Yes, I live in the Soviet Socialist Republic of California where mob rules and LE is 'just doing their job'. The Effing Anti's got copper only for all hunting. Now for my truth in advertizing. I love birds of prey. I breed birds of prey. I hunt with birds of prey. I make my living based on birds of prey. I rescue injured and sick bids of prey. The "save the California Condor" crowd is full of bird droppings and they were infiltrated by the anti hunting and anti gun crowd and used. The darned things cost about a billion a piece. They do get lead into their system from lost game. The problem is lost game not saving the Condor. There are circumstances with other birds of prey and non-picked up varmints. As in squirrels shot with lead and left out. More redtailed hawks are killed by this than Condors. However... While I don't like redtails dieing of lead poisoning or any other birds of prey, I'm not willing to make 'laws' the way the Effing Anti's do. Ok, that leaves me with a moral conscience to not use lead as my choice regardless of the law. BTW: My buddy is the same, he eats everything except the pigs which I get and doesn't want his kids getting lead from vaporization or fragments. To that end, I decided to work on some loads for my 'hunting' rifles that were non-lead in addition to the loads I make and sometimes use but are really for my buddy who hunts much more. So... I'm not going to detail the retained energy issue with lower density materials, someone else can. I've learned a few things and would like to hear what you've learned about non-lead loading. 1) Old Muzzle loaders with really slow twist: Shoot sabot bullets about as accurate as throwing a rock. These guns were designed to shoot round ball, there is only one maker of round ball non-lead, ITX at a buck a piece they are really expensive but of course they work. I will probably shoot my Muzzle loader deer at sub 100 yards so I'm not worried about energy, it just has to be enough. 2) Old rifles with slow twist: I have a German made Weatherby 270. It was a ranch rifle for decades and shows it. It has a 12 twist. With the lead ban I decided to play with this guns non-lead loadings to learn. Eventually it will be a 338 Edge but for now... It shoots factory copper 130 less accurate than throwing a rock. Weatherby ammo with 130 Nosler bullets are fine. My buddies new Accumark Wby 270 has a 10 twist, factory copper 130's are OK, my handload 130 TTSX are better. Pigs to +500 yards with one shot. I used JBM http://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi to compare the stability factors of the 2 twist rates, then went through the weight+length combo's for copper and a 12 twist 270Wby until I found one that was more more stable for 12 twist than my buddies load for his 10 twist. 95 grain TTSX that is intended for 6.8SPC worked out well stability wise but there was no load data I could find (I later found some, not much). I used knowledge from here, load websites, lead and of course Quickload to determine what I believed to be a safe loading. I ain't gonna tell you what but it worked. I loaded a proof ladder and headed for the range. Away from everyone else and with notifying the RSO I ran my tests. There were no issues and velocity was so exact from QL that it was difficult to believe. I had desired a load slightly faster than 3500 for the distance, impact velocity and energy level for the intended quarry, feral pigs. Optimal Barrel Timing said my best would be at 3650, QL said my preferred load weight would produce 3666. The closest I could get to 3650. The node in the ladder test produce 3667. So I loaded up 10 of those. 5 for velocity and sighting, 5 for group. The velocity average came it at 3669 for 5 and the group was sub 1/2moa. The gun never shot that well before. Conclusion, lighter copper than you think and faster. New rifles and slow twist: Everything from above applies of course. My 12 twist 223 just can't shoot copper. When I use JBM I can not get a stability for any non-lead bullet and shooting some proved it. New rifles and normal twist: Based on the above and my experience with my 'new' rifles. My 3L 10 twist barrel seem to love copper, FedPrem copper shoots sub moa very nicely for my 300WSM If it doesn't work, drop down in bullet weight and go faster. One last bit before your turn. My buddy is mostly shooting his 300RUM with my loads of 180TTSX now. Pigs are now 1000+, Mule deer was 675 and the Prong Horn was 725. All one shot. My 300RUM hunter is on the way.