GOOD AND BAD BOUT NITROGEN PISTONS???

[greyskullnz]

No we are on the same page when we are discussing "gas ram" technology.

The Theoben world wide patent protection has expired.

The Theoben agent in NZ has been manufacturing these and installing them for a fair while now. I have two that have been converted so far and another planned.

Sort of speaking from a position of experience. ........

Interesting comment earlier on the use of various pellet weights with gas rams. Yes I agree, as I have used the heavy Eun Jin's 28.5 gr, and also the Piledriver 30gr pellets. They really do pack a punch at range with no possible adverse effects on the power plant. The rifle still shoots sweet when launching a 30grainer!

Cheers
GS

[gldprsp]

I have a Gamo Whisper VH with a Air Venturi Gas Ram install by PA. I have had it for about 3 months I guess and it has been nothing but trouble. First it trashed the Gamo scope that came with it. No big loss there I figger. Next it trashed a Leapers 3-9X40AO, knocked a bunch of duff loose inside. Don't know what that stuff was, it was stuck to the inside of the back lens. Leapers was good about replacing the scope, except they sent me a scope mount for a M-16 instead of my scope. They got it right the second time though. Any way back to the whisper. My scope stop setscrew egged out the hole a little. I ended up taking that setscrew out, its a 10-32 thread and retapped it to a 1/4 - 20. You can get any size setscrew at about any good hardware store. That stopped the scope base from moving. I have a Leapers Accutrac one piece scope mount on it now. Now I find out my scope is moving inside the rings and they have the tape inside to prevent that sort of thing from happening. I just sent the whisper to Gene, he is going to take the gas ram out and put a new spring back in. My whisper has a synthetic stock and I think the recoil is just too much for it. Maybe if you have a wood stock it could handle the recoil a little better. I was always getting 2 or 3 flyers after putting 2 pellets in the same hole. The flyers were off 2 to 3" scattered all over. Some say even the power varys from ram to ram. What good is it if it isn't consistant?

Chas

Springers I currently own: RWS Diana 34, .177, Gamo Whisper Deluxe, .177, G RT- III trigger, Turbo Tuned by Gene and arriving soon on a slow,slow boat from Germany a Beeman R-9, .20 cal

Your not lost if you don't care where you are.

[greyskullnz]

Agree with you, a bad install can cause problems. I tested three different power rams before settling on a 650N ram. 600 N was oh so sweet and gentle +accurate. 650N was perfect for power/accuracy compromise, and a 700N was shaking the whole rifle to bits.....screws coming undone, scope shift etc etc. Although I have never lost a scope yet to damage.

It is part of an intelligent install to sort this out before on selling to the final owner. That is where problems can occur. A smart installer knows the model being converted, and can advise on the correct power ram to install. Just something to consider if people are investigating getting one installed. There is not a "one size fits all" gas ram, and it is a technological principle, not just one product.

I also agree with the wooden stock being a calming influence on the recoil/jerk of the abrupt ram stroke. Mine are all walnut stock'd air rifles.

cheers
GS

[gldprsp]

PA didn't give me that option, that there were different power levels of the gas rams. Maybe the Air Venturi only comes in one power. I am thinkin that the gas rams are a point in the right direction in the development of a different power supply. The only thing is there is just one power level that I am aware of. Now if I could adjust the power level and match it to the air rifle its to be installed in, that could be a good thing.  Better yet lets have a power adjustment screw on the action we can fine tune it with.

Chas

Springers I currently own: RWS Diana 34, .177, Gamo Whisper Deluxe, .177, GRT- III trigger, Turbo Tuned by Gene and arriving soon on a slow,slow boat from Germany a Beeman R-9, .20 cal

Your not lost if you don't care where you are.

[airiscool]

I put an Air venturi in my Whisper .22

The Gamo scope quit long before I did the swap, so I can't blame that on the air venturi. So did a couple of other "non-springer rated' scopes I tried.  The Leapers Mini Swat I have on it now has held up fine.

