260 velocities - bit slower than expected

[dashed]

Had a Sako 75 rebarrelled from 243 to 260 (21" pacnor) and struggled to find a load that shot less than an inch. Worked my way through various powders (H414, H4350, R17), different jumps, different primers, bullets etc and finally found it liked Vhit N160 where it will put 3 through the same hole if I do my but. However, I had the opportunity to chrono the loads this week and surprised (disappointed!?) at the results as I was expecting to be in the 2,750 to 2,900 range. Bullets are Nosler 120gn BT and Nosler 130gn Accubonds:

 

42.3gn N160, 120gn BTs - 2611 , 2588, 2641 - average 2,613fps
40.8gn N160, 130gn Accubond - 2555, 2536, 2532 - average 2,541fps

 

They are definitely the sweet spots for powder weights as if I go below / above that then groups open up quickly.

 

Am I chasing unnecessary velocity at the expense of accuracy??

[John MH]

If it shoots tight groups and accuracy is more important than velocity stick with the bug hole combination. I use N160 in my .260 with 139 grain Sceanars, it shoots nice tight groups but is no way 'hot' and doesn't need to be.

[gbal]

Had a Sako 75 rebarrelled from 243 to 260 (21" pacnor) and struggled to find a load that shot less than an inch. Worked my way through various powders (H414, H4350, R17), different jumps, different primers, bullets etc and finally found it liked Vhit N160 where it will put 3 through the same hole if I do my but. However, I had the opportunity to chrono the loads this week and surprised (disappointed!?) at the results as I was expecting to be in the 2,750 to 2,900 range. Bullets are Nosler 120gn BT and Nosler 130gn Accubonds:

 

42.3gn N160, 120gn BTs - 2611 , 2588, 2641 - average 2,613fps40.8gn N160, 130gn Accubond - 2555, 2536, 2532 - average 2,541fps

 

They are definitely the sweet spots for powder weights as if I go below / above that then groups open up quickly.

 

Am I chasing unnecessary velocity at the expense of accuracy??

 

Yes.

 

You could check on another chrono; when would another 200+ fps/130 ft lb energy matter in UK?

 

gbal

[The Gun Pimp]

Yes.

 

You could check on another chrono; when would another 200+ fps/130 ft lb energy matter in UK?

 

gbal

 

Always!!

 

Seriously though - I thought the 260 would be way better than the 6.5x47 in terms of velocity - but 'dashed' has discovered what lots of others already have.

[jcampbellsmith]

I shot the following loads in a 260 Rem that's throated long with a 23.5 inch barrel so it's unlikely these loads will work in your rifle. I do however like N160 for this weight of bullets. I'm not trying to achieve 'hot' loads.

 

Manufacturer Bullet BC Powder Weight Brass Firing Chronograph Average

Hornady 123 Amax 0.510 N160 44.85 Nosler 8 Magneto Speed 2887

Hornady 123 Amax 0.510 N160 44.85 Nosler 1 Magneto Speed 2858

Hornady 129 SP 0.445 N160 44.30 Lapua 3 Magneto Speed 2797

 

As above I would suggest trying another chrono. I wasted a lot of time before I got the Magneto Speed.

 

When I had a Sako 75 in 243, I did contemplate making the same move as you have made.

 

Regards

 

JCS

[tackb]

you could try N560 ? I use it under 140 amax for 2800fps although it's suddenly stopped grouping so well and at the moment I'm blaming me and lack of practice recently ?

[jcampbellsmith]

You don't say what type of brass you are using? Regards JCS

[gbal]

The original "6.5 shootout" comparison reported 260 139@2820,and 6.5 Lwas down on this,though comparisons are slightly skewed becauae the 6.5 tends to use 123 bullets.

As the author said,however, experienced 6.5L reloaders with the strong bras and strong custom action cam close the gap.Quite so.

