I do the exact same thing to my brass each reload so I know that wouldn’t be a factor , I trim , shoulder bump, clean and anneal each time. The load stays at a low ES and SD but it started at 2970 FPS and 3 times reloaded it’s now at 3025. I don’t understand why.
Search
Same load is getting higher and higher in velocity each time the brass is reloaded.
Same load is getting higher and higher in velocity each time the brass is reloaded.
I agree with reloading all day, I've spoken to some bullet manufactures on this subject and deal with this situation myself. My tests I've done so far included settled powder in case vs shaking the powder prior to firing showed a significant change in muzzle velocity. Shaken powder showed a drop of about 60fps on average but a massive settling of my SD. Settled powder rose from my "standard MV" and velocities increased throwing out my SD. But so many factors change, how much copper in the bore will drastically increase your MV, different lots #s of powder, bullets, and primers change this, brass hardness, donuts in the case neck/shoulder junction, improper neck thickness, weather changes in temperature vs burn rates. With many other factors as well. Your best bet is to start measuring everything, chart it out and then look for discreptencies. I think because of all these variables so many people cannot give the right answer without all the facts, we as reloaders can only give factors which showed to most change which was temperature.in my experience a compressed load gave less variance because I didn't have to shake each round every time. A sniper taught me that one. Sniper 101 has very good insight on the things that change your velocities and learning the subject could help you isolate variables. Good luck man.
Temperature spikes due to weather. It’s not uncommon. Even a couple of degrees difference can make an impact.
It’s been 30F degrees outside everyday and I made sure my ammo was covered from the sun when I shot it and I’m using h1000 which is suppose to be temperature stable. So i think it’d have to be a decent temp difference to cause 60fps spread. I think it could be the barrel isnt quite broken in or something like that so I clean just fully cleaned it and going to shoot it again and watch for the velocity to zero out
Barrel could be the problem. Even with temp stable powders you will see a little bit a FPS spike. Checkout Varget vs precision. Both super temp stable and you should see the difference between 30 degrees and 100 degrees. Regardless, this could be a mixture of problems here. Moreover, leaving your rounds inside the chamber from a warm barrel will heat up the next round that’s being fired. Transporting ammo from a warm car to outside in the elements will have an effect too. Like I said, lots of scenarios here.
What sucks is that finding out what variable(s) is/are causing it will cost components. If you have some of the same brass, and your theory is that it’s reloading it which is causing the increase, load up a batch like normal and take virgin brass and load them the exact same way. Store, transport, shoot them on the same day same gun etc. If that confirms it, then at least you know. I had subsonic loads that wouldn’t cycle my DI gun. I had a lighter charge weight that was in my pocket instead of on the ground. It was 45F outside. The lighter charge weight cycled my gun because they were in my pocket, not on the ground. The next time I went out, it was 60F. I left both outside for a while and they both cycled just fine. Now cycling gas operateds isn’t the same as velocity spreads, but the point being seemingly small temp changes and shortage/ambient temp can make quite a difference.