On all the sleds/bolts I've made I used this:
1. Cut the body using joshes specs
2. Make a bolt blank (Diameter, air passages, but no bolt pin hole, or detent hole. And leave the bolt a litle long in the back)
3. Measure the spacing between the bolt in the bore, and lower tube
4. Make a beefy sled thats the thickness I got from "3." and wraps the tube of the body
5. Then I measure the back of the top tube, to the start of the slot (Should be .250" if you are using Joshes specs) then add half of the pill-pin diameter plus about .020" so the pin isn't slamming into the front of the slot.
6. With the size I got from "5." I drill the pull pin hole in the sled
7. Next I stick the bolt in the tube and looking down the front of the body I line the bolt up where I want it to end. I like about a 1/8" before where the barrel threads start. After I do that I cut a tiny scribe mark on the bolt where it ends with the back of the tube. Then from that scribe mark I add another mark thats the distance I got from "5." back. Thats where I drill the hole in the bolt for the pull-pin (Note: Make sure the pull-pin hole is lined up with the air passage. If you want, you can wait and drill them both at the same time).
8. Next I put the detent in the bolt, and cut it to proper length.
9. Next I drill the hole in the sled. Unlike most who make the sled around the pump arm, I do it the other way around. Reason being that in most cases you only end up with about .030" of wall space around the pump arm hle. Thats not enough IMO.
10. Now that the sled is ready, I cut all extra meat off.
11. Now I have to make the pump arm. If this is a cocker, and you drill the sled hole in the right place, all you need is a straight rod. The internal threads for the ram are 6-32, and the sled should be 10-32 if thats what you use. To get the length, with the ram, and sled all the way forward, measure the distance between them. Then add about 5/8" to that for the sled threads, and about a 1/2" for the ram threads. When threading for the ram, over thread that as much as you can as this will be where you are getting all your adjustment from.
11B. If you are doing a rod for a sniper, you'll need male 10-32 threads on both ends. With the pump arm resting in the forward position, and the sled all the way forward measure the distance. Then add 5/8" for the sled, and with a depth gauge (A stick, and your finger nail works) figure out how deep the hole is. Add those three numbers together and you have the length you need. On a sniper you will most likely need to put a slight bend in it. In this case I'd thread the pump handle end first, bend it (with heat), screw it in, measure the distance to the sled, mark it, cut it (making sure to leave the extra 5/8" for threads), then thread it.
http://i13.photobucket.com/albums/a2...r/100_4201.jpg http://i13.photobucket.com/albums/a2...r/100_4175.jpg http://i13.photobucket.com/albums/a2...r/100_4202.jpg
Hope that made sense. forgive any grammar errors!
Edit,
Forgot. For the pull pin I use timmy pins. Though a stainless, brass, or aluminum one could be made very easy.