260,260ack or creedmoor

[Laurie]

There is no single-base to high-energy conversion factor that I'm aware of, and powder energy is only one of several factors - speed of shooting and resulting barrel throat temperature might play a larger part in this than powder, and of course the peak pressure produced plays a part.

 

What there is that might help is a spreadsheet that calculates barrel life and which has the specific energy levels for all the common powders held in the information part of the appropriate cell. See:

 

http://bulletin.accurateshooter.com/2012/07/handy-excel-formula-predicts-useful-barrel-life/

 

Using QuickLOAD with .260 Rem + the 139gn Scenar at 2.900-inch COAL to get an indication of powder charge weights allied to pressures produced by three Viht powders, here is what it predicts

 

40.8gn N150 / heat value 3,780 / 60,196 psi = 2,464 round barrel life

42.9gn N550 / heat value 4,050 / 60,000 psi = 1,583 rounds barrel life

46.6gn N560 / heat value 4,020 / 54,183 psi = 1,542 rounds barrel life

 

All these are on the slowest shooting rate setting. A rapid fire discipline would reduce them.

 

I'm surprised that the N560 load life estimate is so relatively low in that according to QuickLOAD even a compressed (105% fill-ratio) charge fails to get up to the 60,000 psi level only achieving an estimated 54,183 psi.

 

I've no idea how accurate this spreadsheet is in its predictions, but comments on AccurateShooter have suggested that real life barrel lives and the predisctions are not too far out.

 

If so, using Viht N500 series powders doesn't appear to be great idea!

[The Gun Pimp]

Don't want to hi-jack Laurie's input but I do have some first-hand experience.

 

I used Vit N540 in my 308 FTR rifle and the barrel went in the scrap-bin at a little over 1000 rounds. I was quite shocked at what the borescope revealed.

 

Another keen FTR shooter, who isn't given to reckless expenditure (he's from Yorkshire) had the same experience - he noticed a fall-off in accuracy close to 1000 rounds, kept it going for another 200, then bore-scoped it and binned it.

 

Bear in mind, mine was still shooting well under one MOA but, when new, it was sub half MOA.

[Elwood]

http://forum.snipershide.com/snipers-hide-bolt-action-rifles/185807-new-gap-extreme-hunter-6-5-saum.html

 

This might be hijacking the thread, but I thought while we're talking 6.5's this might be of interest, only 27 pages to digest

[Laurie]

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

 

Ian,

 

I believe you - so does QuickLOAD as it shows no fewer than 28 powders that are available in the UK (when they're in stock anyway!) that will achieve this feat with a 139gn Scenar. That includes H. VarGet, but only just at exactly 3,000 fps depsite this being a far too fast-burning powder for the cartridge you'd think!

 

There is a single reason for this - the SAUM (and WSM too) are rated at 65,000 psi max pressure. If you can run at that sort of level you gain a good chunk of extra performance.

 

Just for fun (Hee! Hee!), I assume you'll use your 6.5SAUM in CSR and manage to get a shot off every 5 seconds. The 'Accurate Barrel Life Predictor' says you'll get 85 shots' worth of fun from your 6.5mm cannon with nearly 60gn of Viht N560 and 65,000 psi for a bit short of 3,200 fps MV.

 

Before you panic too much, that rises to 778 if you shoot slow. So, just don't use it in a lot of McQueens comps or suchlike.

[dannywayoflife]

What's people's views on tuftriding to poling barrel life?

[Elwood]

Ian,

 

I believe you - so does QuickLOAD as it shows no fewer than 28 powders that are available in the UK (when they're in stock anyway!) that will achieve this feat with a 139gn Scenar. That includes H. VarGet, but only just at exactly 3,000 fps depsite this being a far too fast-burning powder for the cartridge you'd think!

 

There is a single reason for this - the SAUM (and WSM too) are rated at 65,000 psi max pressure. If you can run at that sort of level you gain a good chunk of extra performance.

 

Just for fun (Hee! Hee!), I assume you'll use your 6.5SAUM in CSR and manage to get a shot off every 5 seconds. The 'Accurate Barrel Life Predictor' says you'll get 85 shots' worth of fun from your 6.5mm cannon with nearly 60gn of Viht N560 and 65,000 psi for a bit short of 3,200 fps MV.

 

Before you panic too much, that rises to 778 if you shoot slow. So, just don't use it in a lot of McQueens comps or suchlike.

Laurie,, what barrel life does it predict at 55,000 psi and 58,000 psi ?

[gbal]

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

Way back in 1958,the 264 Win Mag was in the ball park with factory 140 loading at 3030fps;and Rem and WIn currently still do that. Noslers 140 g Partition loading with better BC(.49) comes in at 2950. 24 inch barrel,1 in 9,64000 psi SAAMi giving 3015fps.

