gas spring shot to $#@!

[infantry grunt]

Has anyone ever had a gas spring go bad on any rifle before.I have shot about 8 tins,and just did a tune on it.It was shooting great,I was soooo pleased with how the tune went,but in the past week I kept having to adjust the elevation up to keep it on the paper.I was suspicios of the gas spring,but the rifle being so new,I tried to rule it out.Then this morning when I took it apart I noticed the excess oil,and I could compress the gas spring with my hands.I was just curious if I did something or do they just go out.I did accidently dry fire the rifle once about 2 mos. ago,I was distracted during reloading and I thought I loaded it.Thats the only thing I can think of that I have done that could contribute to it blowing out,other than manufacturing defect.Any thoughts?

[ShakySarge]

Is this the Benji?

Never heard of it happening. Others may know more but I would be on the phone or email crosman and see what the deal is. Since you tuned it the warranty is void but they may send you a new piston. Not sure though cause they are pretty picky about selling just the piston.

Keep us updated and hopefully you can get her back in action soon!

Matt
(Another 11B Grunt)

[Nathan]

Sounds like a defective ram. I would definitely call Crosman and inquire about a replacement

Nathan

[MustangMike]

dry firing will only damage piston seals, the gas ram is defective and crosman will get you taken care of

[QVTom]

dry firing will only damage piston seals, the gas ram is defective and crosman will get you taken care of

I'm going to challenge your statement.  All manufacturers of gas springs, oem commercial (Crosman, Gamo, etc) or industrial (N-forcer, etc) warn about uncontrolled release in the their engineering notes.  They also have limits on the rate of extension. Exceeding these rates will decrease the useful life.  All gas ram guns exceed these design parameters in normal operation so the life of the ram is limited when compared to an application that stays within design parameters.  For us it is not a big deal because we don't shoot millions of cycles, many don't exceed thousands.  When it comes to uncontrolled release of a commercial ram it can easily become damaged and vent some or all of its gas.  Dry firing is an uncontrolled release.

Tom

Edit: You are correct about Crosman have great customer service and taking care of folks. 

[Scotchmo]

Tom,

You are right that an "uncontrolled release" is bad for a gas spring. But, a  properly installed gas spring will not experience an "uncontrolled release" from a dry fire. As long as there is some preload, the gas spring cannot top out, and that is what causes damage in an "uncontrolled release".

[infantry grunt]

Some very good points.Back when I dry fired it,I emailed crosman and asked for a couple of replacement piston seals and they sent them free of charge,Ive already emailed them bout the gas ram so Im hopin they will come through for me again,they even gave me a better scope a few weeks ago,not the best,but alot better.And no its not a benjamin,its a nitro venom dusk .22.I really like the venom,but after reading up more I wished I saved a little more and got a benjamin xl 1100,any ways thanks for the input,Ill just have to tell my wife to leave me alone when Im shootin so I dont dry fire again,lol.

[QVTom]

Scotchmo,

Yes and no, It depends on the definition of "uncontrolled release"  The worst kind is slamming into the end of the stroke but exceeding maximum rate is considered uncontrolled too.  A dry fire will definitely exceed the maximum rate of extension by a large factor and this is detrimental.  Especially to the lower quality and less robust commercial springs.

Dry firing will most likely destroy the piston seal (compression chamber) and cause other havoc before the ram is damaged but it is sill a consideration for the life of the
ram and not out of thee realm of possibility. IMO

Moller has a tome of information on extension rates in the technical section of their catalog.

Tom

Edit: After reviewing my previous post. I could have been much clearer about exceeding the rate of extension is uncontrolled as well.  At least the way I understand the term.

[ericclarkbandit]

I have had a ram go bad. It was about 2 years old and had about 500 pellets. I ended up just buying another off of the yellow forum.

[Scotchmo]

Tom,

I just did some reading of a DADCO installation guide. Here are some pertinent quotes from that guide:

"Pre-loading the pad will prevent
gas spring damage from sudden release."
"Overstroking the rod or impacting the top of the
cylinder will cause permanent damage."
"The maximum speed for gas spring operation prevents heat build-up
and prolongs gas spring life."