But then,the 260 reloader might also improve velocities-and the author reports AW 260 139 scenar rel17 2900,with some friends going to 2980.......

 

I'd have thought that's about enough and then some for any of the trio....OTT,and goodness knows what pressures......this was in 2009-maybe it's gone more sensible since.

 

Vince,the more general point about max velocity-well,it does no harm,always provided accuracy is maintained...but the post said clearly that more powder led to 1 inch plus groups.....not too good...

one important issue is what kind of shooting-my point was that another 100ft lb is unlikely to be critical in field shooting (UK deer),and a very iffy trade off against 2 inches off POA,though tolerable.

For varminting,accuracy really is paramount (given reasonable ballistics). In the field,the 3 inch wide crow has to be actually hit,not impressed to death by a tiny group of shots just missing.And at 300y,three inches isn't offering much leeway,hence the premium on accuracy-anywhere on paper won't do-it has to be (almost) anywhere on crow!

Of course,a bit extra velocity for long range target shooting is always useful-proviso,no accuracy loss.

If we can find a "Dasher plus" for 1000 running,fine (accuracy point maintained.

Though there is still a certain plausible credibility in the Texas Tunnel Man "Didn't measure velocity-if it goes through exactly the same hole,it does not matter how fast".

 

There may be a transactional relationship too,and velocity /accuracy are not completely independent-but 'nodes' clearly show there is no simple linear relationship either....once we are into wind,it changes again,with the exact trade offs not really calculable(but 3" intrinsic rifle precision isn't a good start).

 

But our cunning plan was to avoid wind changes.... :-)

 

g

[dashed]

Thanks all for your thoughts - I'll stop worrying and try and find another chrono!

 

Lap brass.

 

Edit: Just done a bit of research into the chrono I was using (not mine) and it appears the type I used needs to be dead level and perfectly aligned to give the accurate results (and not just slapped on the bench a few feet in front of the muzzle!!!). Maybe I'm not as slow as I think I am??!! http://www.steinertsensingsystems.com/product/superchrono-std/

[Hatzi]

Did anyone else read the point about a 21" barrel?

[Laurie]

These are mild loads and with 21 inches I'm almost surprised you're getting that much velocity. (Yes, I know what Lapua shows as maximum loads and as usual with this company they are very, very cautious.) N160 isn't tne best choice for the cartridge, presumably why few bullet company manuals including Nosler's include loads for it.

 

Try to find the next sweet spot up the pressure curve. Groups are usually replicated in this size of cartridge at around 1.4-2gn intervals.

[gbal]

Noted,Chris - velocities still seemed 'reasonable' -the hot US loads were 200+ higher,allowed about 100fps for short barrel-very ball park-and suggested it's not bad,and accuracy matters more,as other loads lost it....and in general,I don't see that revving in the red zone is something desirable,to put it politely.But point taken-short barrel means some loss of velocity,necessarily-though neither are deal breakers,I'd rather drop 100fps and pick up 1/4 inch accuracy-no contest in a target rig,hunting-how big is the quarry? :-)

[Swarovski1]

Hi George.i cant see a 260 launching a 139gr scenars at 2820 to 2900fps.2750 maybe that will trash the cases.a mate had one and he found the 139gr scenar most happy at 2600fps

[Georgek80]

I have a 260 at 18 inch barrel 41.5 gr h4350 140 a max at 2517 and 42 gr h4350 with 120 nosler bt at 2717 my 260 before that was barrelled at 22 inch I have lost around 160 fps I kill a lot of deer no difference with loss of vel and still shoot out at long distance at targets and gongs very well

[Hatzi]

Hi George.i cant see a 260 launching a 139gr scenars at 2820 to 2900fps.2750 maybe that will trash the cases.a mate had one and he found the 139gr scenar most happy at 2600fps

2820fps with 139's and 43.4gr H4350 is what mine has been doing for 5 years with Lapua 260 brass. It would happily go over 3000 with Re17 back in the day but its minging dirty inconsistent powder. Cases have done maybe 10 firings? 26" barrel.

