Neverending. I shoot with a few guys who have been shooting for 35yrs longer than I've been on this planet and I still hear them mumble "Wait, what? WHY??" occasionally.
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Tuning Is the HW97 Vortek pg4 HO kit a little for spicy for .177?
- Thread starter luckybuckeye
- Start date
Dont know if you gain anything from this on there found sweet spot for .177 , but i kinda agree on that 850-900 fps in one .
https://hardairmagazine.com/buyers-guides/ham-recommendations-most-accurate-177-caliber-pellets/
I also think for me is a 8ish grain ( i mostly shoot 7.9 cphp). Also some heaver pellets can be as fast or faster then a lighter one .. pellets are crazy youd think this pellet will do this or that vs another and it dont...lol
https://hardairmagazine.com/buyers-guides/ham-recommendations-most-accurate-177-caliber-pellets/
I also think for me is a 8ish grain ( i mostly shoot 7.9 cphp). Also some heaver pellets can be as fast or faster then a lighter one .. pellets are crazy youd think this pellet will do this or that vs another and it dont...lol
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I have one of those beautiful, or ugly blue laminate 97's depending on your preference. I dig it. Recently opened up, cleaned, polished, and Vortek HO kit installed. Have others shooting 10-12fpe and wanted to keep this one lively. It is still settling in, but 15fpe is the median depending on pellets. Deadly accurate, very well behaved. Doesn't get much better than this. 
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Nice scope! I have the same on my HW50...I also kept my HW97K with a PG4 HO at full power and it's shooting 8.64 grain FTT at 865 fps...LASER
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one reason the spring is more power is it takes higher speed air to send a .177 pellet through the tiny bore than it does to send a .22 or .25 in a larger bore
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Part of the explanation for reduced efficiency with heavier pellets is piston bounce. Heavier pellets release later in the shot cycle causing the pressure to be too high near the end of the stroke causing the piston to bounce off the cushion of air. This is wasted energy and for a fraction of a second causes a drop in pressure.
Most springers are optimized via spring stiffness, piston weight, and size of transfer port to avoid piston bounce with mid-weight pellets. If the spring is too strong and your pellet too light you will get piston slam and piston bounce when the pellets are too heavy.
Some folks increase the size of the transfer port, others reduce the piston weight and utilize lighter pellets with less powerful springs. Pick your poison
-Marty
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Thanks Marty, that makes sense. Guess I'll stick with pellets in the low 7 grain range.Part of the explanation for reduced efficiency with heavier pellets is piston bounce. Heavier pellets release later in the shot cycle causing the pressure to be too high near the end of the stroke causing the piston to bounce off the cushion of air. This is wasted energy and for a fraction of a second causes a drop in pressure.
Most springers are optimized via spring stiffness, piston weight, and size of transfer port to avoid piston bounce with mid-weight pellets. If the spring is too strong and your pellet too light you will get piston slam and piston bounce when the pellets are too heavy.
Some folks increase the size of the transfer port, others reduce the piston weight and utilize lighter pellets with less powerful springs. Pick your poison
-Marty
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I'd caution anyone about messing with transfer ports. It's hard to predict the affects of increasing the transfer port and it's harder to return them to their original size. Very often increasing TP size decreases velocity because it increases lost volume. Lost volume is the amount of swept volume not used to propel the pellet.Part of the explanation for reduced efficiency with heavier pellets is piston bounce. Heavier pellets release later in the shot cycle causing the pressure to be too high near the end of the stroke causing the piston to bounce off the cushion of air. This is wasted energy and for a fraction of a second causes a drop in pressure.
Most springers are optimized via spring stiffness, piston weight, and size of transfer port to avoid piston bounce with mid-weight pellets. If the spring is too strong and your pellet too light you will get piston slam and piston bounce when the pellets are too heavy.
Some folks increase the size of the transfer port, others reduce the piston weight and utilize lighter pellets with less powerful springs. Pick your poison
-Marty
Increasing TP size can uncork guns and make them less prone to bounce but it can also make them more prone to slam. It's a very dicey thing to play with that's hard to undo.
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This makes me wonder why nobody has made a spring gun with swappable transfer ports to make it easier to tune to a specific pellet/harmonic. Maybe I should have patented that before posting.
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Decades ago Tom Gaylord had a R1 custom machined to have adjustable transfer port sizes. I don't believe he found any appreciable gains.This makes me wonder why nobody has made a spring gun with swappable transfer ports to make it easier to tune to a specific pellet/harmonic. Maybe I should have patented that before posting.
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Easier to do with under lever guns. The TX200 has a threaded cap on the compression chamber so it can be taken out and the TP can be threaded for sizing inserts by anyone adventurous and handy with a lathe.
-Marty
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This may help.
Pellet Rifle Swept Volume formula:
Rifle bore radius squared x Pi (3.14159) x piston stroke = cubed mm. Convert to cubed centimeter by moving
decimal point 3 positions left.
Example:
HW95L .22 caliber 26 mm Bore radius = 13 squared (1/2 diameter) = 169 mm x Pi (3.14159) = 530.929 x HW95L Stroke 85 = 45,128.9 mm cubed. Convert to CC (cubic centimeter) = 45.128 or 45.13 CC for Swept Volume.
Pellet Rifle Swept Volume formula:
Rifle bore radius squared x Pi (3.14159) x piston stroke = cubed mm. Convert to cubed centimeter by moving
decimal point 3 positions left.
Example:
HW95L .22 caliber 26 mm Bore radius = 13 squared (1/2 diameter) = 169 mm x Pi (3.14159) = 530.929 x HW95L Stroke 85 = 45,128.9 mm cubed. Convert to CC (cubic centimeter) = 45.128 or 45.13 CC for Swept Volume.
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I’ve decided I’m going to try the HO kit at full power before I do any spring trimming. The wife had shoulder surgery so I’m doing a lot more around the house but hopefully I can make time this weekend.
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Use the rifle a while before trimming the spring. Chances are you'll have a little bit of dieseling, the seal has to break in and the springs settle down after a couple, three tins.
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