romad7 75 Posted April 18, 2012 Report Share Posted April 18, 2012 (edited) Here is my very first gun project ever so I didn't want post this until I had it back together and running so here it is. There are still some things that need to be done so it is only mostly complete right now. To start I'll answer some questions that I am sure will come up. Most of my knowledge was gained from reading the forums here and specifically the SBS Technical thread in the NFA section since this will be an 11" SBS when I get my approval. Yes, those are holes in the barrel and no I won't tell what they are for, I don't want to say anything until I have that part complete since there are already some mistakes that need correcting;-) I moved the gas system back 3.75" and can proudly say that it runs similar to before I did the mods. Still needs some tuning, the holes start at a little over 7 1/4". I kept as close as I could to the specs of an 8" gun since that is a tried and true design. Hoping that the extra 3" of barrel (after cutting to 11") will make up for the holes in regards to the requirements of S12 Gas Dynamics (should be a college course). Still need to weld holes, back plate, paint, finish making hand guard, etc... DISCLAIMER: This is NOT easy!!! If you don't have a lathe, you cannot do this. I have no experience in gunsmithing but years of experience in many of the skills/traits needed for this job. If you read the SBS Technical forum and it is confusing to you then pause and seriously re-consider what you are doing before you screw up your gun (there were some close calls for me). For those of you who have the skill but just need pictures, here is the perspective of a fellow skilled noob. Hopefully this helps someone. Here are the pics : Here is where I bored out the gas block to fit the shortened gas piston rod (technically the bolt carrier but it is the piston rod as well now). Dremel sanding drum works well for this. Now it fits, I cut the piston rod a little long to allow for the fitting process later. A simple pipe cutter for the gas tube. Now I turned the barrel down (this is a friend of mine with a shop since I don't have a lathe) If you can, I highly recommend securing the spinning end somehow or you may end up with chatter marks (see next pic). We weren't able to do that and I didn't want to take out the barrel. Her are the new holes. They are .083". I used a hand drill instead of a mill or drill press due to the movements needed to keep the bit from just bending away from the hole. I am sure the better builders have more refined techniques but not me. I drilled straight to start and angled it as it went deeper, it wants to plow at an angle so had to be careful about that. The hole in the gas block is a little bigger now to allow more exposure of the holes. I just drilled it the same size as the hole on the bottom of the block Test fitting. Notice the tape, I put that on the old holes and rubbed a crayon on it to get the impressions to transfer the locations to get the general spacing right. Its hard to see but the gap between the carrier and the trunnion (bottom of gun in picture) is what I used to check the piston rod (carrier end) length Edited April 19, 2012 by romad7 3 Quote Link to post Share on other sites
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