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RoccoJohnson · New Member

Hi, I'm new to the forum, so I apologize if this has been asked before.

Does anyone have any info on converting a pump action pellet rifle to a CO2-powered unit? I have a Benjamin Sheridan C9, 20 cal. rifle that I'd really like to be able to convert to run off of CO2, via a 9 oz. paintball tank.

A couple of my lovely neighbors like to feed raccoons, (aaargh,) which, of course, brings them, as well as their buddies, from miles around for the free meals. There's 1 or 2 every year that appear diseased, and, because none of the other neighbors will do anything, I end up having to dispatch them.

I use my Benji C9 for this "thinning of the herd," which is generally very effective, but, unfortunately, it's not always possible to kill the raccoon on the first shot, which then requires I set off on foot in hot pursuit to finish the job. Problem is, it's very difficult to reload the Benji, then pump it up 8 times for maximum power- all while on the chase.

I can not use my semi-auto .22 to take care of the problem, both, because of the potential for a stray bullet, and, the loud report of of this gun when fired. The power of the Benji is quite suitable for the task, and I use it every year for this purpose, but it would sure be nice to be able eliminate the need to pump it up eight times. Because I have no where near the budget to afford a repeater right now, I'd love to know if it's possible to convert the gun to CO2 power.

Anyone ever hear of this, or know how to do it?

AirGunEric · Site Admin

As the noise level is one of your issues- we need to know how much pressure builds up in the Benjamin valve at 8 pumps. Anyone have any ideas?

Once we have this, we can then compare this to the pressure of Co2 at a specific temperature (i.e. 68*F) to determine if they are in the same basic ballpark. If so, not a problem. If, however, the Benjamin is at 600psi and the Co2 is at 850psi- you will then be getting more noise out of the Co2-converted rifle.

That being said, and I'm not too familiar with the specific configuration of the C9, as long as Co2 can be fed to the valve, and the valve can handle the Co2 pressure (likely) to be able to fill and then empty when the hammer strikes- it can be done. However, depending on the volume of the Benji valve- you could end up wasting alot of Co2- which might get expensive after awhile, or cause you to empty your Co2 reservoir rapidly.

Anyone an expert on the C9 setup?

RoccoJohnson · New Member

Fortunately, I own a 55lb. CO2 tank for refilling my paintball cylinders, so wasting a bit of gas isn't a big problem.

As for the noise, I have some leeway in the range of the volume I can get away with. The cluster of 6 houses where my house is located is ringed by woods on two and a half sides, and no other neighbors nearby in those directions.

Using subsonic rounds I can get away with shooting my .22 revolver in the backyard on occasion, but I never shoot it more than a couple of times in a row, because its definitely loud. Unless during the day, when some of my neighbors are away, I doubt if I could get away with shooting it from the front yard. Shooting the .22 rifle, obviously, is out of the question.

I can, however, shoot the Shermy from pretty much anywhere in my yard without attracting much, if any, attention. It's pretty commonplace for me to do this, and I even target shoot off the back deck sometimes, with no one raising an eyebrow. My Sherman "E" series pistol is CO2 powered as I mentioned, and because of the shorter barrel its not all that quiet with CO2 blasting through it, but, as with the C9 no one ever even bats an eye.

Thanks for the response.

jlwilliams · Veteran Member

Considering the amount of work you would have to do for the conversion (which translates to time with the gun apart and not functioning), would it be worth your while to get another air rifle?

RoccoJohnson · New Member

My first preference, and the best solution, would be to buy a new gun, but with this economy, it'll be a long time before that could happen, which is why I'm hoping to cook something up with the one I have.

That said, I don't want to destroy the Benji, so I wouldn't attempt a conversion unless someone out there has done it before and can tell me it works. Although I have the technical skills to do, I don't want to end up screwing up the gun.

jlwilliams · Veteran Member

I know what you mean. Some projects have a way of getting started and never put back together. Maybe 'just waiting' for a part or some other stumbling block that keeps it from being done. End result being that the donor item is non functional and the new-improved version isn't in hand either. I have more unfinished projects than I care to admit. Don't get me wrong, I finish enough of them and I have the tools and experience to finish many of the unfinished ones too. It's just that there is always something that demands time now, and the side project ('side' meaning no cash at the end) gets back burnered in favor of payed work or home repair or what not.

