6mm slr

[dannywayoflife]

So would you agree then Dave that the 6slr will give better barrel life than it's parent the 243?

[baldie]

Yes.

[DaveT]

That was one of the factors that drew me to 6mm SLR ....in addition the Boron coating promises longer life ....but God Knows how you quantify that empirically....I must get a Borescope!

[gbal]

Dave,thank you a possible explanation-but enough to explain the considerable ly longer barrel life claimed?we've had sub 2000 to 4000 rounds.

 

I'm still a bit puzzled though-is this a version of 'turbulence' theory,which seems........ errr 'speculative'.

 

Whether it is or not,gases must rise pretty fast up the case,some straightout,some will hit the shoulders,whatever the angle is-I can see the 31 degree shoulder might slow them a tad,and produce some 'turbulence' generally,but these still very hot gases must exit pretty pronto,and contact the throat?

So can this really reduce firecracking/etc quite so much-I suppose maybe,if there is a somewhat critical temperature zone?

The alternate test would be that we wold expect similar % life extension in other 'improved' similarly (31 degree) cases-do we get it.

Other than many rifle barrel experiences, how to measure ?...but then we can't really measure pressure either: I suspect a means of doing so would reduce loads often used,but above pressures,unknown,but somewhat disguised by a small prime pocket.

 

Interesting though,that a small case change might be so beneficial-PPC did it for accuracy (though not by 100% -the 222 was prettty good !)

 

gbal

[DaveT]

As I said...damned hard to measure .....for me its simply an interesting experiment.....but in any case the rifle Dave built me shoots a treat!

[Shuggy]

Gbal, the answer appears to be that the shorter 6mm cases have to use faster, hotter powders, so they wear barrels faster. It is supposed to be the combination of 30/31 degree case necks, plus the cooler powders that achieves the long barrel life.

 

Whatever the reason, there are plenty of people saying that it works. Some people also recommend polishing the throats with bore paste every couple of hundred rounds.

 

I agree, it would be fun to try something a little bit different.

[baldie]

The theory George, is the point of intersection of the gases. Its long been thought that its this that torches throats, as its not only very hot, but add the turbulence effect and its real nasty. If it can be contained inside the case, then so much the better. The ackleys have proved this over the years with better barrel life than their parent cases.

 

The real point to the SLR though, is its long neck.

 

6mmBr , .222 , 6.5 x 47 , 6ppc .......all stupidly accurate cartridges that a muppet can reload with literally anything and make accurate.

 

They all have one common factor.....that long neck.

 

I have a 6slr but it never comes out of the cabinet, its fired around 200 rounds. Its one of half a dozen safe queens that I should really sell.

[gbal]

Ah,thanks Dave...(apart from confirming that by loading those 222,BR and PPC cases quite well,I am qualifying as a muppet :-) , I'm beginning to see something in the turbulence-though the Ackleys don't double barrel life-but let's accept improved life,rather than the more extreme claims,as yet.

Hot gases blasting straight up the central part of the case blow off through the barrel,normal shoulders sort of angle them like a blowtorch onto the barrel,and 31 degrees is enough to circumbobulate them and swirl around the neck for much reduced blowtorch damage.Well,it'll do for me,for now-or until some bright spark really gets in there and susses it fully.If it helps,pragmatically,it's well worth considering.

BIgger cases so therefore enough slower burn/cooler powder not to compromise velocity seems fine too,and together might just do it.

Good point about the Ackleys-sort of fits-no wonder not many fire form 500+cases though!

g