I've had a chance to do some more testing, and while I still don't see what the fault is, I think I've narrowed it specifically to the turret seal itself. I took some pictures comparing this clone to the Apeks DST (DST is on right, or top, in all), though of themselves I don't know they show much. I took a number of measurements of the body, turret, and bolt assemblies - lengths, ODs, step distances - and while there are only a couple of differences that exceed a couple thousandth's, they make me think this is a copy, and not an actual rebranded Apeks.
Here are the dimensional differences I could find:
Again, I can't spot any issues with the condition of the o-ring seating surfaces on the copy body or turret, and I've tried more than one fresh 024 o-ring (lightly lubricated). I'll take a second look at dimensions there to see if it looks like a proper gland is being created.
Does anyone think gooping up the gland with grease might help? Haven't tried that yet... I can also see if I can find some slightly oversized cross-section metric o-ring to try. Otherwise, I think I'll be sending this back to the seller. The 2nd stage it came with seems like a decent working adjustable model, though I can't match it to any Apeks models with available information. The adjusting feature works by pushing a spring-loaded piston against the screw-end of an otherwise standard threaded poppet arrangement. I recall seeing a TUSA model that used this approach.
Here are the dimensional differences I could find:
- the boss on the body that the 024 o-ring fits over is about .010 larger OD on the copy than the Apeks
- the copy HP seat (white) is quite a bit longer, though there's no knowing (at least by me) that either seat is the proper part
- the head flange of the turret bolt is significantly thicker on the copy (as is the plastic thrust washer)
- I'm going from week old memory (risky at my age), but I didn't measure any differences in the turrets themselves, other than the inletting for the plastic ring on the copy
- you can swap the entire copy version of the turret bolt and HP seat into the Apeks, and it seals fine, though IP is about 5psi higher.
- if you try the converse, the Apeks turret bolt hits a hard stop the moment the threads engage. I've looked and measured, and I don't see the cause of this
- swapping the Apeks turret onto the copy doesn't fix the leak, and for the life of me I think I swapped the copy turret onto the Apeks, but I don't recall now... damn!
- swapping thrust washers doesn't fix the leak
- with tank pressure of ~100 psi in a nearly empty tank (based on IP reading), the copy still leaks at the turret seam
Again, I can't spot any issues with the condition of the o-ring seating surfaces on the copy body or turret, and I've tried more than one fresh 024 o-ring (lightly lubricated). I'll take a second look at dimensions there to see if it looks like a proper gland is being created.
Does anyone think gooping up the gland with grease might help? Haven't tried that yet... I can also see if I can find some slightly oversized cross-section metric o-ring to try. Otherwise, I think I'll be sending this back to the seller. The 2nd stage it came with seems like a decent working adjustable model, though I can't match it to any Apeks models with available information. The adjusting feature works by pushing a spring-loaded piston against the screw-end of an otherwise standard threaded poppet arrangement. I recall seeing a TUSA model that used this approach.