I want to say you will lose about 35 to 40 fps per inch, not a huge loss at all.

With the 20" tube I'm running, I still get 2900+ with 100 grain bullets and reasonable pressure. Use IMR7828 or MRP.

I have a load with H4350 that goes just over 2800 fps with 100 grain Hornadys, but the deer don't die no slower.

I really like my little .243, and use it a lot out of treestands. The McSwirley I have on it was done in what I intended as a Harley-Davidson theme. My daughter said it looked Hallowweenish and called it "The Great Pumpkin"

The name stuck.

[Linked Image]