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6br twist rate

Kevin1990

I see a lot on this, but the question is always worded. “Will this work with this twist? Rather than what is optimal.”

So just a general consensus on a 6br. What twist rate would you use Exclusively for 68gr Bullets?

I understand people shoot them with 1-8 twists just fine, but I’m contemplating a short range 6br.
 
13.5-1 to 14-1 work best, I prefer 13.5-1 for 68 grn BT. But both will work. I think with the longer BT the 13.5-1 is a little better when the winds pickup, and is a little more forgiving to fouling.
 
I'll go against the grain a little, as usual and say that I prefer a 1-12 for 68 class bullets. We're splitting a very fine hair here but you gain a small bit of bc and as long as the jackets are good, I've seen no down side at all to it. I've tested this quite a lot! I think the whole "ideal" twist thing is over rated, to a point. No, I don't want an 8 twist but I also don't think the old school thought of minimal twist is right either. If results alone are how we want to measure things, I have three National championship agg wins as well as a grand in back to back to back years as soon as I went to 12 twist bbls, fwiw. Of course there are other variables so I don't think that should be the only thing used as a measuring stick, but it shouldn't be ignored either.

I've been testing a 10 twist and go figure...it shoots 68's better than the heavies or "ideal" weight for twist bullets. It also shoots 80's better than the heavies. On a one off basis, it's easy to conclude that twist isn't as critical to accuracy as bullet length. Of course, you can't shoot the heavies in a slower twist, so....Bottom line, I think bullet length/balance is more detrimental to peak accuracy than twisting a little faster than minimally required.

I will say that the 10 twist is close but not quite as good as the 12 or 14's, fwiw, with the lighter bullets. The whole point of testing this was/is to find that point of diminishing returns. IOW, how fast is too fast. In this one off case, I'd say 10 is too fast but 12 is great and is what I consider to be ideal. Not too fast nor too slow. Just because something is popular doesn't always mean best, but that it needs to be tested. We're not shooting the same jackets as we did even just a few years ago, so minimal twist is less critical and "may" be of less value than the gained bc of the slightly faster twist. Other calibers and heavier bullets have other factors too, like torque, but I can't feel the difference of a 12 vs 14 6mm and the results have been supportive. I'm staying with 12 twists until I have reason to go back to the 13.5 etc. Trust me, I will only shoot what I feel gives me the best chance of winning. Without testing, we don't know much. There are numerous example of BR gospel that don't test out to be fact...or the only way. So test, test, test.

I'm not alone in this as there are some well respected names in the game as well as bullet makers who agree.
 
Totally agree with testing to see what works best in a given rifle. The tighter twist "may" work well with the 68 gr. bullets BUT, when you consider what the short range bench rest shooters are mostly using the 1 - 13.5 & 1 - 14 twist is still dominate across the board. As you said though just because it's used more does not mean it is always the best choice.
 
I agree with Mike. Last fall after reading Randy Robinettes thoughts I did several twist calculators on some bullets. I have a 12 twist chambered up for my PPC. It is going on as soon as I shoot the last 100 Eubers I have been using for the last. 25 years.
 
gunsandgunsmithing said:
I'll go against the grain a little, as usual and say that I prefer a 1-12 for 68 class bullets. We're splitting a very fine hair here but you gain a small bit of bc and as long as the jackets are good, I've seen no down side at all to it. I've tested this quite a lot! I think the whole "ideal" twist thing is over rated, to a point. No, I don't want an 8 twist but I also don't think the old school thought of minimal twist is right either. If results alone are how we want to measure things, I have three National championship agg wins as well as a grand in back to back to back years as soon as I went to 12 twist bbls, fwiw. Of course there are other variables so I don't think that should be the only thing used as a measuring stick, but it shouldn't be ignored either.

I've been testing a 10 twist and go figure...it shoots 68's better than the heavies or "ideal" weight for twist bullets. It also shoots 80's better than the heavies. On a one off basis, it's easy to conclude that twist isn't as critical to accuracy as bullet length. Of course, you can't shoot the heavies in a slower twist, so....Bottom line, I think bullet length/balance is more detrimental to peak accuracy than twisting a little faster than minimally required.

I will say that the 10 twist is close but not quite as good as the 12 or 14's, fwiw, with the lighter bullets. The whole point of testing this was/is to find that point of diminishing returns. IOW, how fast is too fast. In this one off case, I'd say 10 is too fast but 12 is great and is what I consider to be ideal. Not too fast nor too slow. Just because something is popular doesn't always mean best, but that it needs to be tested. We're not shooting the same jackets as we did even just a few years ago, so minimal twist is less critical and "may" be of less value than the gained bc of the slightly faster twist. Other calibers and heavier bullets have other factors too, like torque, but I can't feel the difference of a 12 vs 14 6mm and the results have been supportive. I'm staying with 12 twists until I have reason to go back to the 13.5 etc. Trust me, I will only shoot what I feel gives me the best chance of winning. Without testing, we don't know much. There are numerous example of BR gospel that don't test out to be fact...or the only way. So test, test, test.

