6.5 PRC barrel speed up

[Cavila99]

Still fairly new to load development and new barrels but what can i expect for an average barrel speed up after 100-200 rounds and going from virgin brass to once fired?

Running ADG brass, 210m primers, 56 gr of N565 and Berger 156 EOLs out of a 22in HCA barrel.

 

[Harvey_NW]

I do "load development" on new barrels with new components and have had no issues, but I've still yet to have a barrel speed up while shooting a controlled and known load. What I have observed repeatedly is velocity and pressure increase on formed brass vs new. I'm shooting a very similar load of 56.5gr N565 with a 143 out of ADG brass as well. On new brass I was able to load 58gr with no pressure signs at all, once formed and shoulders bumped .002" 58gr had some bolt lift, so I dropped to 56.5gr to make it easy to remember and be safe. This is in a Tikka action which can show pressure signs sooner than other aftermarket actions so your results may be different.

 

[Cavila99]

I do "load development" on new barrels with new components and have had no issues, but I've still yet to have a barrel speed up while shooting a controlled and known load. What I have observed repeatedly is velocity and pressure increase on formed brass vs new. I'm shooting a very similar load of 56.5gr N565 with a 143 out of ADG brass as well. On new brass I was able to load 58gr with no pressure signs at all, once formed and shoulders bumped .002" 58gr had some bolt lift, so I dropped to 56.5gr to make it easy to remember and be safe. This is in a Tikka action which can show pressure signs sooner than other aftermarket actions so your results may be different.

Great info! How much are you seeing it speed up with formed brass?

 

[Harvey_NW]

Great info! How much are you seeing it speed up with formed brass?

To be honest by the time I was shooting formed brass in that rifle I was also doing some cold weather testing and not tracking the velocity differences based on the brass changes.

I think it could be a tolerance variability thing, where if you have a chamber on the min spec side and brass that's close to chamber dimensions, you might not see much, or any change. But in the opposite, if the brass grows a fair bit to form to the chamber, second firing may have more pressure as less energy is being consumed by expanding the brass to the chamber walls. This is just my theory based on my experiences.

 

[Cavila99]

Makes sense, Thanks for the info!