Canadian Airgun Forum

I looked around for answers to this, so I'm hoping it's not a repeat of a repeat....
I'm in the process of getting my PAL, I'm in Atlantic Canada. I'm 53yrs old, so I'm ancient! I grew up around guns, used to own a few when I was 14 (12 gauge & a .22 semi-auto rifle) but things have changed obviously. I still like to shoot targets. I've got no interest in hunting anything not rats, not Elk, and nothing in between.

I bought the Crosman F11 with the Nitro piston. After seeing how easy it was to increase FPS, I became curious since I'm a tinkerer. Looks like I got the wimpy model with the pretty pathetic BT5M22-00-1A piston. I read about the BT7M22, as well as the BT9M22, so you can imagine my next questions:

• Am I stuck at 495 FPS with the current piston? Can anything be done to it or the rifle to, hypothetically, improve the FPS without completely replacing the piston?
  
• Is there a way I can source one of the older pistons from within Canada, or legally into Canada from elsewhere? I'm in Atlantic Canada & while I see these pistons available on Ebay, I don't want to break any laws trying to import something, especially while I go through my PAL process.

Thanks, gang. Not sure what the legalese is for people looking to mod FPS, but I'll be clear so no one's worried about their advice being risky - any options to increase the current ~495fps of my Crosman F11 are in the context of "when I get my PAL", not before. I'm also looking for the pistons that CAN be modded, but are not currently modded. I'm looking for stock parts with the pressure relief holes intact, that are designed for previous-gen, Canadian-market, Crosman nitro pistons.

Appreciate any help.
- James

Once the is PAL in hand it is very easy to fill the hole in the piston by threading the hole from the front with a bottoming tap and make a plug out a 3/8 bolt. When installing the plug it is best to use permanent Loctite (red). I have purchased the 60KG gas ram from Ebay from Australia, it took about 2 weeks to deliver. There is a chance the full power ram may be in stock from Crosman Canada, it just is not when ever I need one.

Robert

Thanks, Robert! You wouldn't happen to have any site or YT channel that shows how to do that, do you? I'd order the part from Australia but I reckon it would be denied @ customs without my PAL. I've reached out to Crosman for one of the full power pistons (495 fps before mod), so I just want to get a piston that's customizable when the time comes. Since it used to be sold in Canada with the older pistons, I'm hopeful there's someone who's willing to part with a used one or Crosman can dig one up for me. I'm wondering if the old ones are 'verboten' due to their ease of mod.

Appreciate the advice, so feel free to drop any links you might have. Happy New Year!

- James

I have uptuned an F11 for a friend. Yes, he has a pal.
The rifle had a 190mm piston (and the holes). I have seen a few 170mm pistons, but that was the first 190mm I have seen. You can buy a 150mm piston from Crosman Canada. They may still have free shipping over $50. You can also buy a full power nitro strut. Both are a drop in fit. If out of stock, order and they will ship when new stock arrives. In my experience, it's usually within a month or so. I installed the sub-500 strut from the F11 in a sub-500 Crosman Fire with a 170mm piston (with holes). I filled the holes, left it 170mm long, and dropped in the (more powerful) strut from the sub-500 F11. The longer piston gives a short, snappy shot cycle. It shoots 8.4gr pellets at 625, 7.2gr at 700. Member Tcooper cut 5" off the ridiculously long barrel including a well done crown. I shoot it a lot. The reason I mention all this, is keep the weak strut! With a 150mm full power piston and the weak strut, you will probably see over 550 fps. It would make a nice quiet mid-velocity gun for winter basement plinking.

_________________
Theory is when you know how something works, but it doesn't.
Practice is when something works, but you don't know why.
In my shop, Theory and Practice are combined!
Nothing works and I don't know why.

