2 Newby questions on load development with a 6BR for F-Class competition

[ClayC]

I have done a lot of reloading over the years and I shoot a bit of competition (FT/R 600y W/ .308) Well I'm starting to get into F-Class competition using a 6BR and I'm doing load development. The rifle is a Savage 12 F-Class Chambered in 6BR. I figured this was a good entry gun to get started with.

Question 1:
I have my chronograph all ready to go. I'm using Varget and I'm starting my loads at 29g and going to 31.5g working my way up in .5g increments. What is the highest standard deviation I should be expecting from a 6BR? Should the 10 shot group vary no more then 10pfs? When I did load development on my .308, I was pretty forgiving allowing about 20fps standard deviation but I was told to expect much more from a 6BR.

Question 2:
Now some guys on here are suggesting seating the bullet with a jam at about .010 to .015 I have always shot a 308 so jamming the bullet is a bit of a foreign concept. My question with that is; I turn the case necks and put as little tension on the bullet as I can with a Forester Precision Plus Neck sizing dye. Most guys I know do that. If I were to jam the bullet into the lands would the lands just push the bullet back into the case?

[foxx]

I am also just getting started with a 6BR. It's a fine cartridge ad a joy to shoot.
There's a lot of good info on 6BR here:http://www.accurateshooter.com/cartridge-guides/6mmbr/

To answer #2 Try jamming. Reports are that it helps. I don't really care why. :) Depending on your neck tension, the rifling might push the bullet into the case, but to test it, chamber a round, then remove it and measure from the ogive. Maybe it will, maybe it won't. If it does, it still might shoot well that way, you gotta test it and see. Only issue might be that the bullet might stick in the lands when trying to remove the round from the chamber, so have a cleaning rod and brush available to clean out spilled powder from the chamber. Also, you MIGHT be able to run a dowel down the barrel and compare it's length against the tip of a chambered bullet seated short of the lands with one you intended to seat deeper into the lands. (that way you don't have to remove the chambered rounds, risking separation and subsequent powder spill.) Might want to do this will a "dummy" round. :)

My guess is it will seat the bullet into the case more. If so, it may very well like it that way. Based on reports that jamming into the lands is better, you may want to add neck tension to some of them and see if it likes being jammed. Point being, it is not dangerous to do so and you'll never know till you try it.

[foxx]

Also, not to beat you up, but WHY do you turn your .308 necks for as little neck tension as possible? It's my understanding that people turn necks only after confirming THEIR rifle shoots better that way. Or they have tight chambers and need smaller OD necks so as to fit the chamber. Or, just for the sake of trying to get more consistent neck tension, but lighter tension is not necessarily better than heavy tension. Usually what matters is CONSISTENCY. From what I've read, not everyone benefits from it. Some like light tension so they can seat them long and then allow the rifling to seat the bullet deeper so they know it's always seated against the lands. But again, if it doesn't actually shoot better against the lands, it's not worth the effort. Finally, just because my barrel shoots better that way, does not mean yours will. There is no scientific explanation that says a cartridge OUGHT to be constructed a certain way. All that matters is that you find what works for your barrel and construct them that way.

Good luck.

[strut64]

I started in march to tune up a 6 BR and have the following suggestions. Using 0.5 gr increments is too wide. Try 0.3 or so because you can miss a node. I found that using Berger 105 hybrids the best seating depth was a light touch, Not hard jam. I also found that neck tension built on successive firings with a conventional die. I now have a redding bushing die. You must have a bullet comparator and a micrometer seating die. Half way through the process I had to start over due to pillaring and actin bedding The action

[ClayC]

Also, not to beat you up, but WHY do you turn your .308 necks for as little neck tension as possible? It's my understanding that people turn necks only after confirming THEIR rifle shoots better that way. Or they have tight chambers and need smaller OD necks so as to fit the chamber. Or, just for the sake of trying to get more consistent neck tension, but lighter tension is not necessarily better than heavy tension. Usually what matters is CONSISTENCY. From what I've read, not everyone benefits from it. Some like light tension so they can seat them long and then allow the rifling to seat the bullet deeper so they know it's always seated against the lands. But again, if it doesn't actually shoot better against the lands, it's not worth the effort. Finally, just because my barrel shoots better that way, does not mean yours will. There is no scientific explanation that says a cartridge OUGHT to be constructed a certain way. All that matters is that you find what works for your barrel and construct them that way.

Good luck.

Honestly, consistent neck tension more then anything. Its pretty much that simple. I know there are a lot of opinions out there. For myself, I use Lapua brass and every lot I have ever trimmed had inconsistent neck thickness. From there its just my education. I was taught by the guys that I shoot with that you just neck resize. Seat your bullet, measure the neck and use a bushing a bit smaller.
So basically I learned that's what to do, Midway and everyone else sells the items needed to do it and the top shooters I personally know told me to do it so it was just what I did. Pretty simple.
Now that being said, the guys I shoot with win matches when I shoot with them at AEDC in Tullahoma, TN; Miami, OH and various other places. They are shooting High Master @ 600 yards with a 590-22X or higher score. My personal best is 575. Not the top of the pack but respectable.

[ClayC]

I started in march to tune up a 6 BR and have the following suggestions. Using 0.5 gr increments is too wide. Try 0.3 or so because you can miss a node. I found that using Berger 105 hybrids the best seating depth was a light touch, Not hard jam. I also found that neck tension built on successive firings with a conventional die. I now have a Redding bushing die. You must have a bullet comparator and a micrometer seating die. Half way through the process I had to start over due to pillaring and actin bedding The action

I do in fact have a bullet comparator and a micrometer. I got lucky and bought 1000 105g Berger Hybrids all in the same lot so I lucked out there and that is what I have been using. I have to admit, that Redding micrometer is the best I have ever used. I keep measuring though the whole series but I generally never have to readjust once its set.

Did you use a chronograph for to test your standard deviation or did you just measure your vertical spread?

[foxx]

Honestly, consistent neck tension more then anything. Its pretty much that simple. I know there are a lot of opinions out there. For myself, I use Lapua brass and every lot I have ever trimmed had inconsistent neck thickness. From there its just my education. I was taught by the guys that I shoot with that you just neck resize. Seat your bullet, measure the neck and use a bushing a bit smaller.
So basically I learned that's what to do, Midway and everyone else sells the items needed to do it and the top shooters I personally know told me to do it so it was just what I did. Pretty simple.

Okay, now. THAT makes sense to me. Honestly, so far I have not seen a need to turn the necks. I trust it can be necessary, though. When I do, it will be as you stated here. What didn't quite make sense to me was getting as "little neck tension as possible." That sounded a bit arbitrary to me. Again, please, try different depth and different tensions (if necessary to allow for seating into lands) and report. I would be interested in your results. :)