[gbal]

Hi George.i cant see a 260 launching a 139gr scenars at 2820 to 2900fps.2750 maybe that will trash the cases.a mate had one and he found the 139gr scenar most happy at 2600fps

Swaro,I would not be doing it,lightly.The data is from Accurate Shooter,which tends to max/hot loads-thou says so-often from competition shooters looking for all they can get...and remember,these are in 'strong ' custom actions,which probably do give a bit more confidence. The cases-well,there usually isn't data on number of firings.

As you can read,my view was that if accuracy is better,what does a hundred or more fps cost you? I prefer wimp apology loads to macho bragging loads,given the ammo performs.I've read Litz,as well as Freud and evo-biology,and two are wrong.

My compliments to your 2600 fps mate,even though commercial 140 loads run about 2750+/- 50 (24 inch barrel,Nosler,Federal,Remington.) :-)

g

[John MH]

N160 isn't the best choice for the cartridge, presumably why few bullet company manuals including Nosler's include loads for it.

 

 

That's not my experience.

[maximus otter]

I shoot Lapua 139 grain Scenars in my Valkyrie .260. I use the maximum load in the Vihtavuori manual: 43.4 grains of N160.

 

Out of my Border barrel (28"?) 15 rounds gave me an average velocity of 2787 and an SD of 12.9. Velocity measured with a Magnetospeed. Bullets seated 10 thou off the lands.

 

http://www.vihtavuori.com/en/reloading-data/rifle-reloading/-260-remington.html

 

maximus otter

[Swarovski1]

With a 28 inch barrel the velocities are more achievable, mates 260 had a armalon barrel on it, its Identical to my 6.5 06 barrel inc twist,obviously not the chamber, I am still hung up on my recent discovery on my loads up to 100fps down, some loads were using hodgdon extreme powders,not sure the colder weather would reduce fps that much,if a 260 goes that fast I would of had one instead of a 6.5 06

[gbal]

With a 28 inch barrel the velocities are more achievable, mates 260 had a armalon barrel on it, its Identical to my 6.5 06 barrel inc twist,obviously not the chamber, I am still hung up on my recent discovery on my loads up to 100fps down, some loads were using hodgdon extreme powders,not sure the colder weather would reduce fps that much,if a 260 goes that fast I would of had one instead of a 6.5 06

Rifles and barrels vary a bit,as do powders etc etc.The 6.5 -06 should have a slight edge in capacity,but efficiency is another matter.

What do you think another 100fps would offer in the real world,even assuming equal accuracy etc? How do you know the velocity was accurately measured in both rifles-there is a fair amount of evidence here for chronic chronos! I suppose a side by side comparison of both rifles at the same time might be fairly reliable comparative data....as said,what though,does 100fps more really offer.....? The 264 Phantom,Winchester magnum and 6.5 Rem mag will all 'on paper' give a hundred or so more fps,anyhow....and the latter two did so fifty years ago...maybe more with improved modern powders...Nosler 260...at some point ,the relevant question is "To what purpose?"

g

[Laurie]

 

That's not my experience.

 

 

Depends on how you define 'suited' John, and what you're looking for. I've used N160 in this and similar cartridges in the past and when I returned to 260 two or three years back and started looking up loads, I was soon struck by how few entries it has in recently published manuals. Only Speer and Lyman quote loads, both for a single bullet model/weight, and both listed as 'compressed loads', the Lyman entry with a low MV, this explained by the pressure column showing 50,000 psi for the maximum charge weight compared to a SAAMI MAP of 60,190 psi. This is not down to ignoring Vihtavuori powders, as many manuals quote one or more Viht loads for each and every bullet weight in the cartridge, the majority being N150, a slightly smaller number N550, and far fewer N140 and N165 applications.

