260 rem 123gn ELD-Match & N560 1:8 twist

[Mick Miller]

Advice from 260 rem shooters please. I have amassed the following data on my chosen bullet (by weight). Out of this lot (I'm only interested in using VV as it's available everywhere, just about) N160 seems a popular choice but Nosler throws up N560 as an option. Now in my experience Nosler's data is usually close to real world, same as Sierra's, certainly when developing my 243 and 222 loads it was a good benchmark to work from. N560 sits between N160 & N165 and is meant for magnum type cartridges so that explains the better velocities. I'm interested in better velocities as I'll be using the 260 for some long range target work too.

Any thoughts on using N560 only? things to watch out for (is it quick to go from mild to wild?).


 

[DaveT]

N550 would be better than N560 for 123g ...N560 is great for 140g class

[DaveT]

Cannot see any reference to barrel length re powder burn efficiency and resultant MV.

[Mick Miller]

Tikka T3X Super Varmint barrel length 23 3/4". N550 seems to be the same ballpark as N160 velocity wise.

I have a almost full tub of N150 here. I might just start with that and see what velocities I get.

 

 

[Matt234]

Hi

I have two 260 rem's they both like N165 with 129SST 125 nosler bullet's best to start at minimum load and a chrono is a must N150 works well with the 100 gr AMax that's my fox load.

[Mick Miller]

Thanks Matt, I'm going to try the N150 first, I have that here and Laurie posted some info about using it with a 123gn Scenar, add long as I work up slowly and don't exceed 40.5gn or should be okay. 

Is good to have alternatives and some folk state they've had success with N140 even. I have some of that too as it's my go to fit the 243. 

As I want a load that will still hold a group out to 800-1000 yards MV is the key (as long as it groups). As always it's a trade-off between the two. 

[Laurie]

With hindsight, 40.5gn is VERY hot in the 260, so I'd say don't go there, but N150 will likely give good results around the 39gn mark.

The 123gn Scenar is a competent 1,000 yard bullet and the benefits of shooting most 139-142gn bullets over it are actually pretty small when you run the numbers in the 6.5s up to and including 6.5X55mm..

[DaveT]

If it helps and with the usual workup caveats I am VERY happy with 123g Scenar or 123g SMK over 41.5g - 42.0g of N550.

When I go to 139g Scenar or  140g Berger Hybrid (loaded long) I use 44.5g N560 and 46g N560 respectively.

As Laurie notes the 123g is fine at 1000yds....Not sure it wouldn't happily compete beyond that but I step up a weight class for longer shots.

[Mick Miller]

DaveT & Laurie, noted. I'll try the 150 first then if that fails to produce the goods I'll move over to 550. I'm unlikely to use anything other than 123gn for a while.

[Matt234]

I'd used the N165 with the 129 SST out to 800 meters at orion's range no problems hitting the sniper target every shot once I got on target with the rifle Steve Kershaw put together for me my factory sako was nearly as accurate but not quite.

[No i deer]

Laurie you say they'e is nothing innit between the 123gr and 139gr scenars.i just checked my balcal with the 123gr and 140gr amaxs and there is a 6 inch more drift with the 123's in a 9mph wind.thats quite a bit.are you thinking the 123 keep there verticals better.cheers no I deer

[Laurie]

1 minute ago, No i deer said:

Laurie you say they'e is nothing innit between the 123gr and 139gr scenars.i just checked my balcal with the 123gr and 140gr amaxs and there is a 6 inch more drift with the 123's.

 

On what basis? ie At what MVs?

[No i deer]

2850fps with 140gr amaxs

3000fps with 123gr amaxs

[Mick Miller]

TBH I read exactly the same, the 123's were, on paper, more wind affected. Still, if you're compensating then compensating another 6" isn't really a big deal, or is it? I have zero experience shooting long range I admit, but if you're dialing or holding to compensate, at 100 yards, 6 inches is faff all it seems to me.

 

[No i deer]

I'm talking 1000yds.

