Is there a low operating pressure PCP out there?

[Back_Roads]

 I have a Benjamin Wildfire,  , If anyone knows of a 850 psi regulator that would fit the air tube, It would make a great low fill pcp, fill to 2000 may shoot down to 850, I have run it tethered that way and was impressed. 
https://www.walmart.com/ip/Benjamin-WildFire-BPWF17-PCP-Air-Rifles-177-Cal-Multi-Shot/55465366

[Spacebus]

I have a Benjamin Wildfire,  , If anyone knows of a 850 psi regulator that would fit the air tube, It would make a great low fill pcp, fill to 2000 may shoot down to 850, I have run it tethered that way and was impressed. 
https://www.walmart.com/ip/Benjamin-WildFire-BPWF17-PCP-Air-Rifles-177-Cal-Multi-Shot/55465366

Doesn't that already have a 2k max fill?

[Back_Roads]

I have a Benjamin Wildfire,  , If anyone knows of a 850 psi regulator that would fit the air tube, It would make a great low fill pcp, fill to 2000 may shoot down to 850, I have run it tethered that way and was impressed. 
https://www.walmart.com/ip/Benjamin-WildFire-BPWF17-PCP-Air-Rifles-177-Cal-Multi-Shot/55465366

Doesn't that already have a 2k max fill?

Yes but they work like carp, if you fill them past 1000 psi

[splitbeing]

Chronied the 1357 with this thread in mind.

From 1400psi down to 1000 psi, got 40+ shots at 720 to 750 fps. Very quiet. 9gr apolo pellets. Usually shoot ftts a little faster but my reup hasn't arrived yet and I'm basically out.

[c_m_shooter]

My BSA Scorpion likes a 2400 psi fill after I cut a few coils off the hammer spring.  The "power wheel" on the Air Force guns mostly reduces the pressure where you will hit peak velocity.  My Condor SS liked wound way down with a small top hat for 20 ft lbs and a 2200 psi fill pressure. Mauraders are also simple to adjust to whatever fill pressure you want them to work at.

[Spacebus]

I tuned my Stormrider today to 14.5 FPE with a 100b reg and a Chaser hammer spring, it's very hand pump friendly. Wes can ship a 'Rider with a very similar tune. Still pretty loud without a moderator, so I feel like there may be some air waste. Perhaps even less hammer spring or a reg that can be set lower would be more efficient. Disco regs fit in a Stormrider, so I need to research that option

[splitbeing]

I tuned my Stormrider today to 14.5 FPE with a 100b reg and a Chaser hammer spring, it's very hand pump friendly. Wes can ship a 'Rider with a very similar tune. Still pretty loud without a moderator, so I feel like there may be some air waste. Perhaps even less hammer spring or a reg that can be set lower would be more efficient. Disco regs fit in a Stormrider, so I need to research that option

The buckrail suppressor and adapter i bought for the qb 78 i jammed onto the dragonfly (basically a multipump stormrider). It's not only super quiet at 8 pumps, it also tightened my groups up a bit. Might work on the stormrider to quiet it down.

[Spacebus]

I tuned my Stormrider today to 14.5 FPE with a 100b reg and a Chaser hammer spring, it's very hand pump friendly. Wes can ship a 'Rider with a very similar tune. Still pretty loud without a moderator, so I feel like there may be some air waste. Perhaps even less hammer spring or a reg that can be set lower would be more efficient. Disco regs fit in a Stormrider, so I need to research that option

The buckrail suppressor and adapter i bought for the qb 78 i jammed onto the dragonfly (basically a multipump stormrider). It's not only super quiet at 8 pumps, it also tightened my groups up a bit. Might work on the stormrider to quiet it down.

I have an OEM moderator that makes the muzzle report very quiet, I should have clarified that the report without the moderator sounded like it was wasting air.

[splitbeing]

I tuned my Stormrider today to 14.5 FPE with a 100b reg and a Chaser hammer spring, it's very hand pump friendly. Wes can ship a 'Rider with a very similar tune. Still pretty loud without a moderator, so I feel like there may be some air waste. Perhaps even less hammer spring or a reg that can be set lower would be more efficient. Disco regs fit in a Stormrider, so I need to research that option

The buckrail suppressor and adapter i bought for the qb 78 i jammed onto the dragonfly (basically a multipump stormrider). It's not only super quiet at 8 pumps, it also tightened my groups up a bit. Might work on the stormrider to quiet it down.