The 30 mm Leapers one-piece mount I put on egged the stop pin hole and cracked the end of the 10-32  pin that came  in the mount. I drilled out, re-threaded, and installed a 1/4-20 bolt in the scope mount with the bolt shoulder, not threaded part, into the 1/4 inch hole in the reciver. Now, the pin fits the hole nice and snug and  it's fine.

Acuracy was still variable, but that was traced to a blown seal which had started long before I installed the air venturi. The increased power of the air venturi only degraded the bad seal faster. I put in a new seal and acuracy is back.

Does it have more power now? A big YES ! But since I plan on using it for critters not paper that's a plus for me. And, I don't have to worry about leaving a spring cocked while hunting.

Does it kick more? Yes! But it's a nice, sold 'thunk' and the gun is steadier to shoot than it was with the original spring. The increased kick hasn't affected acuracy.

Is it any louder? After some break-in shooting, not that I can tell from the muzzle noise, and there certainly is less noise from the power plant.

Would I install a gas ram in any other springers I plan to hunt with .... in a heart beat !!!!!!!

Would I do it to a target gun ? No, the gas ram didn't increase acuracy so I see no advantage with a target gun !

And now,  Crosman also seems to think sinking alot of money into gas rams is worth doing.

Paul.

[AKJC1977]

I am very grateful for all the input you guys have gave me on this post, However I still have a feeling it is one of those things where it is your own personal preference. Myself the big thing for me was: Can I shoot whatever weights I want? and Does it last longer or at least as long as a well cared for springer? I think that this technology could be developed to be a lot better than a spring,in the future. But as for now I think it is too close to what its replacing to justify the cost. Just my opinion of course. I would definately try one if I had more springers. But I have only two good springers and one is my sons,So I guess I will just have mine tuned. I plan on buying more guns in the future, as finances allow.AKJC1977

[oldpink]

Good news!
I was having some severe scope skid after I had the Air Venturi gas ram installed in my .22 caliber Gamo CFX, so I finally went with the option that looked the most promising.
I used that tape you see tennis players use to wrap their racquet handles to make them easier to grip.
I have now fired well over 100 pellets of varying weights, from the lightweight H&N Field & Targets through the super-heavyweight Eun Jins.
I see no evidence of skid at all now.
I was able to get it pretty well sighted in through the course of all that shooting, and I will get it dialed in the rest of the way, probably sometime Wednesday.
Should the scope hold still, and the accuracy be as good as I expect it to stay, I will let you folks on here know that this is the way to go with a hard recoiling gas ram conversion rifle.
btw...the tape I used is the "Tourna Grip" brand, available in the sporting goods section of any Wal-Mart, and probably any sporting goods outfit out there.
I'll let you know how it goes.
 

[AKJC1977]

Good deal now ya can focus on your groups. Hope it holds up good. AKJC1977

[greyskullnz]

There are two other solutions to the sharp recoil problem.

Use heavier pellets to provide more of a cushion of air in front of the ram/piston. I found that going from 16 grain pellets up to 18 grain helps, but 30 grain Piledrivers are the best. While the pellet speed is reduced, the action is sweeter so accuracy is enhanced. Getting the cushion of air before the piston head just right is the key......

Shorten the stroke of the ram by spacing in front of it, and shortening the rod accordingly. The speed and momentum that the piston achieves at the end of its stroke is the problem, so shortening the stroke length means it reaches the end of the stroke earlier, is a slower action  and is not as violent. Similar if not identical energy is maintained.

GS

[oldpink]

greyskullnz - 8/17/2009  7:37 PM

There are two other solutions to the sharp recoil problem.

Use heavier pellets to provide more of a cushion of air in front of the ram/piston. I found that going from 16 grain pellets up to 18 grain helps, but 30 grain Piledrivers are the best. While the pellet speed is reduced, the action is sweeter so accuracy is enhanced. Getting the cushion of air before the piston head just right is the key......

