Why is 6x47 Lapua a finicky cartridge?

[arm017]

Recent discussions online and in person have started to surface over the past few months about the nature of the 6x47 lapua.

There seems to be a general contention that the 6 x47 lapua is a finicky cartridge which mirrors my experience with it personally.
When I refer to finicky, I am referring to how the load development process seems to be extremely sensitive to powder charge and will have very large jumps in velocity from even .1 grain of powder weighed down to the grain.

So why do you think the 6 x 47 is turning out to be rather moody for not a minority of shooters- when the 6.5 x 47 is regarded as quite the opposite?

 

[Ein]

No clue. Every rifle I know of personally (6 of them) have been simple, wide velocity nodes and easy load development.in fact, there's 1 load that's 1/2 minute in 3 of them.

 

[Geno C.]

Mines been pretty easy to tune. A little less easy than my br but easier than my 243ai which is about where it falls capacity wise

 

[Milo 2.5]

I've had 2 barrels and found it easy to tune. I think there is a tendency to run faster powders, or the same as 6.5 x 47. Smaller hole-slower powder, but that range is limited too. XC case mirrors the x47 really, but that 1 gr more capacity just makes it easier.

 

[arm017]

I've had 2 barrels and found it easy to tune. I think there is a tendency to run faster powders, or the same as 6.5 x 47. Smaller hole-slower powder, but that range is limited too. XC case mirrors the x47 really, but that 1 gr more capacity just makes it easier.

So what type of powder would you recommend?

 

[Milo 2.5]

I ran VV N550 in both my barrels, but most would not because of temp sensitivity issues, which I did not see. IMR 4955 may shine, not as low on the chart as projected. Like I said, limited, but feel some problems self made with faster powders, the usage range shrinks.

 

[Supersubes]

I agree. For whatever reason, it just isn’t nearly as forgiving as the parent case. Four barrels were cut with my reamer, which has a standard dimensioned throat and .104 freebore. The first barrel was finicky(Lilja 3 groove) , and didn’t wake up for hundreds of rounds. It was my personal barrel, and I put about 900 rounds through it on steel and prairie dogs. The second barrel reportedly shot well, but I never had any direct experience with it (bartlein 5r). The third barrel was apparently a dud, although the operator was suspect, as was the treatment of the barrel(bartlein 5r). The owner gave me that barrel in disgust. I had the breech cut off and rechambered to a .243. I put just enough rounds through it to see that it hammered, and sold it. When I was learning to chamber my own barrels, I took my barrel and cut the entire breech off and fit it to my AW. Like the .243 re-chamber of barrel #2, I put just enough rounds through itnto see that is shot really well, and shelved it.

 

[missed]

Compared to a Dasher or BR yeah, but my current 6x47 has been easy.

 

[steve123]

I have a longer freebore than most, .208" originally intended for 115's. I use H4831sc now and have been for the last 3 barrels, either 105's or 115's. I think it's a good idea to keep the bottom of the bearing surface of the bullet above the neck shoulder junction.

In 7 barrels total I've found good loads quickly. The 105 hybrids which I use currently have a huge jump but they shoot great, the 115 DTACS I could reach the lands no problem.

 

[arm017]

I have a longer freebore than most, .208" originally intended for 115's. I use H4831sc now and have been for the last 3 barrels, either 105's or 115's. I think it's a good idea to keep the bottom of the bearing surface of the bullet above the neck shoulder junction.

In 7 barrels total I've found good loads quickly. The 105 hybrids which I use currently have a huge jump but they shoot great, the 115 DTACS I could reach the lands no problem.

Have you found barrel life to be any better using H4831?

 

[arm017]

IS there a preferred powder for the 6x47? Most in the reloading depot are using h4350/ varget which have given me tiny accuracy nodes thus far. I have had a handful of people talk about using RL16 for 6x47.

 

[missed]

I have been running 4451, it's been working well. Temp stability isn't as good as 4350 but it's predictable.

 

[steve123]

Have you found barrel life to be any better using H4831?

Not really, because 3 barrels ago, that one was melonited and went 3000 rounds, so it isn't apples to apples compared to a standard barrel. This one I have now and the one which is on a friends rifle which I sold to him aren't worn out yet. I'm at 1200 rounds now and he's only at 600 rounds.

H4831sc provides good temp stability, near perfect load density, and is easy to find. If you use a lighter load and a shorter barrel with H4831sc, you won't quite gets the speeds of the faster powders but will likely benefit in more barrel life. In my current 28" 8 twist I'm getting blazing speed like 3172 fps with 105 hybrids. It's a warm load but not a hot one and is slightly compressed. That's where it shoots best, square in the high node and the case won't take more powder.

I've found that R-17 and 95 SMK really scream! Experimenting one day the top velocity was 3500+ fps before the bolt hinted at being sticky. I wouldn't try to work up a load up so high but between 3300 and 3400 fps seemed about right when looking for signs of pressure on the brass.