6mmBR bullet weight question

[Goofycat]

I am considering the purchase of a 6mmBR, but read on this site that the cartridge is suitable for 50-108 grains bullet weight. Since the 50 grain bullet is shorter than the 108 grain bullet, wouldn't it be a problem seating it (the 50-grainer) so that it didn't fall out of the case?

Also, how can one barrel twist accomodate all bullet weights within the 50-108 range?
In other words, I don't understand how I can order a rifle with a particular barrel twist and expect it to shoot the various bullet weights offered. I plan to use the rifle for coyotes (mainly) and ground squirrels (occasionally).

Another thing: An article in Varmint Hunter's magazine from many years ago mentioned that if I ordered a rifle chambered in 6mmBR that I should ask that a short-throated reamer be used during construction of the barrel to accomodate for any future erosion problems that might disallow for bullet seating after a certain amount of erosion....at least when using shorter, lighter-weight bullets. I have always thought that bullets for the 6mm caliber were customarily seated way out for lighter case-grip, producing a chance for better accuracy.

So, would I want to ask that the chamber be constructed with a short throat and expect that the barrel twist chosen by the builder would accomodate virtually any bullet weight below 100 grains and not worry about it?

 

[NorCalMikie]

First off, I like as much bullet in the neck as I can get. The throat will only get longer.
Pick the bullet you plan to shoot, make a dummy round and have the barrel chambered to that.
"With bullet neck contact in mind", you can't shoot 40s & 45s and shoot 105s as well.
A 1-8 twist will shoot just about any weight bullet with accuracy that's hard to believe. You want the bullets stuffed into the lands and seated to the shoulder neck junction. Works for me but YMMV.
You want to be able to shoot heavy and light bullets? Get 2 barrels. One set up throated to do the heavies and one for the light bullets. Can't go wrong that way. ;D

 

[SS427]

Pick the bullet weight you want to shoot first, and that will dictate how long a throat you need and the twist rate. Which bullet weight should be decided by what distance you want to shoot the most.

In theory, you want to spin the bullet just enough to stabilize it for optimum accuracy. Faster RPM will emphasize any defects in the bullets and detract from accuracy. Too fast a twist can even make the very light bullets come apart in flight. So while an 8 twist barrel can shoot 70 grain bullets accurately, a 12 twist or even a 14 twist barrel should shoot those same bullets even more accurately. That is why 100 and 200 yard 6PPC barrels are 13 to 15 twist and not 8 twist.

If you want to shoot 600 yards, then 95 and 105 grain bullets are what you need and an 8 twist barrel is the answer. However if you throat the chamber to shoot light bullets at the lands, the heavier bullets end up way down inside the neck and you lose powder capacity. In my opinion that is compromise all the way around.

For out to 300 yards, the 12 or 10 twist barrel is a good compromise. You can have a short throat so light bullets can be loaded to the lands or jammed, yet with the middle weight bullets you don’t lose so much powder capacity that it compromises velocity. For coyotes and squirrels, this is probably the best choice.

For 100 and 200 yards, a 14 twist might be your best choice. The heavier bullets don’t have a real wind advantage until you get out past 200 or 300 yards anyway, so you may as well shoot the lighter bullets. Less recoil and they are cheaper.

The final thing is a slow twist won’t shoot the longer heavier bullets. But a fast twist will shot the lighter shorter bullets. The best answer is two barrels, otherwise at one extreme or the other you will be compromising. Even better – two guns. Run that past the wife and see how it flies!

 

[Travelor]

I have three 6mmBR's and I shoot nothing by the 105-107 gr weights with 1:8 twist barrels. I shoot these bullets at all distances and they shoot wonderfully. Both Berger and Sierra bullets shoot well wiht a slight jump.

In my opinion, the chamber reamer should be "normal" length as this will provide optimum performance and this cartridge is easy on barrels and throats. I think the issue of neck diameter is more important that anticipation throat wear. I would get a chamber reamer that lets you shoot factory cases after a slight clean-up wiht a neck turning tool.

When you get your gun, try 30 gr of VARGET with a 105 grain bullet in Lapua cases and you will be amazed at the accuracy.