N/A Do any PCP rifles have a bleed valve on the plenum to relieve excess pressure?

[stovepipe]

Are there any PCP rifles that come with a plenum bleed valve (knob or whatever) that would allow the shooter to bleed off excess plenum pressure for those times when the plenum pressure is above the reg setting?

You guys know how the plenum pressure goes up when the ambient temperature goes up -- like you take a shot when it's 60 degrees F and a few hours later you want to take a shot, but the plenum pressure is above your set regulator pressure because the outside temp is now 75 degrees F and the sun came out. You know your shot is going to be low FPS because of the high plenum pressure. So what do you do? If there was a bleed valve on the plenum, you could let a small amount of air out of the plenum and let the regulator bring the plenum pressure back up to normal and then take the shot.

So back to the main question -- are there any PCP rifles that come with a plenum bleed valve?

stovepipe

 

[PumaCarl]

I would think that most pcp with a dedicated bleed screw would do this, because I know that on some of my guns that have the dedicated screw it is releasing air between the plenum and the valve. That being said, it is way easier to just shoot that first shot off. Dry firing won't hurt your pcp, people do it all the time on an empty chamber, and it takes a second.

 

[stovepipe]

I would think that most pcp with a dedicated bleed screw would do this, because I know that on some of my guns that have the dedicated screw it is releasing air between the plenum and the valve. That being said, it is way easier to just shoot that first shot off. Dry firing won't hurt your pcp, people do it all the time on an empty chamber, and it takes a second.

The only rifle I have is an fx maverick 30 cal sniper which doesn't have a bleed valve for the plenum. I don't have any choice but to do what you said -- fire a mulligan -- or as the squirrels would say -- a warning shot. I didn't know if there were any rifles that had a plenum bleed valve, but thanks to your answer I now know that there are some. Thanks.

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[Peashooter]

On the AGT vulcan 3 and my new Epic Two there is a bleed valve, and it drain everything.

On my FX Maverick unscrewing the bottle take care of the fill pressure, but you have to do a few air shots to finally bleed thru the valve CUZ it do not have a bleed screw.

IMHO a bleed screw should be standard on all rifles. even if the Maverick setup are not terrible complicated.

Actually just running into a memory cookie, the Epic Two also have a #2 bleed screw in the front, so it could be it do not completely bleed the high pressure side if you just use the rear one,
But just doing the rear one it is safe to take the pipe off the Two, i have done that a few times now, but maybe if you want to take off the regulator it would be a idea to also use the front bleed screw.

And i will have to CUZ i got a regulator to rebuild rather untimely,,,,, and in a few days a new regulator to install.

 

[Peashooter]

The hissing of the bleed valve, would probably also scare off prey.

 

[PumaCarl]

Take a nice soft little pillow with a very breathable fabric covering on it and shoot into that with your supressor right on it and you'll only hear a click. Easy peasy.

 

[stovepipe]

On the AGT vulcan 3 and my new Epic Two there is a bleed valve, and it drain everything.

On my FX Maverick unscrewing the bottle take care of the fill pressure, but you have to do a few air shots to finally bleed thru the valve CUZ it do not have a bleed screw.

IMHO a bleed screw should be standard on all rifles. even if the Maverick setup are not terrible complicated.

Actually just running into a memory cookie, the Epic Two also have a #2 bleed screw in the front, so it could be it do not completely bleed the high pressure side if you just use the rear one,
But just doing the rear one it is safe to take the pipe off the Two, i have done that a few times now, but maybe if you want to take off the regulator it would be a idea to also use the front bleed screw.

And i will have to CUZ i got a regulator to rebuild rather untimely,,,,, and in a few days a new regulator to install.

Thanks Peashooter. My want for a plenum bleed valve is not for degassing the gun, but rather just to release a SMALL amount of plenum air to bring it below the reg pressure and let the reg bring it back to normal before taking a shot. This would only be used when ambient temperatures have risen enough since my previous shot that the reg pressure is too high for my tune.

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[caliusoptimus]

I've wondered this as well. Not just for getting the plenum back to set pressure, but also for degassing the gun. Would be nice if manufacturers would include a simple thumb screw to cover both purposes.

 

[stovepipe]

The hissing of the bleed valve, would probably also scare off prey.

Yeah, I thought about that. A bleed valve is probably never going to be available for my maverick, but I'm glad to know that at least some manufacturers have put them on their guns. It would be nice if they were controllable enough to let air out real slow so as to not make a loud hiss. Maybe some of them are -- I don't know.

