How is this possible

[Hillbilly delux]

I have been shooting a very accurate Browning x bolt HB 6.5 creedmoor. The 2nd honest factory moa rifle I’ve ever shot above 24 cal. 5 shot groups. I don’t like admitting this because I am anti 6.5 creed and love Remington 700’s. This rifle shot 4 consecutive 5 shot groups sub moa without cleaning. Switch to factory 143gr ammo and 5 shot groups went to 2”. Had to clean barrel every 5 shots to keep it shooting this good. Inside of barrel looked like a chimney.While cleaning noticed outside of barrel was was also black. Chronographed at 2670 average for five shots with my chrony. Sent remaining boxes back to factory for evaluation. Tech support called and said ammo didn’t meet their accuracy specs and they were replacing it. I asked them a few questions about why this ammo was so dirty. He said it was 54,000 psi. They chronographed it at 2680. I forgot to ask for how many shots. My question is if pressure equals velocity how was it this fast.

 

[ismith]

All 6.5 Creed-more shooters have wives who have boyfriends, that's how it was that fast.

 

[EastTNHunter]

Pressure does not equal velocity, there is more to it than that. The goal is for a particular load to get to pressure and maintain that pressure for the appropriate timeframe to net consistent maximum velocity. That is why there are so many different types of powder with different burn rates that produce different pressure curves. Lower pressures can lead to more fouling of the chamber area because the brass casing does not properly expand to the case walls and form the seal quickly enough. Low pressure can also lead to more powder fouling in the barrel because it did not yield the proper pressure for a full burn. But some powders just burn dirty, as well.

 

[Hillbilly delux]

Pressure does not equal velocity, there is more to it than that. The goal is for a particular load to get to pressure and maintain that pressure for the appropriate timeframe to net consistent maximum velocity. That is why there are so many different types of powder with different burn rates that produce different pressure curves. Lower pressures can lead to more fouling of the chamber area because the brass casing does not properly expand to the case walls and form the seal quickly enough. Low pressure can also lead to more powder fouling in the barrel because it did not yield the proper pressure for a full burn. But some powders just burn dirty, as well.

Thanks for the reply especially on the last day of rifle season. I’m a lazy typer. Here is some info I left out in original post. Case necks and shoulders were clean. Only inside of barrel and about 10” of outside of barrel near muzzle were black. Maybe the have to make brass and bullets softer for 6.5 creed so they will still kill half decent at such low velocity. I’ve saw guy get close to that with bolt action 30/30’s. I assumed and you know what that does Factory ammo Used a standard load that had the same powder, bullet and primer. For example federal blue box 130 gr 270 Winchester even different lots have same components. This wasn’t federal ammunition and I’m not posting the company name I don’t want to get anything started like that. I’m in Greene County so I think we might live close.