260,260ack or creedmoor

[gbal]

Yep.....at least until another cartridge comes along that does the same thing as the other 3.....then get that

The 6.5-08 A Square,if you think three are enough already.

[John MH]

That's what God helped by the Swedes made 6.5X55mm for!

Yes, but that won't fit in a short action.

[Laurie]

True - but is the extra bit of bolt manipulation really a handicap in tactical comps? P-H M85s, M87s etc still see use in CSR and they have a full-length Mauser '98 action. There is a YouTube clip of a Scandinavian guy shooting 6.5X55mm in their Stangskyting discipline, and it seems pretty fast to this non Tactical type!

 

http://bulletin.accurateshooter.com/2012/04/scandinavian-bolt-rifle-speed-shooting-stangskyting/

[John MH]

Availability of 10 round magazines is the main issue with the long action. As most tend to go for some sort of Remington clone these days and the choice of 10 round magazines forces many down the AICS route, or some of the other DBM options, but most use AICS magazines.

[Laurie]

Availability of 10 round magazines is the main issue with the long action.

 

 

yes - a good point. I hadn't thought of that.

[Swarovski1]

Thanks a lot for all your input, sounds to me like 260 is the way to go, what realistic velocities could I run the 260 with 139gr scenars,140gr bergers or 142gr smks and get good case and barrel life, I can run my 6.5 06 at 3000fps shooting slow but range workdidnt suit that velocity, wound it back to 2860fps and I can shoot as fast as I like without a sticky bolt, atb swaro

[Hatzi]

2800-2850fps seems to be a popular region for the 139's in 260's but in my gun that is actually 2 grains (H4350) away from any pressure signs and my cases just go on and on.

[Borisserge]

Can you use Lapua 308 palma brass for your 260 to give the benefits of small primer etc the same as the 6.5x47?

[Deeredriver]

I've just started using a T3 rebarreled in .260AI.

I'm currently getting 2860fps with 139gr Scenars with fire forming loads which are shooting into sub half MOA.

I finally decided on the AI so I could shoot 139-142grs out to 1000yds plus at 2900-2950fps, luckily the donar action was a 6.5x55 so I can seat the bullets fully out to gain the full benifit of the case capacity. The reamer used had free bore to suit the 140 class bullets.

[mildot]

im running a .260 with 142smk's last time I borrowed a chrono they cloaked 2770fps out of a 30" tube. however if I use trajectory validation on strelok with my 300yd drop it says velocity is about 2808fps, but then my rough 1000yd drop is wrong! however this is because its a rough drop that I allowed me to hit a fig 11 target so not an accurate gauge of the correct drop. Im working on my fine tune loads and will hopefully borrow a chrono to test them in the next couple of weeks.

[Laurie]

 

Can you use Lapua 308 palma brass for your 260 to give the benefits of small primer etc the same as the 6.5x47?

 

I've seen this question posed on several forums, but never seen an answer from anybody admitting they've done it and advising how any results work out. Yes, you can re-form 308 to 260 Rem, but it's a lot of work and Lapua makes superb 260 brass, so it's purely a small primer issue.

 

The benefits would be reduced velocity spreads (maybe!) and a very strong case-head that let's you load the cartridge up to pressures beyond what SAAMI / CIP would consider wise. With annealing and reasonably sensible loads, these cases would likely last forever - but so does standard brass.

 

The main downside apart from the work involved is that the small primer / flash-hole set-up only gives marginally efficient ignition for 308 Win charge weights of easily ignited powders like VarGet. While most 260 Rem loads have smaller charges (~40gn v 46-47gn), they involve slower burners on the whole (N150 / 4350 and this may make the primer's task a bit harder. There would almost certainly be no problems in summer, but performance could go downhill (both MV levels and spreads) on a fairly normal winter's day just above freezing, and cause big problems in very cold weather.

[gbal]

Can you use Lapua 308 palma brass for your 260 to give the benefits of small primer etc the same as the 6.5x47?