 

This made me wonder a bit as manual compilers have to prioritise what they use out of the many suitable powders that they'll try for a cartridge model / bullet weight. They look for something that will likely group well, but is also efficient in the combination, ie produce maximum allowed pressure allied to good velocities and at the very least reasonable velocity spreads.

 

Stick the powder into QuickLOAD and you get the same results as Speer and Lyman with most combinations - compressed loads before allowed peak pressures are achieved. So-so MVs result, but also poor percentage charge burn figures and hence poor thermal efficiency values. This is partly because QuickLOAD's default case capacity is very low at 53.5gn whilst my current 260's chamber and Lapua brass increase that to 55.1gn. Run Lapua's max N160 charge of 40.6gn through it with the 139gn Scenar and 2.850" COAL that my rifle's throat allows and you get a near full case, under 40,000 psi PMax, 2,555 fps from a 30-inch barrel and just under 93% charge burn in that scenario. While I say that my brass is more capacious than QuickLOAD's, it may be that when the American manual compilers tried their loads, their brass was heavier with less internal space more in line with the program's default.

 

Changing things to my rifle + brass actual capacity and ignoring entirely what the Viht manual says, going up to a charge weight in QuickLOAD computed to use 105% of available case capacity improves things with an estimated 2,797 fps from the 30-inch barrel, but it's still only running at 52,650 psi (computed) from a fairly stiffly compressed load and the charge burn has risen to 97%, better but still lower than I'd like in any load I choose.

 

Of course, QuickLOAD may be producing total garbage, but I do have some real life results to put up against the model. I had a long-action rifle rebarrelled to 6.5 by Norman Clark some years back with a 30-inch Krieger and it was a toss-up between 6.5X55 or 260 throated really long to use 140s at a shade under three-inch COAL. I thought the latter would be 'interesting', but in hindsight I now wish I'd gone for 6.5X55, a much better choice for the action. There was no Lapua 260 brass back then, so it was matter of expanding its 243, easy to do but it produces horrendous 'doughnuts', still no problem in this rifle as the bullets were seated so far out the pressure ring sat above the offending item. Having used N160 for years in 6.5X55 and 7X57, I 'knew' it would be the powder and set about working loads up with it and factory moly coated 139gn Silver Scenars. Even with the 3-inch length, MVs were disappointing unless the cartridge was really stoked up, and I did get it up to 2,880 fps eventually but that took it past a charge compression level I was happy with. (Incidentally, before people faint with fright at likely charges, modelling that combination in QuickLOAD says it was only producing 56,000 psi - remember an extra 0.2 inches less bullet seating, and moly coating reduces pressures a lot.) Groups weren't brilliant up there, in fact groups weren't that brilliant anywhere, but like the OP I eventually seemed to find one that just hit the ticket, five shots in quarter inch at 100. Velocity ES /SD looked good too at 15 / 6 and I thought I'd hit the jackpot even if the MV was less than I'd wanted at 2,797 fps. Still 2,800-2,850 is what everybody says 140gn class 6.5s perform at and I was nearly in it, maybe the barrel would gain a bit of extra speed as it became fully run in.

 

In practice, this load was entirely inconsistent subsequently in competition. Some times it seemed OK, occasionally brilliant, but more often it was BAD and I couldn't see why. Running it through QuickLOAD now, I think I can - 50,400 psi the computing machine says, too low to work consistently and efficiently. The other charge weight results in the test strings should have told me something - groups larger than the half-inch throughout and ES values that ran at 60 fps plus. Anyway, the rifle was eventually put on one side and is now another 6.5, and I have another short-action, shorter throated 260 in its stead that shoots 123s brilliantly at a little under 3,000 fps with N150 (also 30-inch barrel), but I still had the best part of a box of the moly 139 3-inch load in the reformed 243 brass sitting in the ammunition cabinet. So after looking at QuicklOAD again, it looked safe at a bit over 2.8 inch COAL to suit the new chamber and the bullets were reseated a lot deeper. Like a LOT deeper and this load was now really compressed to the point of feeling and hearing kernels crunching under the bullet, too much pressure needed on the press and rings left by the seater stem on bullet noses, problems getting the COAL down enough and remaining consistent. This started to worry me more than a little bit, like what sort of pressure would this naff load actually produce, and maybe I'd better pull them to be on the safe side. Still QuickLOAD predicted under 56,000 psi and around 2,850 fps and the bullets were moly'd, so I gave it a go with some trepidation - needn't have bothered, no pressure signs at all! Groups were sh+t, but you can't have everything. I didn't chronograph the results - wish I had as it would be interesting to see what a silly charge of N160 produces.

