6.5x284 Norma Vs. Winchester
What is the difference, if any, between a 6.5x284 norma and 6.5x284 winchester? will the brass interchange after fire forming? what brass is available for each? Is the load data interchangeable? What is most popular in F-class and why?
The Norma is a touch longer in the body lenght
Keep in mind the Norma has been accepted by SAAMI/CIP and there is a set std. I don`t believe the same exists for the Winchester version.
The Norma delivers slightly greater velocity as well, due to the greater volume.
Beware that some manuals use the Winchester/Hornady version (Sierra) and other manuals show Norma data (Nosler) and there can be a BIG difference in maximum powder charges listed.
There are a couple major differences between the cases.
1) The Winchester is a .284 Winchester and has to be necked down to 6.5mm.
2) The Winchester is smaller than the Norma or Lapua brass in the critical area of the case head. The rim diameter is the same, but the case 0.2” forward of the rim is smaller.
If your barrel is chambered with a reamer designed for the Winchester case you most likely will have trouble with the bigger Norma and Lapua cases fitting in. Conversely if you use a reamer designed for the Norma case, your Winchester cases will expand in that area. This may contribute to primer pocket expansion.
You should decide which case you are going to use and have a competent riflesmith choose the reamer. Loads should be very similar. Most F-Class shooters using a 6.5-284 use Lapua brass, but a number of top shooters including Team Berger use Norma.