 

 

I've seen this question posed on several forums, but never seen an answer from anybody admitting they've done it and advising how any results work out. Yes, you can re-form 308 to 260 Rem, but it's a lot of work and Lapua makes superb 260 brass, so it's purely a small primer issue.

 

The benefits would be reduced velocity spreads (maybe!) and a very strong case-head that let's you load the cartridge up to pressures beyond what SAAMI / CIP would consider wise. With annealing and reasonably sensible loads, these cases would likely last forever - but so does standard brass.

 

The main downside apart from the work involved is that the small primer / flash-hole set-up only gives marginally efficient ignition for 308 Win charge weights of easily ignited powders like VarGet. While most 260 Rem loads have smaller charges (~40gn v 46-47gn), they involve slower burners on the whole (N150 / 4350 and this may make the primer's task a bit harder. There would almost certainly be no problems in summer, but performance could go downhill (both MV levels and spreads) on a fairly normal winter's day just above freezing, and cause big problems in very cold weather.

Thanks Laurie-sounds like 'no free lunch',as usual, for the necking down.

Has the small primer Lapua 308 Palma brass made any worthwhile improvement over the large primer lapua 308 brass in competition,or any that would reasonably trickle down to club shooters etc?

Gbal

[Laurie]

It's very widely used in F/TR George. I was initially sceptical for 155-185gn bullets and some early 100yd winter tests that I did at Diggle suggested these cases are powder + temperature sensitive. For instance N150 + 155s worked fine in 3 or 4-deg C weather, but N140 was poor (large ES values). Rerunning the N140 trial in the spring at ~12-deg sorted the problems out. This suggested that they might not work that well if it's colder than maybe 5-deg C, but not with every powder.

 

What I and others soon found was that they work VERY well with heavier than 200gn bullets in 308 Win with high-energy powders (N550, Re/Elcho 17). You can safely achieve velocities where the equivalent Lapua large primer load blows the primer .... then go onto higher MVs from there. Note that I say 'equivalent', by which I mean in MVs as the small primer brass drops any combination's MV by 35-45 fps over standard brass and you need to adjust charges up slightly in response. So I had side by side tests with Lapua LRP brass where I'd blow the primer in the latter at say 2,800 fps while going onto 2,830 fps with the 'Palma' case without problems. Both types have identical internal capacities and same thickness necks, so it's apparently purely a primer size + flash-hole dia. (Palma is 1.5mm / 0.059" v 2mm / 0.080" in standard cases) issue.

 

So the guys who shoot 210s to 230s at the top of the GB FCA league now use Palma brass without exception and I believe this is the norm in Match Rifle too these days where people run even higher MVs in super-throated chambers.

 

There are various views about all this. The sceptics / predictors of imminent doom say that people are simply running proof-house pressure loads all the time which the cases both stand up to and mask the normal over-pressure symptoms, so it'll all end in tears. Others, myself included, believe that the small primer and CRUCIALLY its alliance with the small diameter flash-hole is changing the 308 Win's internal ballistic characteristics for the better. I'm convinced it changes the initial burn pattern flattening the peak of the pressure curve somehow.

 

That's with heavy bullets. I didn't see any great benefit initially with 155-185gn bullets but have become converted over time. No doubt that these cases do provide excellent performance with 155s and H. VarGet, H4895, and IMR-8208 XBR (not really an IMR powder as it's made for Hodgdon in Mulawala, Australia alongside the ADI / Hodgdon numbers not in Canada with the old-established IMR grades). Single figure ES values are attainable in a good load in prepped brass while the equivalent runs in the mid to high teens with similarly prepped LRP Lapua cases. So again, all the guys 'in the know' have switched - I think the entire GB F/TR team at Raton used Palma brass.

 

I was surprised too to actually get better results (smaller groups and ES) with H414 ball powder in side by side tests with 185 berger Juggernauts and LRP Brass. I'd been sure that any ball powder would work better with the more active and powerful large primer.

