This response for posterity for future M-Rodders who have not given up on the best PCP ever
,
! Having gone this thread astray
so trying to get back on track. As has been pointed out by at least one member, nobody is going to do a regulated M-Rod with the stock hammer and spring thus wanting "middle" adjustments of the stock setup is not going to work and is not what is wanted. An SSG is needed.
So, my probably misguided direction would be (for a .22 or a .25):
1. Huma regulator with gage hole and also get the XXL plenum to play with (sometimes sold as the .25 kit)
2. Tim Hill #7 valve poppet spring (lighter than stock)
3. Tim Hill .161 aluminum transfer port or drill out stock (not easy)
* 4. Optional, purchase Tim Hill gage manifold (gives more HP volume than stock)
5. Drill/ream barrel port to .161
* 6. Purchase and install this SSG:
A lightweight SSG for guns regulated 1800psi and under. Regulated guns could still tend to have hammer bounce with traditional spring loaded hammer on valve. The nylon makes cocking the gun smooth with added dampening effects. Hardened faceplate for long sear life and forward weight. None...
www.airgunrevisions.com
7. Remove rubber depinger as no longer needed and uses up a smidge of HP volume
8. Set Huma reg to 1800 psi
9. Shoot rifle over chrono for velocity and adjust free flight hammer gap to increase or decrease velocity and incrementally raise reg pressure up to 2000 psi
*Do these things only after shooting the rifle over the chrono at 1800 to 2000 psi regulator settings and adjusting the SSG to minimum possible gap and still have low velocity. I would work up to .19 TP and barrel porting for a .25 rifle. And at that point for a .25 you might need to open the valve port a little.
Note: install a piece of lock wire around the regulator screw to allow pulling the regulator for adjustment without pulling the gun completely apart.
And back off topic, my unregulated .25 M-Rod side lever with extended AGR hybrid reservoir, Tim Hill valve, AGR steel hammer, .161 TP and barrel porting, Custom Air side lever breech, 9 round magazines, bottle brush depinger. It shoots 27 shots at 52 fpe average or .5 turn in to minimum free flight gap it gives 60 fpe average for 19 shots, both on a flat Bell curve. I love this rifle:
You can do a good shooting M-Rod without messing with a regulator.