Just go to your local hardware store and pick up individual drill bits in sizes 45 through 51. Try them in the current gas port and when you find one that just barely fits in, use the next size larger and so on until you get reliable function. You can always return the bits you don't need. I don't think you can use the HK416 gas port size as a true guide because the Titans don't use the gas rings on their pistons. This isn't rocket science, just go slow and don't enlarge the port too much at a time. But even if you do overdo it, you can switch back to the vented gas block or use a heavier buffer/spring.
Your barrel appears to be between 10.5 and 11" in length (assuming about 1/2" threaded under the flash hider). You don't need the HK piston to get reliable function, you just need a little larger gas port. Henderson Defense in Nevada has run thousands of rounds through their Titan uppers without changing the factory pistons.
Put a couple drops of penetrating oil on each GB Roll pin and drift out either Direction. I have no clue whose DIMS Titan DEF used, but if you swap this it should cycle. I have no clue either wether Titan DEF used the HK Heavy Tungsten filled long buffer and heavy spring? Be careful with this, if your using a short buffer your Carrier key will damage rear of lower receiver when it smacks it.
The GB swap should fix Short Stroking IF they used HK DIMS for Gas Port Hole.
I would set it up exactly like a 416/MR556 as I have to believe they copied DIMS to keep costs at a minimum!!
Doesn't matter if barrel is 10.5" or 11", if bbl gas Port is still in location (+/- 1") it shouldn't make a bit of difference.
If you Have a suppressor, it should also cycle!!
Last edited by JNAP94; 08-31-2017 at 09:28 PM.
Just so you know, I bought a couple of Titan 14.4" uppers from Todd. I asked him about buying a 16" upper and shortening it to 10.5" and open up the gas port. He said that wouldn't work. He said the 10" Titan uppers actually had a smaller gas port in the 10" barrel than the 14.4" or 16" barrels. He said that the gas blocks are different. I would also recommend changing the extractor spring. The two 14.4" and two 10" Titan uppers plus the recent GSG-9 copy of the 416 10.4" upper all had weak extractor springs.
This one started out as a 16" with vented GB and now has non vented. Would be nice to have the correct parts to try out so I know what to buy.
Last edited by 1Copper; 08-31-2017 at 11:32 PM.