Yes 6 inches is a lot really.yes you still have to compensate for it but the higher BC bullet should be that bit more forgiving. Personally ive found very little to nothing between shooting a 308 and 6.5x47 out to 1000yds.that probaby tells you alot about my shooting.i don' use a rear bag though.fingers usually.recently a monopod in a clenched fist but I can say I am not a lover of them.the very last time I folded it away and sat it in palm of my hand

[Laurie]

4 hours ago, No i deer said:

2850fps with 140gr amaxs

3000fps with 123gr amaxs

 

3,000 fps with a 123 isn't directly comparable to a 140 at 2,850 as it handicaps the lighter bullet. The usual way to obtain comparable MVs is to use ME. The 140 at 2,850 fps produces 2,525 ft/lb ME; the 123 at 3,000 = 2,458 ft/lb. It takes 3,040 fps to get up to an equivalent value, and that's the MV that should be input for the lighter bullet.

Then there is the issue of 'form factor', the measure of aerodynamic efficiency and in an exercise like this, it's important to compare bullets with similar ratings. Otherwise you end up comparing something like a modern design such as the 130gn Berger Hybrid against the old 140gn high-drag Sierra MK. (When I say that, I'm not talking about bullet v bullet comparisons where their individual designs are a major factor in which is ballistically superior, but when trying to do a comparison showing how much difference bullet weight makes on its own, all other factors pretty well equal.) 

I don't have the form factor for the 123gn AMax so can't see how it compares against its 140gn sibling. But to compare two bullets with similar efficiency ratings we have the 123gn SMK and 142gn SMK whose form factor values are 0.970 and 0.968 respectively, so close as to be within the measuring system's tolerances. Given their different weights / sectional densities, the G7 BC values are 123: 0.260 and 142: 0.301.

Sticking to your 2,850 fps for the heavier model, the equivalent MV for the 123gn version here is 3,061 fps producing 2,559 ft/lb ME.

Stick them into the program and you get at 1,000 yards in the standard 10mph 90-deg wind scenario;

123gn SMK @ 3,061 fps ............... 77.1 inches

142gn SMK @ 2,850 fps ............... 70.7 inches

So, just over six inches difference ......... but at 10 mph. How important this is depends on the application. For traditional prone shooting at paper with sighting shots, one should be close to the target centre on the first score shot and all that matters after that is wind change between successive shots. There are a few southern US desert ranges that I'm told see 10 mph true crosswind speed changes, but I'm glad I don't shoot on them! Bearing in mind wind angles and actual changes and speeds on most days, the amount of shot to shot change is way smaller than 10 mph, more commonly in the 1 or 2mph crosswind equivalent change. So, if you misread an actual wind change by the equivalent of 1 mph crosswind equivalent- and top F-Class and TR shooters read changes much more accurately than that - they have to in order to obtain the scores we're seeing these days - then it is a bullet movement of 7.1 inches against 7.7 inches or just over a half-inch between the pair.

Over the course of a 20-round match that will likely change the score by a single point for an average shooter if everything else is equal. However, using different weight bullets may not see see everything else equal. It's not a given, but frequently a lighter, faster load is easier to shoot consistently over a lot of shots than a heavier, slower one.

However, in the real world it is about actual form factor / BC values of individual bullets. The 123gn Scenar is a very efficient bullet for its weight and has a lower form factor (ie lower drag) value than others in this bullet weight bracket (better than that of most older 140s too) which increases its BC a little over the same weight SMK. So, taking its actual BC as opposed to the higher drag 123gn SMK, its 1,000 yard drift at 3,061 fps is 75 inches or 7.5 per 1 mph change. Unlike the longer / pointier higher BC VLDs it is an easy bullet to tune for precision. It also has another big plus in that it is a LOT cheaper now than its competitors from Berger and Hornady at under £40 / 100, cheaper even than Sierras too now, albeit by not as much of a saving. 

 

[No i deer]

Once the 700 odd 139gr scenars have been used up I will try the 123 grainers.

