Thanks a lot for your fast & accurate reply !
Favorite powder for .308?
- Thread starter zzr600
- Start date
paulbshooting
Well-Known Member
N140 with 150g Nosler BT, don't have load book to hand but something like 44 grains, 10 thou or so off lands.
The RS 52 would be acceptable in terms of precision but its velocity is "limited" at Vo=3000fps max for a 130 TTSX . Concerning the 110 TTSX the accuracy ( at least in my rifle ) is not the one I would expect.
So ...
I'll most probably conduct different tests with the V.V. 530 (double base) which seems to provide enough velocity for both the 110 & 130 TTSX but I do ignore ererything on the possible accuracy and why not consider the advice from Alantoo with the V.V.135 which is promising too.
Enjoy your day !
I get excellent results with 46gr of N135 under 150gr SGK and Nosler Accubonds.
CH
CH
Did anyone measure the velocities with the V.V. N135 ( which is named by some of you ) ?
Thanks a lot in advance
Thanks a lot in advance
It's nearly impossible to categorise expected results (potentially MVs aside) by powder type. All have pros and cons and then there is the issue of whether a particular bullet likes or dislikes the way pressure builds up in your rifle. There are often a small number of 'go to' powders for a cartridge and sometimes for an individual bullet in that cartridge, but 308 Win is the very reverse given its inherent flexibility. Over the years I've probably used over 20 powders in the cartridge and rarely been unhappy with any. Bullet choice usually determines results (in terms of precision) to a greater degree than powder choice assuming the powder is inherently suitable in its burning rate.
As a general rule, you can say of the three types.
Ball types are easy to meter on mechanical powder measures so are the first choice of some for this reason alone. Traditionally they were dirty burners as nearly 10% of their composition by weight used to be non-combustible, but that has changed completely in recent years with the new grades that have appeared. Ramshot in particular is clean, but none is bad these days. However, they do tend to be more finicky as a rule with a narrower efficient-pressures band and a more sudden transition from there into excessive pressures as charge weights rise. They also tend to be temperature affected so performance may suffer, or excessive pressures encountered, when there are large variations in ambient temperatures. With some exceptions (such as US XTC competitors who load vast quantities of 223 on progressive presses) they are rarely chosen by match shooters. On the other hand military buyers (in particular the US DoD) often specify ball types because their accurate metering gives lower charge weight variations than for extruded types and hence a smaller chamber pressure range which is highly desirable in modern automatic weapons.
Single-based extruded is the plain-Jane variety and if it has the right specific energy and specific density characteristics (to pack enough energy into the case to give the required MVs) is often the best. The old bugbear of poorly metering long sticks has been at least partly overcome through the development of 'short-cut' varieties and that also improves density if it is needed to pack more powder into the case than it happily holds. (This is a major issue with 308 Win with very heavy bullets in long-range match shooting where maximum MVs are needed. Many powders that are otherwise ideally suited to the application fail because the case won't physically hold enough to achieve those MVs - not an issue with deer loads though.)
Enhanced energy or double-based extruded grades largely exist to increase performance to meet that single-based downside. Adding nitroglycerin increases both specific energy and density levels, the latter through increasing the kernel weight at the molecular level making a given size of kernel heavier. When allied to short-cut kernels this type can enhance MVs substantially where case capacity is a limitation as well as producing higher MVs for a given maximum pressure. The downsides are that they seem to be a bit less flexible than their single-based equivalents often needing higher pressures / charges before they get into their 'comfort zone' and operate consistently, and if the extra performance on offer is fully used barrel wear increases. There are claims that nitroglycerin in the mix makes the powder more or less temperature affected, although it seems to be mostly accepted now it is more affected all other things being the same. (Norma claims the opposite!)
As a rule some nitroglycerin in the mix seems to increase powder storage life and the powders are less likely to see moisture levels change over time. I suspect that modern health and safety requirements such as the EU 'REACH' have also pushed manufacturers towards this type albeit using small quantities <10% by weight. Many of the recently introduced grades (such as all of the new REACH-compliant IMR 'Endurons' and pistol powders) are of this type with modest nitroglycerin levels in the recipe.
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