Thanks for all the nice comments guys.
When I picked up this elk shed that I had lying around it just felt too perfect in hand not to make it into a riser. After cutting it to the length I wanted, I started doing a little searching online for takedown angles and ended up deciding on 7 degrees bc I wasn't going to put recurved limbs on.
I marked the angles I wanted to cut on to the wide face of a 2x6 and then fabbed up a clamping system with 2 pieces of scrap wood with V's cut in them and some long bolts, to clamp the elk riser to the 2x6 and still have a nice flat bottom to the other wide side of the 2x6 (Let me know it know if that doesn't make sense). I then used a buddies sliding chop saw set at 7 degrees to cut the angled portions where the limbs would be seated. By doing it this way I was making sure each cut was in the same "plane" and not introducing any limb twist compared to the other limb.
As far as securing the limbs, I had my doubts about the screw-in inserts and if they would pull out under that much tension and the fact that they would be screwed into mostly the porous inner portion of the antler. I opted to drill through from the back of the riser and use T-nuts instead, thinking that option might be stronger (maybe it would've been fine the other way also IDK). I held the limb where I wanted to mount it and drilled a small pilot hole through the limb and riser. I then went back and widened the hole through the limb to fit a bronze sleeve in it and widened the hole from the belly side of the riser to slide the T nut in. I then measured out and drilled a hole further toward the end of the riser to insert a steel pin (1/4" dia) to keep the limb from moving side to side (these holes only go into the riser and limb about 1/4 inch) . Also did this on the limb and inserted an aluminum sleeve into the limb for the pin to slide into. Glued the pin into the riser.
After test fitting all of that, I wanted to strengthen the porous portions of the antler, so I coated it with a low viscosity casting resin that really soaked into the antler well in those porous parts.
I then put it all together. Obviously I now had two deep holes in the riser from the Belly side where each limb bolt went through the t-nuts. From the backside, I put a VERY thin layer of clay around the exposed bolt and filled the holes with the same casting resin. After it was all dry, I removed the limb bolts and was able to scrape out the dried clay from the "back" side.
I am at the point now where I have to decide what I want to do with the two circles of casting resin that are exposed on the belly side. I can either blend them in with the antler (have experience with a little taxidermy work doing this) or fill them with Osage saw dust or some other material and super glue as little accent pieces, maybe even make them into more interesting shapes then just circles.
That is where I'm at now. Like I said earlier, I am still debating skins or not and what type of finish for the limbs.
Forgot to mention before that it has a small shelf filed in to the riser with sheared beaver for a rest liner.
Also added a very thin piece of leather between the limbs and the riser as a dampener/cushion. Got that idea from a post on takedowns here on PA (bubby's bow I believe).