If a few bucks come your way, Sheradin has a wickedly powerful .22 springer. Super Streak, I think it's called. Not cheap, but it's a lot of power for the money even if it's a bit heavy to carry around. The Crosman Quest is also a good gun for the money (around $100 with a scope) and I like how light weight it is. Crossman makes a CO2 powered 22 bolt action for really reasonable money (a little less than the Sheradin CO2 rifle) and Compasseco sells Chinese knock offs of everything. The Chinese guns are a bit crude, but for the price you can kill vermin with them. Years ago I got a Chinese 22 underlever that was the most powerful air gun I had personally handled at that time. It lasted a few years before some of the plastic bits started cracking. Still worked, just started deteriorating. By that time, I was sold on the idea that high powered air guns were for me and I was able to justify going for a better replacement for it. Don't rule out a low dollar 'interum' air gun. May be just what you need. If you haven't yet, you may want to search Compasseco's sight and see what you find.

My current air guns for vermining are a Marauder (so glad I bit the bullet and bought that) and a Crosman Quest 22. I don't use the Quest much now that I have the Marauder, but it's still my knock around. I'm willing to use it in places and weather where I won't take the more expensive Marauder.

Back to your original plan. I think it's a neat idea and I'd also like to see if it's been done and/or like to see it when you do it. Good luck whatever you decide to do.

jlwilliams · Veteran Member

As soon as I was done typing the last one, I though of something else.

A project I've been meaning to try but never have is building a pellet gun out of canibalised paintball parts. They are pretty modular. You could put a piece of airgun barrel into a paintball barrel easily enough. (crooked barn sells crosman barrels cheap) Just sleeve it to fit the paintball pipe. Feed pellets singly through an enlarged port into the barrel. It wouldn't really be a repeater, but the open bolt design of most paintball actions would make loading the singles pretty quick.

If you are into paintball and have a lower end starter gun you don't use much, maybe you could try it wothout spending much money at all to start. Remember, 22 airgun barrels are a different bore that 22lr barrels, so a 22lr won't give you the best accuracy or speed with 5.5mm skirted pellets. I don't remember how much I paid for a full length (about 24") barrel from Jim at crookedbarn, but it was cheap. You could put one together and try it for function and power for less money than you may spend on re-plumbing a pumper for the tank. If it doesn't work, you haven't really done any un-doable mods to anything.

Food for thought.

RoccoJohnson · New Member

Hi JL, thanks for the tips.

I didn't think about the possibility of converting a paintball gun, but that could be a really good solution. I have a Tippman 98, and being its already a semi-auto it would allow me to escape having to pump 8 times before a second shot. I have big fingers, so loading small pellets will always be a problem for me, unless I can devise some sort of auto-feeder. There would be a LOT of things, like valving, among others, that I'd have to experiment with and learn, in order to turn the single-shot Benji into anything close to equalling what the Tippman is right out of the box.

Secondly, I am going to check out the guns you suggested, as well as Compasseco. Something that's ready to go is the absolute best scenario for me, since I don't care to be a gun manufacturer, I just want to be able get powerful shots off quickly, as I try to hunt down this coyote.

Five of the pet cats in the neighborhood have now disappeared in the past month, and I'm pretty sure there's got to be a coyote to blame. But to be able to hunt him properly, (which won't easy,) I need every hand free that I can get.

jlwilliams · Veteran Member

Coyote

? I thought you were going after racoons with this.

Please keep us posted on the Tipman conversion. If you come up with a viable feed method to feed pellets into one, it would certainly be a big hit. I don't know who carries .22 round balls, but I know I've seen them for sale. They would be easier to feed out of a hopper.

I have a beater paintball gun in the garage. Maybe I'll mess with it a bit, but then again I have a number of open projects going now........

BSH9A · Member

i have converted my h9a its posted in picture gallery it normally hold 35 to 45 psi with valve mods up to 65 psi and me 800+psi out of stock valve

BSH9A · Member

ok here goes if you have a tippman should go easy remove pump arm assy remove valve assy should look like picture (1) unscrew in center will be loc-tited part 397-038 put in drillpress or drill smooth of edge facing spring for air flow i took mine down to dia. of rubber (2) from exsisting outlet hole to barrel drill 1/8 hole on 45 angle to just behind where rubber seats 30 degrees ok just need more direct route for air (3)on part 397-034 drill hole large enough to tap to 1/8 27 pipe thread dont drill all the way into chamber leave a lip for a washer to hold spring because you will remove part 1322-056 you will need to strech spring a little air pressure does the rest ( NOTE ) if you want to pump again someday leave 1322-0056 in place and just drill enough to get 1/8 pipe to mount mine was a half inch befor i got to the seat fir the inlet valve . get enough pipe to come out end and back other way mount tank adaptor under barrel and pressure up
i went permanent cut bottom of pump tube came straight down to gauge and hose back to tank mount