Barrel life, 6BR vs 6x47

[65BR]

Estimates?

Thanks.

 

[65BR]

Thanks rewinder,

I don't shoot matches nor prairie dogs,....yet) so usually 3 or 5 shots, cool, and if a sporter bbl it gets 3 usually, saves bbl VOLUME wear, and less heat build up.

Likely would plan on set back to extend life. I'll look for the spreadsheet, thanks again.

 

[Hammerhead]

Here is the spreadsheet.

Hammerhead

 

[Rock63]

Here is the spreadsheet.

Hammerhead

Where should the Psi be acquired for this excel spreadsheet? It is not listed in my Speer manual

 

[TonyR]

I estimate the pressure with QuickLoad.

 

[Octopus]

Where can I find the heat potential for the powder?

 

[TonyR]

I get it from QuickLoad as well, but the version of the spreadsheet I have also has the heat for most powders. I have attached a copy.

 

[Octopus]

Table seems to be close to correct for a 6 BR and a 25 BR but when I ran a 30 BR it went down. Generally in a BR case the barrel life goes up with bullet diameter other things being equal.

A 243 with 30 grs of powder,3,860) & 62,000 psi comes out about 2,991. A few more than I expected but close.

A 25 BR with 30 grs of powder,3,860) & 62,000 psi comes out about 3,097. Seems to be tracking.

A 6.5 BR with 30 grs of powder,3,860) & 62,000 psi comes out about 2,997. Trend line is now down. Not expected.

A BR with 30 grs of powder,3,860) & 62,000 psi comes out about 1,970. Trend line is now down. Not expected.

The 30 BR30 grs of powder,3,860) & 62,000 psi went negative on the rounds count..

???????????

 

[canuck]

If every chamber/barrel, some barrels are tight/loose,some chambers are tight/sloppy) is different how could a computer program possibly predict pressures etc with any degree of accurracy? To me this just doesn't make any sense.
Am I missing something?

 

[TonyR]

Canuck,
Excellent point and I am sure you are absolutely right. I use QuickLoad to save time and money with load development. Whatever its limitations, so far, its muzzle velocity estimates have been within a percent or so of what I see with the chrony and I haven't seen pressure signs if I stay within the pressure limits suggested. But to your point, I also regularly shoot loads I developed on my own that QuickLoad says should be way over the maximum pressure for the case, and I have to believe that that is only possible because my rifle is probably on the good side of enough of these variables you have mentioned. I use the barrel life formula the same way, just as a rough guide and I believe it has saved me from some expensive mistakes.

 

[signut]

So, a 243 with say 38 grain, same heat index, 62,000 psi, will have __________ accurate life in barrel. Please fill in the blank ., looking at a 6 x 47 lapua ).

 

[TonyR]

Signut,
Just running those numbers as you gave them, the formula gives 2152.

Octopus,
The formula does give some weird results for the 30BR. The version I'm using does not go negative but it gives 484 for the barrel life. Hard to know without having all of the details from the spreadsheet which appear to be hidden by the author,not me). What I can say is that I have only used the speadsheet myself with data taken from QuickLoad and I was not able to find a powder with 3860 heat where 30 grains would give me 62000 psi in a 30BR case. I tried 30 grains of H4198 with a Berger 125gr bullet and got 42994psi. Plugging that into the formula gave 697 rounds which still sounds weird. Danny Brooks talks about getting 4000 rounds from one of his 30 cal magnum barrels, so this really makes no sense to me either. What is it they say about lies, d**m lies, and statistics???

 

[Obtunded]

Well, I can tell you from my own experience with the 6X47 Lapua and a Krieger 236 1:8 shooting 105 VLDs at ~3075 over N560 that is was good for about 1500 and it was not competitive anymore.

Since it took hundreds and hundreds of rounds to even find somethng that worked, I was over-all not overly impressed, but I'm a sucker for punishment and I rebarreled in a 7 twist to see if that is any better.

6BR with the same bullets, 3000+

 

[TonyR]

Obtunded,
I have been using N540 with the 105 VLDs in my 6BR and the lands have moved out about .010 in the last 500 rounds. I expect it to make something in the 3000 vicinity as well.

Octopus.
I just noticed the 30BR Cartridge Guide on this website. I tried one of those loads for barrel life. I put 34.7gr of H4198 and a Berger 110 bullet into QuickLoad and got 59243psi, right near the max presure for the case. Plugged these numbers into the barrel life formula and got 2447 rounds. Sounds more reasonable but still on the low side. Seems strange that more powder and more pressure would give a longer life than the last set of values I tried. Beats me. Maybe the person who developed the formula will see this and explain??