 

Palma brass is also what made me reevaluate the annealing issue. Standard Lapua or Norma brass starts to see primer pockets loosen at around five firings with heavy loads, so cases would be junked or reallocated to light loads, testing and suchlike with new cases replacing them for long range matches. Palma brass just goes on .... forever, it seems. So, if the back end stays 'tight' and close to its original factory dimensions, the limiting factor becomes work-hardening in the neck and shoulder, even with minimum-SAAMI specced chambers and minimal working during resizing with well matched bushing sizes etc. I know of people who've fired 12 or 15 heavy 210gn loads in Palma brass and it's still apparently perfect - so regular annealing has to be essential to retain benchrest levels of accuracy with this sort of use.

 

There are two issues people considering Palma cases must be aware of. One is that small primers + high-pressure loads can produce badly cratered / pierced primers if the rifle's firing pin is a poor fit in the bolt-face and/or the mainspring is on the weak side. So, running warm loads in factory remington 700s or similar may not work out as well as the shooter had hoped. (This applies to other cartridge designs using the combination - PPCs, BRs, and 6.5X47 Lapua - as well.) Also, for this reason, SR Magnum or BR should always be used. They're not only needed to cope with 40+ grain powdewr charges but have thicker cups than standard SR primers.

 

Second, you MUST get the proper dia. decap pin and replace that provided in 308 Win dies which is dimensioned to suit the 2mm flash-hole. using a standard decap pin (or the Lee etc decapper die) will likely see the pin break or stick in the flash-hole. With the very strong Lee decapper set-up, you'll swage the flash-holes larger. Likewise, if flash-hole uniforming is done as part of case preparation, the correct size of reamer must be used. Sinclair International's uniformer reams the hole out by two thou' to 0.061". Tests have shown in 6mm BR and similar that group size and ES values increase if the flash-hole is reamed to ~0.070" or larger and this likely applies to 308 Win Palma brass too.

[dannywayoflife]

Excellent info there laurie thanks as always. It's great to have such knowlage on the forum!

[Swarovski1]

Yes laurie that was some write up but I need it in plain English, that just complicates things for me,I read an article on 6mm br thing about a 260ai terry somebody shooting his ai at 2900fps plus, what I don't understand is his was a 1 in 8.5 twist, why a 1 in 8.5 twist, why not 1 in 8 twist

[jcampbellsmith]

1:8.5 works. That's the twist I've currently got. The Terry Cross article is 7 years old. I don't believe he bothers with the 260 AI any more. I'm sure I read a match report of him shooting recently with std 260 Rem. You could always e-mail him and ask his opinion.

 

http://kmwlrs.com/SENTINEL

 

Regards

 

JCS

[Laurie]

Well, that's part of the fun with the shooting sports (and even more of the expense) - the constant experimentation, and discussing all the theories, crackpot or otherwise. I read just the other day that lots of (two or three?) people have decided that 1-7.2-inch twist is THE rate for 90gn VLDs in long-range 223, 22BR etc. Next week somebody'll say it's 1-7.3 and if he wins a few matches, everybody with 1-7 and 1-7.2 barrels will start to worry about not having the right spec kit, and think about switching to it.

 

The trouble, or more likely the good thing, about shooting today in the 21st century is that we're spoiled for choice. I regularly marvel how much gear I take to the range and how long it takes me to unload it all compared to when I started.Then, some Diggle greybeard will tell me that he can remember talking to even older shooters from the area going back to when it was still a military range, Diggle station hadn't been closed by Dr. Beeching and more than a few shooters came with their 303 Number 4s by train and walked up to the range and back again at the end of the day. (No doubt catching a late train home too after a good session just up the road in the Diggle Hotel.)

 

They'd find it incredible, and might be envious too, that we can debate which of three 6.5mm cartridges is best and can consider custom rifles with 80-power scopes to use them in, have a choice of 15 or whatever bullets to load, and put 19 or 20 shots into a ring the size of a dinner plate at 800, 900, or 1,000 yards.

 

On the other hand, they might say we've taken all the fun out of shooting - better to use cheap / free 303 Mk7 ammo, hope you've got a good lot, and go down the pub rather than spend evenings neck-turning brass and handloading ammo!