Two lathes and too many projects

Thanks, I think I'm a bit green to do much of this so I don't want you guys to go to trouble helping me figure it out. I'm a total beginner, I bought everything at Canadian Tire, including the pellets. I have the rifle apart & I'm putting it back together tomorrow.
I don't know for sure what the strut even is, though I'm assuming it's the thing the piston drops into. The piston is 260mm long, the strut is 190mm long (plus the plastic-looking 'stopper' at the end). If that IS the strut, then there's an indent near the middle of the end of the strut, something intentional - looks like someone scored it with a drill bit. From what I understand, that's supposed to be flat - so I wonder if that's another "FPS reduction step". I can't measure FPS, but I'll know if the power improves once I fill that in. Right now I've poured krazy glue into that drill bit score (it's no deeper than a penny, half the diameter of a dime) but I'll see if I can find some JB Weld for that instead.
Since it's the .22 calibre, the standard pellets I've bought are 14.3gr & 17gr (5.5mm) - so obviously I didn't get light pellets - assuming that's not because they're not .177 but because they're domesticated male products, lol. If there is a slight improvement in fps from filling in that drill score on the flat end of what I think is the piston, with the calibre & pellets, I'm pretty sure I'm not at risk of exceeding 495fps.

And 'winter basement plinking' is kind of the whole purpose of this thing - I like it because it's quiet. I'd like something at least twice as powerful but not too noisy. In 1983 (I was 13), I made a makeshift silencer for my 22 rifle (slide-bolt, mag-fed, 8 shot clip). It worked too well! It only lasted 3 shots before being torn off by the muzzle flash or something. It's illegal to silence a firearm in Canada, so a pellet rifle that'll get ~1k FPS & not wake up the next door neighbors would be ideal once my PAL is complete.

Thanks again!

Yes sir, there is a way, being that you don't have a pal it would be difficult to ĺexplain here. You would have check some other forms. It so simple, read up air flow,and porting that should get you started. You only to get $550 without changing the piston.

Thanks, Kevlin, I'm not sure what the rules are, but I'd appreciate any advice on how to go about this, PAL or not. I'm just being careful since I'm too lazy to read the forum rules, but when it comes to a generic Canadian Tire air rifle, I'm more than happy to gather all the knowledge I need while I wait for my PAL to be processed. It ffeels ridiculous to have to waltz around such a benign topic at this point out of some murky sense of "intent to alter" something any slob off the street can buy.

I can do searches of course, so I'm just looking for hypotheticals & generalities now, whatever you're comfortable with. What might be simple to someone who's done it, might be a bit difficult for someone trying it for the first time. I barely know the difference between the piston & the strut...I think lol.

The piston, on the thick end of it, there's a small indent. I'm trying to attach that image to this post. It looks like someone used a drill press, made an indent, then painted over it. Would there be any potential FPS improvement by adding JB Weld to fill in that indent?



I didn't notice any holes in the strut or piston that would affect the piston pressure. TBH, I'm a bit jealous that others were given nitro pistons that are so easily augmented, effectively doubling the FPS, while I, a man in my 50's, have to look around for ways to improve it so it's at least minimally effective. I knew I was getting a 495 fps (at best) air rifle, which I'd bet is closer to 400fps. I have a Crosman Glock style CO2 powered .177 pistol that gets about the same FPS & it's like 425fps tops. I was under the impression a few easy mods would potentially improve that performance. Now I find out Crosman went way above & beyond in an effort to effectively neuter this product. Their due diligence has evolved into condescending.
Once I get my PAL (I'm booked for the PAL course next month), I intend to come back to this forum & get some advice on a proper air rifle. The F11 Nitro rifle is, let's face it, not a quality product. The piston is good tech, but the rifle itself is what one might expect to find at a Canadian Tire store. So, I'm looking to mod this thing in any way reasonable so I can get some stank on these FPS numbers.

Thanks for your help, and any links you can advise, be they in this comment or via DM (if they even exist here), I'd appreciate it. In case this helps: my intent is NOT to exceed the Canadian limit of 495 fps, but to improve the FPS so it's closer to 495 than it is currently.

Disregard the previous post, please. I've learned a bit since I posted it & can't find the delete option. I'll put a better post together asap.