The Crosman gas springs may not be of the same quality but the information is probably applicable. The preload prevents the damage by what is described in the first and second quote. The maximum speed is another issue. No matter how we look at it - dry fire, heavy pellet, light pellet, we are greatly exceeding the maximum speed that the gas spring manufacturer recommends. Before I did my first conversion, I speculated on how they arrived at their maximum speed rating and if it might be a problem during airgun use. Progressive dies operate at a much higher cycle rate than an airgun. The manufacturer specifies a maximum speed that when used continuously, will not cause excessive heat buildup. We exceed that speed but we cycle our guns at such a slow rate that heat buildup is not an issue. Could the top speed and high acceleration/deceleration rates experienced in airguns cause problems? Maybe, but it would not be a heat buildup problem.

[QVTom]

When products are used outside their design intent it is always difficult to correlate the info given to to our nonstandard use. 

I don't think we disagree much.  I agree that high cycle rates will lead to heat build up that will cause problems but I've read literature that referred to both cycle and extension rate limitations.  I interpret extension rate limits to to be related to the amount of stress the seals and bushings can handle due to elevated friction which leads to wear at high speeds and cycle limits to progressive heat build up.

I'm not saying that a single dry firing will destroy a ram, just the fact that the extension rate during a dry fire is much higher than normal use and should be considered. Especially in a commercial unit that my not me made to the same tolerances, fit and finish as an industrial one.

Tom

[Nathan]

I don't think a replacement ram from Crosman will be too expensive. I asked about the price of a replacement ram (and other spare parts) for the Trail XL and IIRC it was $28 for the ram.

Nathan

[shadow]

I did lineup of tunes awhile back on the Trail NP's and the ram had failed on them. Several of the NP's were new with only a handfull of shot's through them. I heard rumers of some not up to spec rams being produced and failing early. As quickly as it happened it stopped and haven't had any problems with the rams on the shooters that I tune. Ed

[infantry grunt]

Price isnt too bad.I know Im still new in the game,but when the venom is dry fired and is fully extended I dont see how that being fully extended could harm it.Reason I feel this way is the gas ram is not fixed or bolted to the rear guide or at the front piston.Unless like said before it is the rate of the speed in which it is released,AND this totally slipped my mind,after I did my tune,I hold the trigger down and work the barrel several times just to make sure everything sounds OK inside.Now heres something else I did that could have caused this dilema,Ive read where people break there rifles in after a tune is 100 rds,200rds,500rds,and some say they group and shoot fine after just 10-20 rds.So guess what I did,I got me about 100 pellets out and just shot into the ground till they were gone,non stop.Scotchmo,could you explain to me about preloading the pad to prevent damage from sudden release.Im just trying to get educated as much as I can on everything,really,but this for now.Ha,my wife gives me a hard time ever since I bought this rifle,she wont let me have a firearm because of my ptsd,so I told her thats what she gets.These thing require more care than any firearm Ive ever used,you have to really take care of them.Sorry,just rantin'.

[infantry grunt]

I wonder if you can cross reference p/n's and buy a better quality gas ram from a company that specializes in these,rather than hittin up crosman for another?Maybe even an upgrade in power and durability,that would be nice,Im gonna see what google will pull up

[Scotchmo]

....Scotchmo,could you explain to me about preloading the pad to prevent damage from sudden release...

"Pad" is a term from the tool and die industry that was used in the gas spring installation manual. The thing that you need be concerned with is the "preload". I like to have at least 1/8" of preload. A little more might even be better. That just means that you have to compress the spring a little in order to get the trigger block installed.

If your rifle came with a gas spring, it should already have the correct amount of preload.

Gas springs of much higher quality are available. But you will pay more for them.

The Crosman gas spring made for your gun would be my first choice. They already determined a good compromise for cost, power, safety, and durability. But if you want to do the research and experiment...search for ASRaymond, Dadco, Design-tite, Kaller, Moeller, N-Forcer, etc.

[infantry grunt]

Trackin on the "pad".I did a google search and I dont know enough about gas rams to just go buy one cause it might be better quality,sooo,ya,I think I will let crosman handle this one.I plan on stocking up on some maintenance parts such as this.Thank you all for your input and patience with another one of "those guys"(you know,like me a newb)