[Swarovski1]

The know how and technology is phenomenal these days, I know what you mean about the experimental, theories and expense is all part of the fun, maybe you the man for advice on my 6.5 06, why am I not being able to run mine to around 3000fps with 139gr scenars or 142gr smks without pressure signs and sticky bolts in rapid fire shooting, I use remy brass, n160, fed match gold primers,all loads single loaded, they chrony well, ive tested same bullets with imr 4350 with 0.5grs less powder but only for accu at 1000yds which were exellent, will be trying some h 4831sc shortly

[Laurie]

Swarovski,

 

6.5-06 isn't a cartridge I've ever had dealings with. You don't say what barrel length you're running as 3,000 fps in any 6.5 with 139-142s isn't as easy a 'target' as it might seem unless you're up at the 30-inch mark.

 

N160 (likewise N150 for the smaller case 6.5s) is a great powder for such applications, but I have noticed a tendency for pressures to spike rather rapidly, so it's one I'm always a bit wary of really loading up to the limits. What's fine on a cool testing day might blow every second primer and cause a rapid withdrawal on another, maybe warmer one.

 

I did have a look at 6.5-06 on QuickLOAD with the 139 Scenar, and one thing quickly struck me - how the rifle is throated and therefore what COAL you're running the cartridge at. Sticking to the parent .30-06's 3.340-inch which is presumably pretty well mandated by action / magazine dimensions in many repeating rifle applications sees the bullet seated VERY deep in the case with a considerable effect on the fill-ratio and peak pressure with single-base powders like N160.

 

At a COAL of 3.340", QuickLOAD reckons that 3,042 fps is attainable with N160, but from a 30-inch barrel. That's with a heavily compressed load getting on for nearly 5% over-fill as the bullet has 0.61" of its parallel shank inside the case. Take the COAL out to 3.550" which still has the 139 seated fairly deep (0.398" of shank in the neck) and the charge can be increased by nearly 2gn to give 3,065 fps (estimated - all usual caveats apply!).

 

I ran a QL Propellant Charge Table for the cartridge and 139 at 3.340" to see what sort of powders might exceed 3,000 fps. The input parameters specified 60,000 psi PMax, 30-inch barrel, 3.340" COAL, 105% maximum fill-ratio allowing compressed charges.

 

Ignoring Somchem and Bofors etc powders we don't see, we get:

 

1. N560 .............. 3,153

2. IMR-7828ssc .. 3,138

3. Re22 .............. 3,124

4. Re25 .............. 3,090

5. Re19 .............. 3,075

6. H414 .............. 3,061

7. H4831sc ........ 3,052

8. Re17 ............. 3,039

9. N165 .............. 3,018

10. Ram B Game 3,007

11. H4350 .......... 3,003

12. Lovex SO70 3,003

13. N160 ............ 3,003

 

(SO70 is better known as Accurate-4350 here, and is still available.)

 

That's with a 30-inch barrel remember, so comfortably exceeding 3,000 fps is no easy matter. Unsurprisingly, double-base or high-energy powders such as N560 and the Reloder series predominate as the extra specific energy is required to get the velocities. They won't do much for barrel life though, especially in rapid fire.

 

Another thing that struck me is 6.5-06's nominal PMax as listed in QL is a very high 63,091 psi by the Piezo transducer method and A-Square as the 'authority' as it's not a SAAMI or CIP registered cartridge.

 

I'd be wary of running a cartridge based on the '06 case up to 63,000 psi, hence my inputting 60,000 into the QL request. 63,000 soon becomes 65,000 + with minor changes and I'd wonder how long Remy brass would last at that sort of regular pressure.

 

I'd have to say that if I were having a 6.5mm repeater built for this class of cartridge, I'd use 6.5-284 in a long action with the bullets seated out. Running QL again with the 139gn now at 3.100-inch + 105% F/R and 60,000 psi PMax, you reduce fill-ratios to the 100-102% level with a lot of powders and gain around 30-40 fps MVs over 6.5-06. But again with a 30-inch barrel showing it's marginal as a 140gn / 3,000 fps cartridge in shorter barrel rifles.

