.5's and 7's. One anecdote I have on this is that Ray Sanchez shot the 2008 Steel Safari with his .308 (Surgeon approx 24") shooting the 155's at over 2900 fps. He shot great but came in 7th overall; however, he was "high 308". In 2009, he shot a 7mm WSM and won. In 2009, the top 308 shooter, who was having a great day, shot to 7th place also.

The .308 does have a lot of things going for it, but for a purpose-built long-range rifle, the .260 runs circles around it.

 

[MTMilitiaman]

Informative as usual Zak. I stand corrected.