I've turned about 50-75 bullet pens in deer antler. I use 15 minute epoxy for gluing tubes. I've had several come loose on me with CA and frankly I find epoxy easier to work with on tube glue ups.
For drilling, this is the process I follow:
I first examine the piece around all sides using the brass tube next to it to try to find the best angle through the piece that I think would provide the most color contrast and also leave enough material for the pen barrel. You generally don't want to just go straight through the center of the bone - especially on a really thick piece, because it will usually just turn out pretty white. If you want coloration and character variance through the blank, try to position the pen tube through the piece in such a way that it leaves as much of the outer layers on the pen as possible without making it so you don't have enough material in the middle to keep a round shape.
Once I determine how I want the tube through the piece, I use a sharpie and draw rough guidelines on the antler perpendicular to each end of the pen tube (I'm holding the pen tube at my desired angle on the side of the piece with one hand and just drawing lines on either end of the pen tube with the other).
I then cut the piece along those guidelines leaving two somewhat parallel ends to the piece.
I then place the piece on the lathe between a 60 degree dead center in the headstock and a 60 degree live center in the tail stock. I only apply enough pressure between centers to allow the piece to rotate on the lathe.
Once rotating between centers, you will be able to see a "ghost image" of the blank and judge it's thickness across the entire blank. I view it from above and from the side both while spinning and if it is too skinny in the middle, I back off the live center and adjust the center points until I get a "ghost image" that is thick enough.
Once I have that established, I crank down on the tail stock just enough so that I can start turning the blank.
I use a square carbide tool with a slight radius and try to get the lathe speed as fast as possible and take light cuts until I get the blank as round as possible. It doesn't have to be completely round at this point, but it helps.
NOTE: All I'm doing at this stage is establishing a straight blank that I can safely drill on the lathe without blowing through the side of the antler piece. So you don't really have to turn the piece round much more than a short section of one end if you want for your 4-jaw chuck to hold on to. I just usually go ahead and turn the whole blank down as much as I can at this point since I'm already there.
Once turned, I place one end in my 4 jaw chuck. I use spigot jaws. I use the tailstock live center cone to hold the piece center while I tighten the chuck jaws.
Then I replace the live center with my jacobs chuck and drill the blank with the appropriate bit at a VERY SLOW SPEED!!!
You will fine that some pieces will drill extremely easily and others will drill very hard. I use the absolute slowest speed my lathe will go to (whatever that is on a delta 46-460) and advance the bit no more than 1/2 inch at a time before extracting it and cleaning it. I use an old tooth brush to clean out the drill bit each time I extract it. That's basically because even at such a slow speed, it will still be pretty hot to touch sometimes and also, I've cut my fingers before just trying to clean the antler from the bit.
I've found that using this practice, I can get close to 100% success rate on creating usable pen blanks without cracking, splitting or drilling through the side of the antler piece.
From this point, it's just like any other pen blank. Epoxy the tube in. Square the ends with a pen mill then turn to shape. I turn between centers.
I then remove the bushings and put the blank back between centers (apply the minimum tail stock pressure possible at this point as your applying direct pressure on the end of your brass tube).
I sand mine dry with the pen turning sandpaper kit available everywhere (the cardboard box with 5 rolls in it). I go through all 5 grits. I sand both directions - fwd and rev - with each grit. Then I clean with DNA. Then I apply 2 coats of thin CA then 5-6 coats of medium CA. I use aerosol accelerator VERY LIGHTLY between CA coats. In other words, I hold the can about 2 feet away from the spinning blank and spray once L->R and then once back R->L. That's it.
(btw, I am running my dust collection with the hose immediately behind the spinning piece throughout all of the sanding and CA application steps. I also where a dust mask)
Then I dry sand the CA with 400 abranet until all glossy spots are removed. Wipe the dust off and then wet sand with MM pads through all 9 grades in both directions for each grade.
When finished, I apply plastic polish once or twice.
Then I buff with the two step buffer system. First wheel is polished with the blue compound and the second wheel is just the plain cotton wheel. I use the one I think PSI sells with a #2MT mandrel.
I generally get a very deep high gloss and scratch free finish using this method.
I have recently began experimenting with the walnut oil based finishing technique on antler (Doctor's Walnut Oil and Pens Plus finish). Mike's (MikesPenTurningZ) process is what I've used and so far I'm pretty happy with the finish I'm getting. I have a couple test pens out there to see how the finish holds up to daily use. I can tell you that while not as glossy as CA, the Pens Plus finish, even on antler, is pretty shiny (I'd say semi-gloss +). However, the key difference between the two is that with the Pens Plus finish, the antler still "feels" like antler. The imperfections and character of the turned blank are still there and frankly I'm kind of partial to that look in the end. CA leaves a stunning looking piece, but it feels like plastic (because it basically is at that point).
My only real concern is how well it will hold up and that's what the test pens are for.
So that's my process. I'm not in any way suggesting my way is "the right" way. It may not be "correct" in some people's eyes but it has worked for me so far and I thought I'd pass it on .
Kevin
