Viht data for 260rem

[mag41uk]

I was just looking at some of the new data for 260rem.

http://www.vihtavuori.com/en/reloading- ... ngton.html

I am already using 123gn and 139gn Scenars as well as 140gn SMK`s.

I have just got hold of some Norma 130gn HPBT to try.

I am confused by the varying data for N160 for the different weights.

The 136gn scenar L seems to have an unusually large maximum charge compared to the 123gn and the 139gn scenars.

I will probably try 44gns with the 130gn Normas.

Tony

[Sim G]

pe4king will be along soon..... he's burned a fair bit of this stuff in this calibre.

[Laurie]

Remember that bullet weight is only one pressure determinant amongst several. The 136 Scenar-L may have a shorter bearing surface than the 139 Scenar and/or a thinner jacket, lead core with a lower antimony content making it softer, marginally smaller shank diameter .... etc, etc.

Or then again, Lapua may have simply got a new .260 Rem pressure barrel since its original load development that produces lower pressures even though both are specified to CIP dimensions.

All that load data in a manual tells anybody is that the company's test barrel with that combination of components produced that range of pressures. (It often doesn't even tell you what MVs the pressure barrel produced as many companies now use a factory rifle for that as SAAMI / CIP test barrels and a universal receiver more often than not produce much higher MVs than the data users get thanks to the specifying body listing a longer barrel than found on most out of the box products, tighter bore / groove dimensions, and shorter throats than manufacturers actually give mass produced products.)

Loading data is a guide, no more no less.

[pe4king]

I have settled on 139 gr alpha scenar with 37 gr of N140 loaded to 2.826 in my Tikka T3 it seems the best of the bunch, I have also tried TR140 the Vit has the edge over it.
I have also tried Elcho 17, and wasn't keen to be honest

[oaken]

I had a .260 built and chambered for the 139 scenar but found that I couldn't get the velocity I expected before pressure signs were evident. Using N160 in a 27 inch barrel I was getting ejecter stamps on the brass at 2730 ft./s.
Switching to the 123 grain scenar, I have worked up a load that will do 2880 feet per second with no signs of pressure. So despite the inferior BC, the 150 ft./s gained gives a distinct long-range advantage. 3.5 mins less elevation at 1000 yards
Sadly, the scenar bullets have been outlawed at the RRC (Roundhouse)competition due to the damage they cause to the steels so am about to start working up loads with the 123 grain SMK's. Hopefully these will work as well as the scenars.
Hope this helps.
Rup

[mildot77]

I ran a .260 with N165 and was getting low 2800fps with the 142gr SMK.

[DaveT]

I had a .260 built and chambered for the 139 scenar but found that I couldn't get the velocity I expected before pressure signs were evident. Using N160 in a 27 inch barrel I was getting ejecter stamps on the brass at 2730 ft./s.
Switching to the 123 grain scenar, I have worked up a load that will do 2880 feet per second with no signs of pressure. So despite the inferior BC, the 150 ft./s gained gives a distinct long-range advantage. 3.5 mins less elevation at 1000 yards
Sadly, the scenar bullets have been outlawed at the RRC (Roundhouse)competition due to the damage they cause to the steels so am about to start working up loads with the 123 grain SMK's. Hopefully these will work as well as the scenars.
Hope this helps.
Rup

The 123g SMKs work well ...I am using N550 ....just trying to decide between 41g, 41.5g, 42.5g and 42.8g all of which group .5moa or less from my initial trials between 40.5g and 43.3g....no pressures even at upper scale although I am loading longer than book COL max. Previously I was using 139g Scenars but am having to rework for the RRC also.

[ovenpaa]

I shoot a pointed version of the 123 Scenar out to 1200 with a 6,5x47 at around 2900fps, I can go quicker which gives slightly better accuracy but I have seen a couple of pierced primers so until I get a chance to bush the firing pin aperture the lower load will have to suffice. On a still day they are superb, on a windy day expect to get hammered by the 180 VLD shooters

Rup, that is an interesting comment on the 123 Scenar and damage to steels, was it significantly more than other bullets?

[oaken]

Yes, fairly extensive testing was done on the steels and the scenar is definitely more destructive than other bullets. There is also the worry that because they are harder there is more chance of ricochet.