Velocity will change given all other things being equal based on variations in case capacity. Case capacity, in my experience does vary with manufacturer and sometimes even with cases from the same lots.
When I first started reloading, I tried to get brass from the range. Eventually I found through trial and error that I also had to sort them by MFG. But I never got the accuracy I wanted until I started getting focused on keeping every detail in the reloading process consistent including case manufacturers.
When I first started shooting my 308 I got 200 rounds of factory GMM 168Gr with the intent of reloading the cases. I went to a 1000 yd range and I found out that the 168SMK's couldn't hit the 1000 yd mark due the the boat tail geometry being a bit off according to a reliable source. I started using loading 175 SMKs and Bergers and problem was solved at 1000yds regarding accuracy . My problem with Federal Cases was that at about 5-7 reloads, some of the the primer pockets on the Federal Brass started getting sloppy. I changed to Lapua and never looked back for my 308, and 6.5CM. My reload count with Lapua went way up. I did get some Peterson back for on of my 6.5CM's but that was a while back.
I try to do the load development with components that actually are available which is why I used 4064 instead of Varget for my 308. For the longest time, Varget was just not available.
I realize that what I do might be a bit extreme, but when I have a rifle built, I get enough brass and other components to burn out the barrel based on a reasonably expected round count and brass expected reload counts after I fugure out my go-to load recipe. I keep that brass labeled for that weapon with a card in the ammo box indicating the reload count of the rounds in the box and reload recipe. I probably over bought but I got 500 cases for my 308 and each of my 6.5CMs.
I go through a fairly extensive load development process to get the accuracy I like, and I dont care to mess with going thru the process every time I have to change a component due to availability, so my purchases reflect that desire. Being single I don't have to explain to anyone why the credit card statements have hefty charges to reloading suppliers. I had to question my sanity after I got a few CC monster statements. I get 2 (8lb) jugs of powder at a time and insure they and all my other components are of the same lot as an example. By the way I follow the load development process outlined in the article on the Primal Rights website. No I have no financial interest in the company but I am a happy customer of theirs.
From my perspective, if you can afford it, buying in bulk and insisting on the same MFG lots is the way to go IMO. The problem is now we have some reloading component supply issues that need to be fixed. Getting a straight answer as to what's the cause seems to be a challenge. One thing that is apparent is that someone in the supply chain seized the opportunity to increase prices far in excess of the increases in costs and blame it on inflation.
I still have a bunch of 308 Lapua brass loaded up with 175SMK's, in the box but they're gathering dust as I like shooting my 6.5CMs more.
I realized just how sick I was when I told a friend, who was and still is a casual shooter, that I weighed and sorted my bullets and my cases and boxed them accordingly when I get my bulk purchases in. Still remember that look. Priceless. The thing is, due to current prices I, haven't made a bulk purchase in well over a year in protest of component prices.
Just my .02.
Martino
