need help with .308 load info
- Thread starter meatbal6
- Start date
I would suggest Lapua small primer 'Palma' brass and Re17. The Palma cases really pay off with this bullet weight letting you run at loads and pressures that see primers blow in standard large primer cases. I can get 2,620 fps from a 30" 1-10" Broughton in a chamber that is optimal for the 155gn Lapua Scenar seated right out or the 185gn Berger BTLR. It is overly short-throated for the 208 A-Max and all 210s. I have also reached 2,700 fps with Hodgdon H414, but without much accuracy with this brass and in this chamber.
GB & Brit Comonwealth Match Rifle shooters generally use Viht N550 with 210/220s and get very high MVs. 2,700 fps is achievable from a 30" barrel with Re17 / N550. I won't quote loads as it depends so much on the chamber form (freebore) used, the pressures and MVs achievable, hence safe loads.
If you're definitely going for 210s at a mile, don't use a 1-10" twist barrel. 1-11" is enough and the slower twist rate absorbs less propellant induced energy. 1,760yd with a .308 needs every BThU / joule you can put into bullet MV. Again, that twist rate is the norm for Match Rifle (.308W shot at up to 1,200yd in GB / Canada, 1,500yd in Australia).
What about throating? You must have an optimal throat for whatever bullet you choose to reduce the amount of powder holding room that the back end of the bullet takes up inside the case. That in turn means you have to decide on the bullet in advance. The 210gn Sierra MK needs a lot more throat than either of the 210 Bergers or the 208 A-Max.
Lastly, if I were you, I'd wait a little and see how the new Berger heavyweight 0.308" Hybrids work out and what throats / rifling twists work best with them. The 185 / 200gn Hybrids just going into production look winners and the 200 has the same BC as existing 210s. But, Berger's Michelle Gallagher has just asked for volunteer testers for the company's new 215 and 230gn bullets, so all being well they should be on sale in early 2012.
See:
http://forum.accurateshooter.com/index.php/topic,3771412.msg35985903.html#msg35985903
GB & Brit Comonwealth Match Rifle shooters generally use Viht N550 with 210/220s and get very high MVs. 2,700 fps is achievable from a 30" barrel with Re17 / N550. I won't quote loads as it depends so much on the chamber form (freebore) used, the pressures and MVs achievable, hence safe loads.
If you're definitely going for 210s at a mile, don't use a 1-10" twist barrel. 1-11" is enough and the slower twist rate absorbs less propellant induced energy. 1,760yd with a .308 needs every BThU / joule you can put into bullet MV. Again, that twist rate is the norm for Match Rifle (.308W shot at up to 1,200yd in GB / Canada, 1,500yd in Australia).
What about throating? You must have an optimal throat for whatever bullet you choose to reduce the amount of powder holding room that the back end of the bullet takes up inside the case. That in turn means you have to decide on the bullet in advance. The 210gn Sierra MK needs a lot more throat than either of the 210 Bergers or the 208 A-Max.
Lastly, if I were you, I'd wait a little and see how the new Berger heavyweight 0.308" Hybrids work out and what throats / rifling twists work best with them. The 185 / 200gn Hybrids just going into production look winners and the 200 has the same BC as existing 210s. But, Berger's Michelle Gallagher has just asked for volunteer testers for the company's new 215 and 230gn bullets, so all being well they should be on sale in early 2012.
See:
http://forum.accurateshooter.com/index.php/topic,3771412.msg35985903.html#msg35985903
Keith Glasscock
Gold $$ Contributor
Laurie,
Does the small primer brass do well with other powders? I have a load of Varget that is just a touch too warm for my liking in regular brass. If I work back up in the small primer version, am I likely to be able to get the velocity without the (very slight) ejector imprint?
Does the small primer brass do well with other powders? I have a load of Varget that is just a touch too warm for my liking in regular brass. If I work back up in the small primer version, am I likely to be able to get the velocity without the (very slight) ejector imprint?
The small primer brass was developed at the request of the US Palma teams who got prototype cases for a full season at least before Lapua decided to put the design into production. The idea was to reduce the MV spreads with the standard Palma load of the new model 155gn Sierra MK and somewhere around 46-47gn VarGet. With Palma only shot at long ranges and getting onto the limit of 308W 155gn bullet supersonic flight, small MV ES values can significantly reduce vertical dispersion on the target. The teams report the objective was achieved with around a third ES number reduction, so it obviously suits VarGet OK, at least in these loadings.
You could try VarGet and this brass with 210s, but I'm not sure it's ideal. I did try it with the 208gn A-Max, exceeded 2,600 fps comfortably but groups weren't as good as with Re17. With Varget and the 175gn Berger BTLR, I got higher velocities and noticeably smaller groups from Lapua standard cases and Fed 210M primers. The MV ES figures were smaller for the small primer cases with CCI-BR4s but only by a little and the standard case / 210M combo gave small values anyway.
Personally, I've found little if any benefit in using this brass with lighter bullets. It reduces MVs for any given charge weight by around 30-40 fps, so you need to work loads back up to compensate, but also appears to plateau with some powders at lower MVs than you'd expect with large primers cases. THEY DO NOT LIKE LOW TEMPERATURES! Trying these cases last November / December in temperatures just above freezing, MV spreads were large, likewise groups. At 10 deg C / 50 F performance is fine so somewhere between 2 and 10 degrees small primer / flash-hole cases lose out. This is because a small primer only just has enough energy to light up 45-50gn powder consistently and the job gets harder in very low temperatures - Lapua doesn't recommend these cases for hunting for this reason.
You could try VarGet and this brass with 210s, but I'm not sure it's ideal. I did try it with the 208gn A-Max, exceeded 2,600 fps comfortably but groups weren't as good as with Re17. With Varget and the 175gn Berger BTLR, I got higher velocities and noticeably smaller groups from Lapua standard cases and Fed 210M primers. The MV ES figures were smaller for the small primer cases with CCI-BR4s but only by a little and the standard case / 210M combo gave small values anyway.
Personally, I've found little if any benefit in using this brass with lighter bullets. It reduces MVs for any given charge weight by around 30-40 fps, so you need to work loads back up to compensate, but also appears to plateau with some powders at lower MVs than you'd expect with large primers cases. THEY DO NOT LIKE LOW TEMPERATURES! Trying these cases last November / December in temperatures just above freezing, MV spreads were large, likewise groups. At 10 deg C / 50 F performance is fine so somewhere between 2 and 10 degrees small primer / flash-hole cases lose out. This is because a small primer only just has enough energy to light up 45-50gn powder consistently and the job gets harder in very low temperatures - Lapua doesn't recommend these cases for hunting for this reason.
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