Recent content by nervoustrig

Just FYI the part I referred to as the piston and Scott referred to as the spool is the brass part on the left side of this picture

Nice shooting with irons at 50y! I had pretty much the same experience with the 9.1gr domes vs the 8.4gr. The 9.1gr group nicely from pretty much every .177 rifle in my possession but the 8.4gr only grouped well from a couple of rifles. I’d have to double check but I think the ones I have...

Possibilities that come to mind: Damaged O-ring – When the piston cycles, the O-rings break free momentarily and then have to resettle. If a small bite is taken out of one of the O-rings, it may leak for a short time until the elastomer has some time to cold flow, so to speak, and re-seal...

Pressure creep is caused by surface imperfections in the regulator's valve seat (wear, or damage, or machining marks). Many times it can be fixed by fine wet sanding. Again, there are links in my profile that go into with more depth.

AOA link: https://www.airgunsofarizona.com/precharged-pcp/rainson-draco-walnut/ Mfg's product listing: https://www.rainsonarmory.com/products/14-rainson-darco-w-pcp-airgun.html

I'm pretty minimalist. Cleaning barrels is almost always done with it on the rifle, using a pull-through, the gun either lying on a memory foam pad or in a basic rifle rest. For light bore work such as sweeping felts with J-B back and forth to knock down surface fretting, I simply clamp the...

Yes sir, it's a shopmade lapping fixture. The faceplate has a small amount of adjustment to center up the rod to the barrel to keep it from rubbing:

Hmm, yeah that’s interesting. It seems to point away from potential movement of the barrel or shroud or scope. Unfortunately I don’t have a theory as to how dry firing avoids an initial lateral shift of such a huge magnitude. I’ll definitely keep an eye on the thread for developments or...

Turning down the OD in preparation for threading is likely the biggest challenge. If you have a sufficient level of DIY spirit, you can improvise a crude lathe with a drill or drill press to spin it up and support the muzzle with a bushing. The bushing can be a piece of wood with a hole...

Oh wow, my assumption was we are talking a nuisance shift of a half inch or inch tops. Pretty safe to say 6 to 8 inches is not due to differential material expansion rates or even harmonics. Can’t say that I’ve ever encountered something that severe but the good news is it should make it...

In the world of airguns, cold bore is a blanket term frequently used to encapsulate a variety of subtle factors having little to nothing to do with the actual temperature of the bore. https://www.airgunnation.com/threads/whats-this-about-cold-barrels.1325144 How much is the lateral shift at 25...

Getting the 16.2gr .177 up to useful speeds from such a short barrel will require very high pressure. Probably beyond what the rifle is designed to operate, and why the preset is topping out at 700fps for 15.9gr.

That’s the right idea but it’s easier said than done. If the free end has more than the slightest amount of play, you can try rocking it back and forth to interpolate where the approximate midpoint is. Or you can wrap the rod in 2 places (breech and muzzle) with tape until it is a slip fit so...

Efficiency expressed in units of fpe/ci.

Your markups of plateau and knee are indeed correct.