 

Of course it's an old codger now,but it can burn barrels just like these new whippersnappers.

Gbal

[Laurie]

Laurie,, what barrel life does it predict at 55,000 psi and 58,000 psi ?

 

 

Ian

 

It depends on the powder as you have a fair choice and there is a 100 fps + variance on predicted MVs. But I've assumed you'd look for something close to 3,000 fps and from a single-base powder. As with Swarovski's 6.5-06, the best bets on QuickLOAD appear to be IMR-7828 and H4831.

 

If you take H4831 at the two pressure levels, you're predicted to get 2,945 fps at 55,000 psi and 2,994 at 58,000 psi. The life predictor says 1,291 and 1,185 rounds slowfire respectively.

 

At 58,000 psi, IMR-7828 should produce around 3,071 fps and this looks the best powder for 6.5SAUM. The predictor says 1,170 rounds life.

 

However, should you fancy N560 which gives the highest predicted MV, but only at 3,079 fps a mere 8 higher than 7828, the predicted barrel life falls to 937 rounds at 58,000 psi.

[Laurie]

As The Gun Pimp (Vince) says, some of us got nasty shocks in the early days of F/TR with hot N500 series powder loads. I think though that there was something very odd indeed in the 1,000 round life with N540 - maybe the barrel steel was 'soft' or something.

 

Around the same time, I was shooting a 30-inch Broughton 1-10" twist. It had a right old mixture of powder makes, grades, loads and pressure levels as I did a lot of testing with it for magazine features. My main match round was the 185gn Berger Juggernaut and enough N550 to get it to 2,825 fps, a 'warm' load. I latterly did a lot of very heavy bullet (208 and 210gn) testing with it with N550 and Reloder 17, but then it'd have an easy time in a short-range match between-times with 155s over N150 at 2,925 fps.

 

It packed up at around 2,200 to 2,300 rounds, completely packed up that is with a chunk of land just ahead of the chamber disappearing, presumably out of the muzzle! In hindsight though, I had abused that barrel in testing by firing over-long strings. I now limit a string to 10 rounds and let the barrel cool completely before the next.

 

In any event, many F/TR shooters switched to H4895 / VarGet with 155s and N150 with 175 to 190s from 2011. Only the heavy-brigade with their 200-230s still use N550. some of them claim good life though.

[Swarovski1]

Wow this thread is getting intresting, I am not 100 percent on this off hand,I made several lots of ammo when it was being rebarreled, most at coal of 3,300 didnt chamber, scenars, smks and bergers did, I know comparator measure is2,710 chambered, the ones I use are 2,680 comp measure and its 29 to 30 fow off,3,310 is approx coal of 142gr smk chambered.

[DaveT]

Hmmmmmm!!!!

 

Many thanks to Laurie and Vince for the feedback.

 

My 260s are both at around the 1000 round mark and fine so far....my shooting does not require extended strings.

 

Given that I am that far along re barrel 'lifespan' I plan to continue with the N500 series (I have a good stock!) and see what happens....BUT I will seriously review which powder to use when it comes to rebarreling time.

 

I wonder what Viht would respond on this issue?

[Swarovski1]

My gunsmith told me when the throat is shot it would cost around £150 to lob off the an inch re-thread and re-ream, shouldnt be much difference one inch shorter hopefully, as it is my hunting rifle thats fine by me, I suppose I could do the same when throat is shot again, a big thanks to laurie from me too, anymore advice and info please let me know.

[DaveT]

My gunsmith told me when the throat is shot it would cost around £150 to lob off the an inch re-thread and re-ream, shouldnt be much difference one inch shorter hopefully, as it is my hunting rifle thats fine by me, I suppose I could do the same when throat is shot again, a big thanks to laurie from me too, anymore advice and info please let me know.

Have wondered if that is a real option myself......if the throat is knackered then there would presumably be a deal of wear in the rest of the rifling as well?

[bradders]

My gunsmith told me when the throat is shot it would cost around £150 to lob off the an inch re-thread and re-ream, shouldnt be much difference one inch shorter hopefully, as it is my hunting rifle thats fine by me, I suppose I could do the same when throat is shot again, a big thanks to laurie from me too, anymore advice and info please let me know.

Yeah, £150 plus proof and postage to and from and you're 1/3 of the way towards a new barrel

[Swarovski1]

I assumed that was all in price not plus this and plus that.wouldnt do postage just collect on a range day.

[Swarovski1]

Hi laurie, could you post some ql loads for 260 rem,26 inch 1 in 7.89 twist, ai mag length is 2,900 so cartridge would have to be shorter, atb swaro

[baldie]

Its a good job borescopes are so expensive.