I doubt that my 27 inch 6.5x47 will get to 3061fps though.n540 can push em at warp speed but I had pressure signs at vihts max load data.i can' remember chronying them but I imagine they were in excess of 3000fps.ive always opted for the heavier higher bc bullets for target shooting.ive got about 50x 123gr amaxs left but no varget.am sure I've got another powder suitable to use them up on.

[Cienfuegos]

11 hours ago, Laurie said:

 

3.000 fps con un 123 no es directamente comparable a un 140 en 2.850, ya que obstaculiza la bala más ligera. La forma habitual de obtener MVs comparables es usar ME. El 140 a 2.850 fps produce 2.525 ft / lb ME; el 123 a 3,000 = 2,458 pies / lb. Se necesitan 3,040 fps para obtener un valor equivalente, y ese es el MV que se debe ingresar para la bala más clara.

Luego está la cuestión del "factor de forma", la medida de la eficiencia aerodinámica, y en un ejercicio como este, es importante comparar viñetas con clasificaciones similares. De lo contrario, terminas comparando algo así como un diseño moderno como el 130gn Berger Hybrid contra el viejo 140gn de alto arrastre Sierra MK. (Cuando digo eso, no estoy hablando de las comparaciones bullet v bullet, donde sus diseños individuales son un factor importante en el que es balísticamente superior, pero cuando se trata de hacer una comparación que muestra la diferencia que hace el peso de bala por sí solo, todos los demás factores bastante bien iguales). 

No tengo el factor de forma para el 123gn AMax así que no puedo ver cómo se compara con su hermano 140gn. Pero para comparar dos balas con clasificaciones de eficiencia similares, tenemos 123gn SMK y 142gn SMK cuyos valores de factor de forma son 0.970 y 0.968 respectivamente, tan cerca como para estar dentro de las tolerancias del sistema de medición. Dados sus diferentes pesos / densidades seccionales, los valores de G7 BC son 123: 0.260 y 142: 0.301.

Cumpliendo con sus 2.850 fps para el modelo más pesado, el MV equivalente para la versión de 123gn aquí es 3.061 fps produciendo 2.559 ft / lb ME.

Colóquelos en el programa y obtendrá 1,000 yardas en el escenario de viento estándar de 10 mph a 90 grados;

123gn SMK @ 3,061 fps ............... 77.1 pulgadas

142gn SMK @ 2,850 fps ............... 70,7 pulgadas

Por lo tanto, un poco más de seis pulgadas de diferencia ......... pero a 10 mph. Cuán importante es esto depende de la aplicación. Para disparos propensos tradicionales en papel con disparos de avistamiento, uno debe estar cerca del centro objetivo en el primer golpe y lo único que importa después es el cambio de viento entre disparos sucesivos. Hay algunas gamas del desierto del sur de los Estados Unidos que me han dicho que cambian la velocidad del viento cruzado a 10 mph, ¡pero me alegro de no haber disparado contra ellas! Teniendo en cuenta los ángulos del viento y los cambios y velocidades reales en la mayoría de los días, la cantidad de cambio de disparo a disparo es mucho menor que 10 mph, más comúnmente en el cambio equivalente de 1 o 2mph de viento cruzado.Entonces, si malinterpretas un cambio de viento real equivalente a 1 mph de viento cruzado equivalente, y los mejores tiradores de F-Class y TR leen los cambios con mucha más precisión que eso, tienen que hacerlo para obtener los puntajes que estamos viendo en estos días, entonces es un movimiento de bala de 7.1 pulgadas contra 7.7 pulgadas o poco más de media pulgada entre el par.

En el transcurso de un combate a 20 asaltos, es probable que cambie el puntaje en un solo punto para un tirador promedio si todo lo demás es igual. Sin embargo, el uso de diferentes balas de peso puede no ver todo lo demás igual. No es un hecho dado, pero con frecuencia es más fácil disparar de forma más rápida y más rápida en una gran cantidad de disparos que uno más pesado y lento.