Shorten the stroke of the ram by spacing in front of it, and shortening the rod accordingly. The speed and momentum that the piston achieves at the end of its stroke is the problem, so shortening the stroke length means it reaches the end of the stroke earlier, is a slower action  and is not as violent. Similar if not identical energy is maintained.

GS

I had noticed that some time ago, even before I had the stock spring replaced with the gas ram.
I was surprised when I found that by far, the smoothest shooting pellets were the super-heavyweight Eun Jins.
However, those are probably a bit rough on a spring, but I can shoot those whenever I feel like it with the gas ram.
The only problem is that they drop significantly more than any other pellet, about 2 mils more at 25 yards!
I could foresee using them to dispatch raccoon sized mammals within 15 yards, though, as they really pack a wallop.

[kidscollegefund]

gldprsp - 8/14/2009 2:24 PM

I have a Gamo Whisper VH with a Air Venturi Gas Ram install by PA. I have had it for about 3 months I guess and it has been nothing but trouble. First it trashed the Gamo scope that came with it. No big loss there I figger. Next it trashed a Leapers 3-9X40AO, knocked a bunch of duff loose inside. Don't know what that stuff was, it was stuck to the inside of the back lens. Leapers was good about replacing the scope, except they sent me a scope mount for a M-16 instead of my scope. They got it right the second time though. Any way back to the whisper. My scope stop setscrew egged out the hole a little. I ended up taking that setscrew out, its a 10-32 thread and retapped it to a 1/4 - 20. You can get any size setscrew at about any good hardware store. That stopped the scope base from moving. I have a Leapers Accutrac one piece scope mount on it now. Now I find out my scope is moving inside the rings and they have the tape inside to prevent that sort of thing from happening. I just sent the whisper to Gene, he is going to take the gas ram out and put a new spring back in. My whisper has a synthetic stock and I think the recoil is just too much for it. Maybe if you have a wood stock it could handle the recoil a little better. I was always getting 2 or 3 flyers after putting 2 pellets in the same hole. The flyers were off 2 to 3" scattered all over. Some say even the power varys from ram to ram. What good is it if it isn't consistant?

Chas

I've had an identical experience with my .22 Whisper - after 1500 shots, 3-scopes busted, scopes sliding around, dieseling, 4" flyer shots - just sent it back to Pyramyd. I love the power but the other issues with it have left me with buyers remorse...just picked up a Crosman NPSS. The Crossman doesn't have as much power but a much more consistant and solid feeling.

[mze]

Hi Adam,

What ram has been the best in your Mod 55 so far?

600N, 650N or 700N?

Regards
Vincent

[greyskullnz]

Alex still has the 55 and is using it to test various power rams. Best ask him direct what the best set up is.

I am using the mod 60 currently, and the 650N ram is awesome. No scope problems, but have to use heavy pellets for best result.

cheers
Adam

[greyskullnz]

The Eun Jin heavies are an acceptable option, as are the Piledrivers. I would think a 21 Grain Barracuda (.22 cal Kodiak) would work very well too.

It basically is still spring piston theory.....just replace the metal spring with a ram. The learned tuning experiences of the past are still valid and can be applied, with a more consistent and less fragile component in place of the spring.

Crosman are on to a winner, and yes power is not everything. The saying that "ya can't kill what ya can't hit" applies to gas rams too. Tuning for the optimum performance is more important than sheer brute force, as always.

cheers
GS

[AKJC1977]

With all this said, I have heard some really logical opinion's. And it makes me wonder if the nitro series crosman rifle's come from factory with a gas piston? Are they designed around the nitrogen power plant? If so they by all account's should be the best of the gas driven piston gun's.That is just the only one I know of that comes straight from the actual maker with that design. All the Gamo's and others are just modified by a distributor to use gas piston.Those Nitro Crosman's ain't cheap,but I would love to hear opinion from someone who has used one hard for couple year's. Maybe we can expect a gas piston powered gun in the near future with a adjustable valve on it to adjust velocities and accuracy or something really interactive?AKJC1977