 

If all shooters owned one, then there would be far less bullshit talked about lobbing an inch off a barrel and basically fleecing a customer into thinking he has virtually a new barrel again on his gun.

 

If the throat on a barrel is so bad as to even consider a new one , then the 8-12" beyond it will be utter toast too.

 

Throats dont wear by one inch, the entire barrel wears at the same rate, and the front half will be knackered too.

 

A lot of gunsmith friends do it on their own guns etc, and squeeze 2 or 300 more rounds out of a barrel, but its taking money under false pretences to tell a customer that he will get the same barrel life again by doing it.

 

I wont do it, and even if I did, it would cost exactly the same in labour as a new barrel would.

[The Gun Pimp]

Well said Baldie - I occasionally 'top n tail' barrels to freshen 'em up but I don't like to run a reamer into rock-hard badly firecracked barrels.

 

You may as well pay your gunsmith to do the work on a new barrel - the cost/work is the same surely?

[Swarovski1]

Thats what I like, strait talking, I read on the net somewhere about taking inch off, if barrel is fekked all through then so be it, thanks for that baldie, like it, say it as it is, thats how I am, atb swaro

[The Gun Pimp]

This has been an interesting discussion on the 260Rem., 6.5x47 and the 6.5 Creedmoor. Laurie already has the first two (he has the Creedmoor as well but built on an AR) and before long, he will have the third.

 

Laurie - this would make a great 'head to head' test for Target Shooter if you are up for it.

[Laurie]

Oh yes, there will definitely be a group report next year with a bit of 6.5X55mm thrown in for good measure. I also plan a head to head report on the more common sevens at a later time - 7mm-08 Rem, 7X57mm, and .284 Win.

 

PS seeing as how Foxing-2-Nite (Darren Evans) has humbled us all again in yesterday's 600yd BR match doing simply unbelievable things with his 6.5X47L Accuracy International and 130s, I'm tempted to bring my .260 Rem FN and its 123gn Scenar load along to the next one on the 29th to see how they cope with the Diggle wind. I don't think I can swing it as a 'factory sporter' though with the Tiger Tank cannon profile Bartlein barrel up front and Jewell trigger !!

[Swarovski1]

Still surfing the net looking at the 6.5s, found one artical someone using a the creedmoor 21.5 inch barrel with factory hornaday 140gr amax ammo so say doing 2795fps, has anybody used this stuff and put frew the chrony or is this total horse shite, none of reloading data ive looked at comes near these velocities.

[Laurie]

Hornady lists its factory ammo as 2,710 fps from a 24-inch barrel, and factories only rarely err on the slow side, so an extra 85 fps from a 2.5-inch shorter barrel seems unlkely. Some people have optimistic chronographs allied to active imaginations!

 

Hodgdon's highest handload MVs with a 140 gn class bullet are 2,736 with the A-Max and 2,737 with the 142gn Sierra MK also both from a 24-inch barrel. However, these results are from Hybrid 100V, a modified double-base ball type powder. The highest MVs from a single-base powder are 2,664 / 2,694 for these bullets respectively, both with H4350. Since this is the powder that Hornady loads its factory match ammo with, that's in line with the factory claims, in fact makes the factory figure look good for the A-Max.

 

The 6.5mm Creedmoor is limited by the amount of powder and hence energy you can stuff into the case. This applies a bit more so to the .260 Rem if it's kept to the 2.800-inch COAL with 140s, and even more so to the smaller cased 6.5X47mm Lapua. Hodgdon's 140gn H4350 A-Max maximum load is shown as compressed with this bullet. It takes a case-full load of double-base or high-energy powders to obtain a significant MV increase over 2,700 fps for 140s in this trio with the 24-inch barrel length.

 

Just out of interest I used an ME calculator facility to see what the equivalent MVs are with 139-142gn bullets to the nearly 3,000 fps MV that my pet .260 Rem 123gn Scenar load produces. (That's with Viht N150 in a 30-inch barrel). The equivalents are 2,790-2,810 fps depending on bullet weight to produce the same number of ft/lbs ME. ~2,800 fps is in line with the MVs many people use in the trio in 28-inch plus barrels in F-Class and similar. Higher MVs can be obtained with N550 and its equivalents, but at a barrel life cost.

[Swarovski1]

Thanks again laurie, I seem to get the feeling to go the creedmoor way,defo between that and the 260, so say the creedmoor is what the 260 should of been.its mainly going to be a range rifle, no doubt it will go across the fields occasionally as does my 308.decisions decisions decisions.

[Grouse]

I went with 260, and used with an AI box magazine can seat heavy bullets out long to the lands - this in my opinion makes it a better option than the Creedmoor, especially with the available brass for the 260.