I have an OEM moderator that makes the muzzle report very quiet, I should have clarified that the report without the moderator sounded like it was wasting air.

[thumbs up]

[Relentless Holiday]

I find it curious after reading all of this discussion that installing a Canadian-spec transfer port in the PR900 did not make more of a difference than it did. It dropped the muzzle energy down to ~7.5 fpe, which is about a 65% decrease from the original TP, but the shot count only went up from 20 to 40. Shouldn't it have gone up to 60 since I was getting only one-third as much muzzle energy per shot?

Yeah that's a no. The relationship between increased shot count to FPE/shot change is not linear or lateral math wise.   

[AlanMcD]

I find it curious after reading all of this discussion that installing a Canadian-spec transfer port in the PR900 did not make more of a difference than it did. It dropped the muzzle energy down to ~7.5 fpe, which is about a 65% decrease from the original TP, but the shot count only went up from 20 to 40. Shouldn't it have gone up to 60 since I was getting only one-third as much muzzle energy per shot?

Yeah that's a no. The relationship between increased shot count to FPE/shot change is not linear or lateral math wise.

Not only that, but reducing air usage by just restricting the transfer port is not the most efficient way to reduce energy (as it leads to a strong pressure differential across the port, thus reducing flow efficiency).  You would gain a few more shots at the same energy if you retuned the valve output, but it's probably not worth the effort if you like how it is shooting now.

[HOSPassassin]

I originally started this thread because I was dissatisfied with about 20 shots at 21-ish ft lbs in .22 with a PR900 (regulated Diana Stormrider). Putting in a Canadian-spec transfer port that cut the muzzle energy by 65% did not give nearly as many shots as I was hoping for. I really liked the gun except for the fact that it seemed to have a really poor pumping-to-shooting ratio.

So, if I were to get one in
.177 caliber,
unregulated,
possibly tuning it for lower power, in the 12-15 ft lb range,

would it get a better shot count after I figure out the optimum fill pressure and shot curve? I have learned over the course of this thread and a few others that 1. Regs take up space that could otherwise  be occupied by air, 2. .177 requires less air in general, and 3. Unregulated guns can be very consistent if you put in the time to adjust them to exactly what you want.

The Stormrider/PR900 is not a low-pressure gun. It does go all the way up to 200 BAR. But, I have learned that it doesn't need to be filled to that level necessarily. It also seems to be the best I can do for a value proposition for a variety of reasons. All of the other inexpensive, low-pressure PCPs mentioned above have different things about them that make them less appealing than a Stormrider.

[Spacebus]

I originally started this thread because I was dissatisfied with about 20 shots at 21-ish ft lbs in .22 with a PR900 (regulated Diana Stormrider). Putting in a Canadian-spec transfer port that cut the muzzle energy by 65% did not give nearly as many shots as I was hoping for. I really liked the gun except for the fact that it seemed to have a really poor pumping-to-shooting ratio.

So, if I were to get one in
.177 caliber,
unregulated,
possibly tuning it for lower power, in the 12-15 ft lb range,

would it get a better shot count after I figure out the optimum fill pressure and shot curve? I have learned over the course of this thread and a few others that 1. Regs take up space that could otherwise  be occupied by air, 2. .177 requires less air in general, and 3. Unregulated guns can be very consistent if you put in the time to adjust them to exactly what you want.

The Stormrider/PR900 is not a low-pressure gun. It does go all the way up to 200 BAR. But, I have learned that it doesn't need to be filled to that level necessarily. It also seems to be the best I can do for a value proposition for a variety of reasons. All of the other inexpensive, low-pressure PCPs mentioned above have different things about them that make them less appealing than a Stormrider.

The Stormrider in 177 is crazy inefficient. Peak efficiency comes in 25 cal. I was using an Altaros reg (100b) in a 50cc Bandit tube, 9" 25 cal barrel, and 220b fill for 18 shots at 12 FPE. I'm getting right around 40 shots per fill on my 22 cal 'Rider with a 100b reg and Chaser hammer spring at 14.5-ish fpe. Mind you all 40 shots are almost the same velocity. I could probably get close to 50 shots since it's only just starting to fall off the reg at shot 40+.

I'm getting about the same number of shots at 19 FPE with my bottle Bandito in 177 cal with a Stormrider barrel, but it has about twice the HPA volume as the Stormrider. This means the efficiency is abysmal, but I wanted to make tiny holes at the highest velocity possible. (10.03 JSB at 925 FPS)

[Baco]

if that's a 9ci bottle (~220cc) and your storm tube sans reg has 75-80cc you have nearly 3x the volume

have you tested shot count with the 2 regs to check how plenum volume impacts efficiency?