 

I reckon that N160 is just a bit too bulky, too slow burning for the 260's case size. With limited case capacity too, you want a fairly energetic powder and N160 is modest at 3,620 KJ energy per Kg weight, one of the lowest handloading powders around - IMR and H. 4831 are 100 and 200 higher and VarGet popular with a lot of 260 shooters is rated at 4,060 KJ / Kg, Alliant Re19 which Nosler itself (to return to the OP's bullets) quotes for all four bullets from 120 to 140gn and gives its 'most accurate poowder' accolade to the 125 and 130gn loads is ~4,000 KJ / Kg and being a nitroglycerine infused high-energy type is also considerably denser than Viht N100 series powders matching case capacity better.

 

However, I suspect that Reload Swiss is going to provide the in-powder for the smaller 6.5s, single-base and relatively cool burning RS62 that is. On paper anyway it ticks all the boxes for 6.5 Creedmoor and 260 Rem with 140s and I'll try it shortly in both.

 

When it comes to 260 MVs in shortish barrels, here's an old one from Accurate Shooter's 6mmBR.com days - Terry Cross's US Sniper Championship winning 260 'Improved' with 2,950 fps from 139gn Scenars out of a 26-inch barrel.

 

http://www.accurateshooter.com/guns-of-week/gunweek046/

[bradders]

When I was using a .260, my load was 42gn N160 and a 142MK

Velocities were just under 2800 IIRC, and that was with a 30" Gary Schneider barrel.

 

It shot like a dream though

[John MH]

Well I am nowhere near compressing loads with the 42.5 grns of N160 I'm using in Lapua Cases and with 139 Scenars and seated below maximum length to fit in an AICS .308 Mag. Velocity has not been measured recently but its a tad over 2700 fps and shoots really well.

[Swarovski1]

If my 6.5 06 velocities dont go up in warmer weather then it is under performing, my current fastest load is a 140 vld doing 2770, I and reluctant to change ttem at the mo just incase the fps returns

[Laurie]

Well I am nowhere near compressing loads with the 42.5 grns of N160 I'm using in Lapua Cases and with 139 Scenars and seated below maximum length to fit in an AICS .308 Mag. Velocity has not been measured recently but its a tad over 2700 fps and shoots really well.

 

 

As long as it works well for your particular shooting, I'm not going to argue. It'll be a low-pressure load and with N160 a 'cool burner', barrel wear and tear will be very low - never a bad thing in a 6.5. I tend to look at things through the lens of 1,000 yard F-Class, or for that matter 500/600 yard F-Class. In either case there is little leeway for underperforming cartridges, especially when they start out as relatively (compared to the 7mm Shehane and larger) small numbers.

 

The point I'm trying to make is that the 260 is capable of very much higher MVs than many people realise and that there are a lot more powder options out there these days to get a close match that optimises performance if that's what's needed. The strange thing is that of the two 6.5 'rivals' out there which generate very large numbers of words on UKV, some people are quoting loads and claiming performance for 6.5X47L that frequently frighten me, whilst 260 often seems to be the other way round.

 

To go back to the OP's point and gbal's response, if it works it works and MVs are irrelevant, as long as they're high enough to produce reliable expansion on live game in his case.