Sin embargo, en el mundo real se trata de valores reales de factor de forma / BC de viñetas individuales. El 123gn Scenar es una bala muy eficiente para su peso y tiene un valor de factor de forma más bajo (es decir, menor resistencia) que otros en este soporte (mejor que la mayoría de los 140s también) que aumenta su BC un poco más del mismo peso SMK. Por lo tanto, tomando su actual BC en comparación con el drag más alto 123gn SMK, su deriva de 1.000 yardas a 3.061 fps es de 75 pulgadas o 7.5 por cambio de 1 mph. A diferencia de los VLD BC más largos / puntuales más altos, es una bala fácil de sintonizar para obtener precisión. También tiene otra gran ventaja, ya que es MUCHO más barato ahora que sus competidores de Berger y Hornady a menos de £ 40/100, más barato incluso que las Sierras también ahora, aunque no tanto como un ahorro. 

 

Amén!!!

 

[L B Jefferies]

Mick Miller

Thanks for starting this thread. It might help me too, since I'm also trying new powders in 260 Rem.

I'm on my second 260, having used H4350 in my first, but with the new regulations, I'm moving away from Hodgdon powders. I'm currently using 123 Scenars with N160, which give fantastic 3 shot, 100 yard, load delelopment groups, but I haven't had chance to work out how they shoot at longer ranges. They seem ok out to 300 yards, but not amazing. I stopped at a slight crunch when seating the bullet as I'm not keen on compressed loads, and have reached around 2900 fps, but with an ES of 50 or more. From what Laurie has said about N160 in 260 Rem, I suspect it's too slow for 123s, but it sounds like N150 may be too fast to get the 3000 fps I would like to be competitive against 139 gr bullets.

I hoped that you might have good results with N150, because my other options seem to be either switch to 139s to possibly suit N160 better, or go to other powders, Reloader Swiss, Ramshot? I've had sudden pressure signs with Viht 500 series powders before, so I avoid them.

Keep us posted how you get on.

 

 

[dashed]

Not long range (stalking use only) but struggled to get decent velocities with N160 for 120-130gn bullets in 260rem. Went to n150 on Laurie’s recommendation and worked much better.

[Mick Miller]

Well I have a range day tomorrow where I will combine sighting the rifle in, running the barrel in (already done 3x1shots and clean) and test velocities from single rounds loaded from 33.5 - 39gn N150. I'm only shooting singles as this is part of the running in (13 shots total) then I'll clean the barrel again when I get back, plus I think there's no point loading up five of each if I get pressure signs before I hit the types of velocity I want.

It's just a very crude trial of loads whilst simultaneously getting the crosshairs on paper and running in a barrel, all before load development really starts in earnest.

123g ELD Match are loaded to 2.790 COL with my the start of mt rifling looking to commence around 2.890 (loaded a bullet in a once fired case with a slight squeeze on the neck so that the bullet would hold and then chambered a round - crude way to tell but gives me a ballpark jump of around 0.100)

I'll post results with the caveats of new barrel and only single shot data for each.

 

[jcampbellsmith]

I've found 123gr A-Max and 44.85gr N160 works well in a couple of my 260 Rems. Regards JCS

[Mick Miller]

Well, 150 was a fat disappointment. At 33.5gn start I was getting 2300fps. With half grain steps up to 39 I finally got 2730fps. I could go higher as there are no signs of pressure (primer surfaces are exactly the same as start load with no problems extracting the case at all). However, I may ditch the whole VV thing and opt for RL19, Hornady and Nosler load data suggest it will give the velocities I'm after without going over either stated maximum charge weights.

Odd thing is that my new Tikka seems to strike the primer quite heavily compared to my X-Bolt 243, I may or may not need to get that looked at.

[DaveT]

N550 ....this will work.....accept the possibility of barrel wear if you push it too hard........barrels are not forever.......wish they were cheaper though!

[TJC]

+1 on N550. I’ve found it meters well, has predictable temp sensitivity and barrel wear isn’t nearly as bad as I’d anticipated.