better to ask than do something dumb

[Bassfish1952]

Yes the lead cup/core bullets shed metal (mostly lead) as they enter and pass through the deer, so you might indeed be finding some of that.  Much of that can be eliminated by the processing post-mortem.  And a lead free would not present that issue for you.
I know some guys on here might not answer this way but have you thought about maybe a 6mm creedmoor? very controllable, still 6mm and the lead-free you can get higher velocities with the larger case size... or the 6.5 creedmoor, for that one I'm currently loading up some barnes 115 gr all coppers.  Using a 20" barrel this one has your 300 yd reach with retaining enough knock down at that yardage.  I'm loading for 2850 fps MV.  The 115 is the newer barnes design with the lower opening threshold, but even so I don't plan on using it much below 2200.  It does keep 1000 ke out to 400 yds however.
And I have some Trex 110's (BC of .420) in the 6.5, just haven't had the chance yet to try them out.
Cavity back says their design will open down to ~1500 fps.  But 6.5 again, just sayin'.

Like Larry potterfield says, a guy always needs "just one more" rifle... lol!

Thanks for the reply
I have a cz557 in 6.5 CM It is what I used this year for my hunting.With the 120gr CX But back when I weighted 400lbs and had promised my grandson I would take him deer hunting I bought a cz527 in 7.62x39 because it was very light and a min for me to kill a deer (I thought). Now at 200lbs with more energy I took my grandson this year and had a great time with the 6.5 CM BUT I had this cz527 sitting in the gun safe. Thought about selling it but after seeing the 6.5 Grendel and the 6mm arc I decided to rebarrel it to 6mm ARC
The 7.62x39 was below 1000 ft/lb at about 150yds
My understanding is the 6mm ARC103gr eldx  will have 1197ft/lb at 300yds so I am good there. I bought a 24" barrel and Hornady's test info is out of a 24" barrel so I should be close with their 103gr eldx round for hunting but if I could get close to the same energy at 300 with a CX bullet that would allow me to use in California and not have lead in my food. I am happy with the 103eldx and have already bought some to break in the new barrel when I get it and will use it if I do not find something better or try my hand at reloading. 
Right now I take my grandson up to Alabama for deer and it looks like I will until I am to old to get out of the truck, but we have people in California and may hunt there too. I can always use the 6.5 CM BUT  that little cz527 keeps calling my name.

Again thanks for the reply, I saw this forum and am just now learning all I don't know