N140 or N150 in 308
- Thread starter big ears
- Start date
Not really. It's a myth about short barrels need fast powders and long ones slower burners. The internal ballistics relationships - combustion chamber to bore ratio and bullet weight have a much greater effect on powder selection. Moreover, N140 and N150 are pretty close together in their burning rates. In 308 Win, both see 99-100% charge burn in 20-inch barrels and if you run combinations through QuickLOAD, the predictions are for the relationships to remain pretty constant between say a 20 and 30-inch barrel, although obviously both produce higher MVs in the longer barrel.
Very helpful, as usual. I was letting my thoughts wander away from the original query that was limited to the two powders mentioned.
big ears
Well-Known Member
OMG I started this in 2014!! So much water under the bridge since then.
The key to this premis is that you have a near perfect burn rate of 99%+. If the burn rate is low <95% it will have an effect on MV in short barrels. I've seen this in my 6.5x55 with a 20" barrel and although everyone quotes N160 it wasn't deer legal when I put it over the chrono and changed to N150. Like you I work through QL and try and match %age burn with different powders.
BE
ABOLT
Well-Known Member
This load 44.5g
44.5 g vit 140 on a 165g Sierra on 308 what was FPS please and which rifle !I am putting 42.5g giving me 766m/s 2514 FPS but want up speed a bit!
Littlekilmory
Well-Known Member
Some big variations in case volume makes quite a difference - new lapua is 55.6, Winchester perhaps 56.3.
Using the lapua brass I was surprised to see 2645 FPS from my 600mm Steyr SSG08 barrel with the following: 43.7gr VV N150, Sierra 168gr TMB, COAL 2.94. This shoots tiny groups and, according to Strelok, is supersonic to 1000 yards (just!). Lapua‘s data suggests 44.5gr to achieve this.
I load N140 for the lighter bullets, generally Lapua scenario L. Same cases, 42.2gr N140, coal 2.82, 155gr scenar sees 2650fps (happy node on the rifle). Again, Lapua says you need 43.4 (max) to get there.
Both standard CCI primers.
Oh, worth a look at one of the barrel life calculators: they all suggest 5,000 plus rounds - not something you see in hot 6mm stuff.
Using the lapua brass I was surprised to see 2645 FPS from my 600mm Steyr SSG08 barrel with the following: 43.7gr VV N150, Sierra 168gr TMB, COAL 2.94. This shoots tiny groups and, according to Strelok, is supersonic to 1000 yards (just!). Lapua‘s data suggests 44.5gr to achieve this.
I load N140 for the lighter bullets, generally Lapua scenario L. Same cases, 42.2gr N140, coal 2.82, 155gr scenar sees 2650fps (happy node on the rifle). Again, Lapua says you need 43.4 (max) to get there.
Both standard CCI primers.
Oh, worth a look at one of the barrel life calculators: they all suggest 5,000 plus rounds - not something you see in hot 6mm stuff.
A Remy 700VS shortened to 24" and an oal of 2.820" gives 2725 fps last time I checked.
This is a significant speed gain for you so work up steadily as safe in mine but may not be in other peoples etc. etc.
Note the oal length which is safe max length for mag fit.
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