I'm not alone in this as there are some well respected names in the game as well as bullet makers who agree.
Click to expand...
Thanks for sharing this Mike. I have been planning on trying a 1/ twist ever since reading Randy Robinette’s post explaining that ballistically 12 twist was better.

My personal experience is that bullet length matters more than weight. I have had a 13tw barrel that would not stabilize 68gr. Berger’s, but would stabilize 70gr Sierras that were shorter than the Bergers.
 
Mucho eazy to talk about bullet weight : twist rate . . . really, it's ALL about bullet length : twist rate.
For any bullet weight which a given jacket will accommodate, the mass is simply, "along for the ride".
For arguments sake, let's presume that all jackets are of BR quality - that is, maximum wall-thickness variation <0.0003".

Way back, to the beginnings of J4 jackets, and the decision to make 68 Gr. bullets using the .825" long jacket, none other than Mike Walker wrote a letter, published in PRECISION SHOOTING, admonishing the BR community, that is was/is a mistake to make a 68 Gr. bullet using this jacket length [combined with 1:14" twist] and expect the best precision.o_O

Mr. Walker stated that the jacket should not exceed 0.810" long. In that era, the predominant jacket was the .810"Sierra, which featured(s) a radius base, as opposed to a flat base (J4), thus, once cored and flat-based, the .810" Sierra made/makes [about] the same finished bullet length as a .790" long J4 - around 0.815-.820" long. The .825" J4 jacket will run about 0.845-.850" long, roughly 1/32" longer.

"So, what" - they're both 68 gr. - right? To attain the same gyroscopic stability, the .030 - .035" longer bullet 68 GR. bullet demands a FULL 1.0" faster twist rate, or, 1:13". Mr Walker believed we were smart enough to understand . . .

Instead, we entered the realm of constantly searching for the highest level of precision with a marginal/mismatched platform. The HUMMER concept, already born, was baptized - buy a dozen barrels and get one HUMMER - and to this day, people adhere to Einstein's definition of insanity: keep doing the same thing and expect a different result.;) Every dozen barrels, or so, one gets a [so called] Hummer*.

Or, do some homework and simply obtain the correct twist rate for the bullet(s) you intend to use. Regardless of your favored barrel maker, you'll be pleased with the much improved Hummer to BUMMER ratio.

6mm, FB bullet, >.840" long: 1:13" (Sg 1.4), or, faster. Or, use shorter jacket*. Pretty straightforward - Mike Walker was, "spot on". RG
 
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JEFFPPC said:
I agree with Mike. Last fall after reading Randy Robinettes thoughts I did several twist calculators on some bullets. I have a 12 twist chambered up for my PPC. It is going on as soon as I shoot the last 100 Eubers I have been using for the last. 25 years.
Click to expand...
I think you'll be quite happy with the 1-12s. Maybe even more so over the course of several bbls. I just don't have any more "average" or bad barrels, it seems. I just wish I could shoot what I have better...and lately, just shoot at all. Lol! For me at least, twist rate is far less important to how I shoot than the work I put into shooting better. The more I shoot, the better I shoot. With virtually no exceptions to that.
 
DaveTooley said:
I remember when we transitioned to the .825" jacket from the shorter jackets. All of a sudden groups in the 0's pretty much disappeared. Enter the .790" jacket. I was using the Sierra .810" back then.
Click to expand...
Would that time coincide with the timeframe of going from mostly 14 twists to 13.5? It would seem logical to. My apologies if Randy addressed that above.
 
Kevin1990 said:
Gotta be honest with you fellas. I won’t be able to shoot the difference no matter the twist. I guess I just want optimal equipment for the intended job.
Click to expand...
That's an honest reality for most of us, even if we don't admit it. I was talking to Randy Robinette earlier and this was hit on. It takes a bit of experience and a very good rifle to tell if there is any advantage or disadvantage. I've worn out maybe a half dozen barrels or more(more like 10 bbls) coming to my conclusion that...I can't tell a difference but if anything, I lean toward the slightly faster twist. There are other reasons as well. Some were hit on in mine and his posts above. One thing that is obvious but I think has benn unmentioned is, I like the ability to shoot 80's in a 12 twist. That's just not a possibility in a 14...or shouldn't be...fwiw.

The other side of not being able to shoot the difference is that...that's what I would hope to be the case, at worst. A difference that is an improvement over a 13.5-14 is best case. Yes, I'm in the latter but hard and expensive to prove. So it's a win if there's no down side!
 
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