Barrel Specs 101 -- importance of various specs, with bullet type and weight

[BlueWater]

You aren't going to to shoot the difference between a 7.5" and 8". Slightly more stability is always better then slightly not enough but in your case either will more than enough to get the job done unless you decide to try one of the heavier bullets which really don't suite the straight 6BR.

.236"-.237" flip a coin. I have both and both win matches. I get the same speeds from both. Zero difference in accuracy.

# of grooves, again records have been set with all of them. Pick one of the top tier barrel makers and go with whatever they specialize. They have dome their R&D to make their preferred number of groves work. Ford, Chevy, Dodge. You just have to pick one.

Contour, no effect on accuracy as far as the barrel is concerned but weight is moderately important for how the rifle balances which has a bit to do on how the gun handles on the bags.

Yes! It's all ver confusing until you have some miles on all of it. Really the biggest effect of all of it on accuracy would be not having enough twist, which at 8" or slightly faster you enough. You'll get way more out of LOTS of shooting and learning to keep it in tune than in thinking there is a Holy Grail of the perfect combination of barrel specs.

Certainly don't think there's a "holy grail" of perfect specs; never have. Just wondering what people's actual choices are with 6BR in practice, if seeking moderate accuracy at distance.

Twist / Stability -- Always thought slightly more was better than not quite enough. Uncertain if in the case of 6BR there's too much of a good thing, but all the barrel makers seem to specify in 6BR down to 1:8" or at most 1:7". I'm assuming they wouldn't offer it if it couldn't work. As others have suggested, with the barrel maker's recommendations and output from the Berger stability calculator, the weight ought to point to the proper twist. Obviously dependent on preferred bullet weight. I'm all for the 103-108gr "standard" bullet choices, out there, for LR BR, and suitable twist.

Bore diameter -- Seems there's a typical experience, that there's little to no practical difference with .236" vs .237" for the bore.

Grooves -- The few that have posted specifics seem to feel there's no difference between them. Good to know. Some have posted elsewhere that a particular one was worth worrying over. I've only done 4-groove on a prior re-barrel, so I wasn't aware of whether the various choices, these days, were worth evaluating.

Contour -- I've always thought, generally, that more steel (diam.) equates to greater stiffness. Assuming it's of a length that matches the caliber's harmonics. Though, as some suggest, it's probably far less important than balance, behavior on the bags, etc.

I appreciate the lists of equipment people have posted, from time to time. Helps for selection, at least, of make/model of choices, if not particulars beyond that.

 

[BartsBullets]

Am looking for a "Barrel Specs 101" type summary of the details of barrel selection, when re-barreling for, say, the 6BR caliber. If there's a great technical summary, someplace, I'm all for it. (Haven't found one, yet.)

Assumptions:
6BR caliber
Heavier, longer, VLD-type bullets preferred (100-115gr 6mm)
Distances in the 300-1000yd range


Twist rate -- I appreciate that the twist-rate needs to be fast enough to stabilize. But, is there an "optimal" range of twist-rate that'll work for certain bullet weights? Can a twist-rate go too fast, for 6BR? (ie, Some bullet makers might suggest 1:7.75" twist for a 6mm bullet of a given weight, but a barrel maker might only do 1:8" twist and 1:7" twist.) Don't understand what the limits are, here, with twist-rate.

Groove count -- With the 6BR, is there a typical or preferred groove count (ie, 4, 5R, 6) that people choose for the heavier, VLD-type bullets? The barrel makers seem to offer two or three different groove counts for the caliber. Uncertain which would make sense, depending.

Bore diameter -- (ie, .237" or .236".) Is the bore diameter going to matter that much, for a given maker, model, weight of bullet selected? For example, a Berger 108gr Hybrid Target (VLD) versus a Sierra 107gr MK versus a Bart's 103gr Hammer (VLD), etc. Do certain bullets seemingly "prefer" this or that bore diameter?

Freebore -- How important is freebore choice, if the heavier (100-115gr), longer, VLD-type bullets are going to be used? Is there a preferred freebore, where this type of 6BR bullet seems to perform better?

Barrel contour/diameter -- Plenty of choices. Uncertain to what degree, if any, barrel diameter and profile selection makes with respect to bullet performance, in the heavier-VLD, longer-distance arena. (I'm assuming, say, a lighter-weight profile 28" barrel will behave a bit differently than a heavy-Palma or straight-contour 28" barrel of similar make, but I don't know.)

Insights? A "Barrels 101" write-up somewhere?

Here you go.

Twist Rate : 8

Groove : I prefer 4 or 6

Freebore : 104

Bullet weight 103-105

Diameter: 236 or 237 doesn’t matter good barrel is a good barrel.

Barrel Contour: I shoot HV. Contour often depends on sport. A Lot more straight contour barrels on F Class Guns for example.

 

[BlueWater]

Thank you, to those who are specifying the details of the barrel choices you make with the 6BR. Helps to see which details people are bothering with.

 

[Rat Rifle]

Did I hear someone say “bottom line” ?

 

[snert]

yup

 

[Ccrider]

Great post combining information from many previous post. Your questions have been answered by some of the best. Let us know how your barrel shoots.

 

[10XSHOOTER]

I have a 6 Norma Dasher. 1-8 Krieger, 5R Remington varmint taper 26" Dan Dowling (inventor of the Dasher) smithed the rifle. I shoot moly Sierra 107's. I believe it's a .100 free-bore reamer. Have not shot it to 1000yds yet. It's one of the big boy's at 600yds!

 

[JEFFPPC]

A lot of good information and experience on this thread. I will throw in my thought after a lot of barrels in 6brs and 6brx's. I have settled on .237, 4 grove for 105 class bullets. Contour is whatever fills your needs and allows you to make weight. I have had several 5R style barrels, saw no gain from them. 26 to 28 in length does not seem to offer much in velcity gain and accuracy is based on each particular barrel. Most important perhaps is proper load tune to allow your barrel to reach its potential. Get your own reamer based on the bullet you want to use.

 

[RICK SMITH]

A lot of good information and experience on this thread. I will throw in my thought after a lot of barrels in 6brs and 6brx's. I have settled on .237, 4 grove for 105 class bullets. Contour is whatever fills your needs and allows you to make weight. I have had several 5R style barrels, saw no gain from them. 26 to 28 in length does not seem to offer much in velcity gain and accuracy is based on each particular barrel. Most important perhaps is proper load tune to allow your barrel to reach its potential. Get your own reamer based on the bullet you want to use.

.237 4 grove is where it's at. 26-28. .104 freebore for 105 class bullets

 

[JEFFPPC]

My reamer is the original Chrone which was set up for 68 gr benchrest bullets. I seat my bullet of choice with the pressure ring halfway up the neck and my barrel smith, a friend who is a tool and die maker, uses a throater so the lands just put a tiny mark on the bullet. This gives me plenty of leeway to adjust seating and have the pressure ring remain above the neck shoulder junction leaving max powder space.