[Spacebus]

if that's a 9ci bottle (~220cc) and your storm tube sans reg has 75-80cc you have nearly 3x the volume

have you tested shot count with the 2 regs to check how plenum volume impacts efficiency?

It's a 9 ci bottle, about 147cc I mean to say 50% more volume in the earlier post. I didn't think to check the efficiency with the dual regs, but I suspect it would actually be a bit lower. Very little of the massive 50cc  plenum is being emptied for each shot. When the plenum pressure crept from heat it took two shots to go from about 2,100 to 1950 PSI on the plenum. I think it only takes one shot if dry firing since that uses way more air. I may still go with dual regs in the future with the 9 ci bottle, but only when I get the plenum volume right for max power. I suspect a modified valve with a space age material (PEEK, PEI, etc.) poppet could really make some more power. I'm also curious if more hammer strike could help with making power, but I'm going to wait until my upgraded cocking handles get here. The Stormrider spring is already pretty heavy.

[Baco]

if that's a 9ci bottle (~220cc) and your storm tube sans reg has 75-80cc you have nearly 3x the volume

have you tested shot count with the 2 regs to check how plenum volume impacts efficiency?

It's a 9 ci bottle, about 147cc I mean to say 50% more volume in the earlier post. I didn't think to check the efficiency with the dual regs, but I suspect it would actually be a bit lower. Very little of the massive 50cc  plenum is being emptied for each shot. When the plenum pressure crept from heat it took two shots to go from about 2,100 to 1950 PSI on the plenum. I think it only takes one shot if dry firing since that uses way more air. I may still go with dual regs in the future with the 9 ci bottle, but only when I get the plenum volume right for max power. I suspect a modified valve with a space age material (PEEK, PEI, etc.) poppet could really make some more power. I'm also curious if more hammer strike could help with making power, but I'm going to wait until my upgraded cocking handles get here. The Stormrider spring is already pretty heavy.

holy confusing units, you were right that would be 2x discounting the space occupied by the reg(~80cc my estimate)


do tell more about the upgraded bolt handles

[Spacebus]

if that's a 9ci bottle (~220cc) and your storm tube sans reg has 75-80cc you have nearly 3x the volume

have you tested shot count with the 2 regs to check how plenum volume impacts efficiency?

It's a 9 ci bottle, about 147cc I mean to say 50% more volume in the earlier post. I didn't think to check the efficiency with the dual regs, but I suspect it would actually be a bit lower. Very little of the massive 50cc  plenum is being emptied for each shot. When the plenum pressure crept from heat it took two shots to go from about 2,100 to 1950 PSI on the plenum. I think it only takes one shot if dry firing since that uses way more air. I may still go with dual regs in the future with the 9 ci bottle, but only when I get the plenum volume right for max power. I suspect a modified valve with a space age material (PEEK, PEI, etc.) poppet could really make some more power. I'm also curious if more hammer strike could help with making power, but I'm going to wait until my upgraded cocking handles get here. The Stormrider spring is already pretty heavy.

holy confusing units, you were right that would be 2x discounting the space occupied by the reg(~80cc my estimate)


do tell more about the upgraded bolt handles

You're right, It is twice the volume when including the bandit tube, but the tube/plenum is only 2k PSI compared to 150cc of 3k air in the bottle. The Stormrider also has the Altaros reg, which is pretty huge. I posted some photos comparing all the stuff on my other thread. The Altaros reg will tolerate 220b fills on the Bandit tube, which I have done regularly. With a 220b fill I'm betting the shot count would be closer to 50+, but that's the antithesis of the thread. However, I always fill to 220b when I'm using the hand pump, for more efficiency of shots per pump strokes. A microbore hose would help.

Upgraded bolt: https://www.ebay.com/itm/294824411242?var=593178413047

[splitbeing]

Went back to adjusting the hammer on the 1357 with this thread in mind.

From 1800 to 1200 psi, getting 45 shots with a high of 787 a low of 741 an ES of 46 and avg fpe at 11.

Narrow that string to 40 consecutive shots from shot 2 to shot 42 and its getting
40 shots with a high of 787 a low of 760 an ES of 27 and avg fpe at 11.5.

Not bad for a $250 wood underlever bullpup running on a low pressure fill. Easily 3 mags of good enough power and ES for inside 50 yds.

The pellets used were ftt 4.50.