Anyone do any experimenting with these two shafts or actually measure the spine of each? I'm shooting 400's in both. I just bought some of the MFX's and I'm needing a much longer shaft vs. the FMJ's to get them to bareshaft. I know they are just a touch larger in diameter but I'm talking a 29.25" arrow vs. full length shaft with same amount of weight up front.
I don't know, I've never been a quarter inch different on 340s, 400s, or 500 when setting up with both those same shafts whether it has been my bow or helping friends tune.
Now, I should clarify and say FMJs and MFX Classics with the wood grain finish.
I have a Stalker Tracker longbow that likes the 400 spine. They both spine out the same on my spine tester and the FMJ's and MFX shoot the same for me at the same length with the same weight heads....29" and 200 grains up front. I have no idea why they would shoot differently for you.