Savage model 12 6BR ??

[broncman]

I picked up a model 12 6BR in 12 twist factory takeoff. Been working on loads and wondering WHY the long throat on a 12 twist? What is the optimum bullet weight for these factory barrels with a 12 twist and long throat. Trying to seat anything but flat base bullets to the lands leaves very little left in the case neck!

80 grain Berger Varmints in the lands makes 1/4" groups. Tried some 75 SMK and some 65 vmax but cant get anywhere close to the lands and have more than 1/8" to 3/16" bearing surface in the case. the 65 vmax has very little in the case and shot like crap. Always hear about shooting the 6BR from the lands? Going to try a jump, but curious as to why the long throat and slow twist?

 

[jonbearman]

It is throated for the lawyers. I jump mine about .050 in a different gun and I can still shoot under .3 with a worn throat.Have you tried the 68 grain match bullets like berger or such with h322?

 

[broncman]

It is a takeoff barrel so no idea which particular model it came from. Just says Model 12 6BR 12" twist.

Only tried 80 bergers, 75 SMk, 65 vmax as that is all I have been able to locate right now. Only powder I have is varget, N145, rl 15. Cant find any other suitable powders available.

I will try the jump. Just crazy that they would throat so long for lightweight bullet/twist

 

[Shynloco]

Broncman,
I was reading an article a while back (might have even been a post up here) that says that Savage in particular, makes their throats l o n g (.100 longer) in order to accept a wider range of bullets weights, REGARDLESS of the twist factor. A 12 twist (as you know) is right between a 9 and 14 which many guys use. But my guess is that someone decided to get creative and HOPED that they could shoot both the shorter 6mm bullets (say 68 gr for short distance say 100 - 200 yds and at the same time shoot the 105 -107's for the 600 - 1K shooting. Whether that'll work is another story depending on the rifle or perhaps even custom made bullets that the guy who did the work, had on mind. Just a guess on my part but I can't imagine any other reason why someone would do that, other than what the article I read suggests.

Alex

 

[GSPV]

In my experience, twist rates for 6 BR tend to be 8, 10, 12 and 14.

Powder case fill, neck length, bullet length, freebore, jump/jam and twist rate all interact for the complete solution.

You might do a chamber cast or use a really long bullet to figure out the freebore. From there, you can figure out what you want to do.

If I couldn't have the option to get the bullet that I wanted 10 thou into the lands, I'd at least talk to my smith about setting the barrel back. Right off the top of my head, I'd guess that it wouldn't be cost effective. But, maybe you have a way to do it without out-of-pocket expense.