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[Peashooter]

My Two regulated pressure just climbed to the fill pressure ( 200 BAR ), so regulator not working too well over time at least, but i shot it for 2 days and saw nice strings and wholesome fun.
and the rifle lying still for 12 hours or so in between my Thurs and Fri sessions was no problem, but a week or two seem to be.

Bleeding off a little pressure before lowering REG settings might be needed in the future, well at least on my brand new Two, CUZ i have been extremely gentle with going down in pressure, only going b 20 or so bar in each adjustment step and blank shots in between.

Mind you the Two do seem to have a " hot " first shot, but thankfully i am not in need of precise first shots, so in the worst case i would just send that into the ground.
Unsure if it is a regulator problem or a side effect of the balanced valve in the two.

 

[stovepipe]

Take a nice soft little pillow with a very breathable fabric covering on it and shoot into that with your supressor right on it and you'll only hear a click. Easy peasy.

I only hear hammer ping as it is, so it's not too bad if it's only a dry fire.

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[stovepipe]

I've wondered this as well. Not just for getting the plenum back to set pressure, but also for degassing the gun. Would be nice if manufacturers would include a simple thumb screw to cover both purposes.

Yeah, something like a thumb screw was what I had pictured in my head.

stovepipe

 

[jarmstrong]

how much is the plenum pressure climbing? and does it affect a fifty yard shot point of impact?
this is my way of asking is it a real problem or just my OCD when I look at a gauge?

for hunting tunes, I like to have just a little more hammer spring power than needed for the plateau/knee, to over come those first shot, low velocity due to reg creep or in your case , thermal induced pressure creep

 

[coastal drifter]

Leshiy2 bleeds everything with a screw. no need to dry fire or open a gauge.

 

[stovepipe]

how much is the plenum pressure climbing? and does it affect a fifty yard shot point of impact?
this is my way of asking is it a real problem or just my OCD when I look at a gauge?

for hunting tunes, I like to have just a little more hammer spring power than needed for the plateau/knee, to over come those first shot, low velocity due to reg creep or in your case , thermal induced pressure creep

Excellent questions! I'm still working on a new tune for my maverick that will take these questions into consideration. My buddy is the one who does the real-world shooting (hunting mostly) out of town and I'm the "mechanic" that tries to set things up (tune the rifle) based on his feedback. I can't keep up with him hiking or even walking on level ground, so I stay home mostly. So, logistics really slows down the progress of my/our setup (tuning). I'll ask him to keep an eye on the "over pressured" shots to see how much the reg pressure actually climbs and how far off his 55 yard zero shots are off relative to the reg pressure. If we are really lucky, I may have it tuned pretty well already. Again, really good questions. Thanks.

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[Peashooter]

can't keep up

I know the feeling, my default walking pace are now way too fast for me, so walking i constantly have to think about that, or in a mile or so get a severe urge to grab my inhaler, and sit down for a while.

From 45 to 55 things went down hill really fast for me, knocking on 60

 

[stovepipe]

how much is the plenum pressure climbing? and does it affect a fifty yard shot point of impact?
this is my way of asking is it a real problem or just my OCD when I look at a gauge?

for hunting tunes, I like to have just a little more hammer spring power than needed for the plateau/knee, to over come those first shot, low velocity due to reg creep or in your case , thermal induced pressure creep

Excellent questions (continued)! I just now talked to my buddy. He got the new maverick tune (tune is new, not the maverick) sighted in at 55 yards. Temps were probably in 80's and 90's, clear and sunny, no wind. He said that ambient temperature changes didn't have much effect on shot placement at 55 yards. BUT, going from shade to direct sunlight was driving the plenum pressure up from 161.5 to over 170 bar in fairly short periods of time and that was totally messing up his shot placement (first shots after moving into sun). Black anodized aluminum loves to soak up direct sunlight and get hot as hell. His solution so that he could take advantage of the no-wind conditions (rare) was to go get a white towel and drape it over the scope -- so the towel was also hanging down below the plenum and shading most of it. That solved the shade to sun problem. I guess we'll have to make a camo dress for the mav. I don't think there is any way I can come up with a tune that will work well at 161.5 and over 170 bar.

My mav has the 1:18 twist superior heavy liner. We're shooting nsa 54.5 gr slugs at about 935 to 955 fps (can't be sure because I don't trust my chronographs and we haven't validated yet via empiracle data on targets at different ranges). I was quite happy to hear that he shot 10 3-shot groups at different aim points on the paper and all groups were 0.5 inch or less center to center. That's way better than I expected.

stovepipe