Question on Powder Burn rate and Brass Life

[Jet]

Question here regarding 6 Dasher brass life using different powders. Specifically, H4895 vs the other common Dasher powders. With all things being equal other than powder type; velocity (3020fps), brass life, primer, bullets, etc I get clickers when using H4895 at around the 6-8 times fired. With Varget and R15 the brass seems to last forever.

Is this due to H4895 having a faster burn rate than the others which causes more of the powder being burned in the case vs in the barrel?

I understand the small base die resizing aspect to keep the brass working, just trying to understand why this occurs.

Good Shooting and Happy Thanksgiving to all.

Rich

 

[dmoran]

Rich -
Simply as I know it, reason being the H4895 is a higher pressure load.
This is a reason I run longer barrels then many do, so that I can achieve higher velocity levels from lesser powder charges, hence less pressure, to get more brass life. Typically I am few tenths lighter on my charges to achieve equal velocity then others are on shorter barrels. 30 to 31" has been my finished lengths to all my 6Dasher barrels for several years.
Donovan

 

[RonAKA]

To get the same velocity out of the faster burn rate H4895 compared to Varget or RL15 you would need more pressure. So, you may be running significantly over pressure with the H4895. A compressed load of H4350 may allow you to get the same velocity with less pressure than Varget or RL15.

 

[Jet]

To get the same velocity out of the faster burn rate H4895 compared to Varget or RL15 you would need more pressure. So, you may be running significantly over pressure with the H4895. A compressed load of H4350 may allow you to get the same velocity with less pressure than Varget or RL15.

Thanks for the info Ron but I've never experienced any of the typical signs of loads getting hot when shooting H4895 in my match loads. When testing new barrels or components I always run the charges up to see where the pressures start then I back down and stay below that when testing new loads. R16 is my current powder to test and I expect brass will last a very long time with this powder since you likely can't get enough of it in a Dasher to cause pressure issues.

Rich

 

[LCazador]

Case life is all about how hard you stand on the brass. There are other issues such as case stretching that come into the picture as well. So proper die set and shoulder bump also come into the pic. Small base dies can overwork the brass!

 

[dkhunt14]

Jet what free bore are you Running? Matt

 

[Jet]

.135

 

[RonAKA]

Thanks for the info Ron but I've never experienced any of the typical signs of loads getting hot when shooting H4895 in my match loads. When testing new barrels or components I always run the charges up to see where the pressures start then I back down and stay below that when testing new loads. R16 is my current powder to test and I expect brass will last a very long time with this powder since you likely can't get enough of it in a Dasher to cause pressure issues.

Regardless, I suspect if you get your loads checked in QuickLoad you will find that for the same muzzle velocity, the pressure is likely to be higher with the faster H4895, than the slower H4350.

 

[dkhunt14]

Regardless, I suspect if you get your loads checked in QuickLoad you will find that for the same muzzle velocity, the pressure is likely to be higher with the faster H4895, than the slower H4350.

I always thought pressure made velocity. Matt

 

[John Russell]

I always thought pressure made velocity. Matt

Pressure x time makes velocity. You can get 50,000 psi with 12 grains of BullsEye in a 243 with a 60 grain bullet... and have ~ 1300 fps velocity.

 

[Webster]

Question here regarding 6 Dasher brass life using different powders. Specifically, H4895 vs the other common Dasher powders. With all things being equal other than powder type; velocity (3020fps), brass life, primer, bullets, etc I get clickers when using H4895 at around the 6-8 times fired. With Varget and R15 the brass seems to last forever.

Is this due to H4895 having a faster burn rate than the others which causes more of the powder being burned in the case vs in the barrel?

I understand the small base die resizing aspect to keep the brass working, just trying to understand why this occurs.

Good Shooting and Happy Thanksgiving to all.

Rich

I don't think it's possible for the peak pressure to occur when the bullet is still in the neck based on published time pressure curves. I think it was VarmintAl that said when the bullet touched the rifling the pressure was about 8000 PSI. In any case if the peak pressure would occur with the bullet in the neck or in the barrel the case see's the same pressure. The case and tube are both part of the one volume the gas expands into.