If I had a huge scanner I could scan one and send it to you, but I don't. If you send me a private message with your mailing address I could snail mail you one in a tube though.
There are some 200 yard and 200 meter BR targets near the bottom of this page http://www.6mmbr.com/targets.html that would offer a good challenge at 300 yards. They are in PDF format and have the advantage of being printed off a standard size printer and saved. Put your pointer on the target, click, then print. I recommend using Heavy Card Stock available at OfficeMax or Office Depot. Art