[Swarovski1]

Its t3v action with 1 in 200mm twist 26 inch varmint deep fluted profile barrel,its tight chambered,you certainly have learnt and know your stuff mate.sounds like you have forgot more than I know, ive a mate with similar knowledge, I am always willing to learn, I am getting exellent accuracy from it at 1000yds, there is a saving on windage with that extra 150fps which I could benetit from, ive always been a 06 fan and was an experiment, was a toss up between 6.5x284 and my 6.5 06

[Laurie]

With 26 inches, you lose 100 fps or thereabouts over a 30. Running at 62,000 psi, (still within allowable pressures, but getting very high) QuickLOAD suggests you can exceed 3,000 fps with Viht N560 and Alliant Re22, both high-energy powders that will soon knock the stuffing out of your barrel. The only single-base powder that is up there is IMR-7828ssc, originally developed in the 1960s specially for Remington to get the prototype 7mm Rem Magnum up to the desired speed.

 

H4831 in either form is a bit below, but almost makes 3,000 fps, so that and 7828 look like the two to experiment with - I'd get your ordser in now though as they're both unobtainable right now so far as I know.

[The Gun Pimp]

its tight chambered

What does that mean?

[DaveT]

With 26 inches, you lose 100 fps or thereabouts over a 30. Running at 62,000 psi, (still within allowable pressures, but getting very high) QuickLOAD suggests you can exceed 3,000 fps with Viht N560 and Alliant Re22, both high-energy powders that will soon knock the stuffing out of your barrel. The only single-base powder that is up there is IMR-7828ssc, originally developed in the 1960s specially for Remington to get the prototype 7mm Rem Magnum up to the desired speed.

 

H4831 in either form is a bit below, but almost makes 3,000 fps, so that and 7828 look like the two to experiment with - I'd get your ordser in now though as they're both unobtainable right now so far as I know.

Laurie

 

Can you help me with the issue of reputed accelerated barrel wear using Viht N5 series please?

 

I use N570 for 338 LM, N560 in 260 rem for the 139g scenars and N550 for the 123g Scenars in 260 rem.

 

I use these simply because they work for me rather than a quest for ultimate speed.

 

The barrel / throat wear issue is repeatedly mentioned despite Vihts claim to the contrary.

 

Is there a reasonable and experienced based ratio of faster wear vs the single powder equivalents...IE what (approx.) are the N5 series costing me in reduced barrel life ?

 

I am not opposed to changing my loads but it would be massive 'faff' especially if the extra wear is nominal.

 

Cheers

 

Dave Thain

[Grouse]

Laurie

 

Can you help me with the issue of reputed accelerated barrel wear using Viht N5 series please?

 

I use N570 for 338 LM, N560 in 260 rem for the 139g scenars and N550 for the 123g Scenars in 260 rem.

 

I use these simply because they work for me rather than a quest for ultimate speed.

 

The barrel / throat wear issue is repeatedly mentioned despite Vihts claim to the contrary.

 

Is there a reasonable and experienced based ratio of faster wear vs the single powder equivalents...IE what (approx.) are the N5 series costing me in reduced barrel life ?

 

I am not opposed to changing my loads but it would be massive 'faff' especially if the extra wear is nominal.

 

Cheers

 

Dave Thain

I too would like to know about the wear on throats with N500 range of powders.

 

DaveT suggested I use N550 in my 260rem, it's transformed it, compared to H4350 - in regards to accuracy, lack of carbon in barrel and good velocity levels.

 

Enjoyed this thread immensely, I went with 260rem over 6.5x47 due to effortless repeating in hunting situations if needs must. The use of an AI magazine enables longer COL, which was important for me as my rifle was built by Baldie and his reamer throated for 140gr bullets.

[Elwood]

Laurie, Google 6.5 Saum. I'm told that 3100 fps is easily achievable with a 26 inch barrel and 140 grain projectiles.

 

I will let you know in the near future if it's possible