Everybody, thanks for being patient & helpful with me. I will relent & let this thread die, I just have questions that only experience can answer. Questions are to help me understand how to increase the FPS in my air rifle & any mods that put my rifle over the Canadian limit will not be attempted before I have my PAL in hand. I'd like to benefit from the experiences of other tinkerers like myself, so I don't either ruin the rifle or head down a pointless path & do something stupid like JB Weld my barrel shut.

My situation:

I have a Canadian version of the Crosman Nitro Piston ("F11"), 22 cal. It comes with a weaker Crosman Nitro Piston (compressed nitrogen) designed for 495fps therefore weaker than PAL-required gas rams. Older versions of this rifle in Canada came with the full-power gas rams, but to decrease the FPS, there would be a bleed-hole in the head of the piston. That particular method of sealing the bleed-hole shut proved too easy, & has been circumvented by a wimpy gas piston, putting me, a man in his 50s, in the same category as a teenager. My sulking aside, I do not intend to break any Canadian guns laws, I'm in the process of getting my PAL, these mods are for then. I'll then likely just get a 'real' air rifle, we'll have to see. Since I'm a beginner with modding thise kind of tech, I'm hoping some of you can advise if I'm on the right track.

What I understand (please correct me?):

The gas ram sits inside the piston, which surrounds the gas ram like a metal sheath. Cocking the barrel compresses the gas ram & when the trigger's pressed, the piston is released, the gas ram decompresses, forcing the piston toward the end of the compression mechanism, where the Transfer Port sits. Air is sent through the Transfer Port, which then regulates the air pressure toward the pellet & down the barrel. The shooter hits a bullseye, women start noticing him more & he's basically a god. Just checking if you're still with me.

The piston's front end is tipped with a white, slightly opaque, hard plastic 'cap', which seems to allow the piston to travel repeatedly down the firing breech without scraping the walls along its path.

The air pressure that's generated through this flat-tipped piston propelling forward through the mechanism is then sent through the transfer port, which is a hole slightly thinner than the barrel opening where the pellet sits. Since the gas ram always releases the same amount of force (compressed nitrogen) & assuming the piston doesn't have any bleed holes:

The most common method in improving FPS is increasing pressure in the chamber by decreasing the amount of space. Adding a 'shim', often a washer or even a coin, can significantly increase FPS. The gas ram's power & the piston's velocity are unchanged, but the pressure they generate in the chamber is increased. Decreasing the amount of space to contain this pressure too much can prevent the rifle from properly cocking & the rifle might be inaccurate. Adding shims in increments is recommended.

The second most common method is by slightly enlarging the size of the Transfer Port hole so more initial pressure is created simply by allowing more air to get through to the pellet. This method can decrease FPS if not done correctly, since it is effectively increasing the amount of space in the pressure chamber - 'more air at once', but 'less air in total'.

Of course, my questions:

* Where does a shim go? Is a washer placed over the Transfer Port? Some say coins can be used - are they meant to be JBWelded to the front of the piston to simply increase the piston's length? To be clear, the intent is not to shorten the length of the piston's travel, but rather to decrease the total volume of the space through which it travels, correct? What items can be used, where are they best placed, how are they affixed? What's a good way to start?

* How close does the piston get to the Transfer Port when the rifle's fired?

* If increasing FPS beyond, say, 750 causes inaccuracy, then why are the PAL-required air rifles firing at 1200-1500 fps without issue? Are they not using the same configuration but with stronger gas rams? Some suggest a 550fps is healthiest, but is the weaker gas ram simply already maxing out the pressure it can potentially build?

* Can more powerful gas rams be purchased otherwise, or perhaps be built to specs, by companies specializing in such things?

* What kind of lubricant should the piston be treated with? The same oil that Crosman sells for the barrel?


Another big thank you to you all, and hopefully the answers will provide other newbies with the info they need.

1: The piston bottoms out on the end of the tube when fired

2: Because springers are so hold sensitive as the velocity increase so does both recoils. This alone will decrease accuracy for someone that is has not yet developed the hold

3: When you buy gas rams from a secondary manufacture you by size and weight that it takes to compress 50,60, and 70 kg are some that I have seen. When filling the hole in the piston of one of my Crosman it went from 450 to 600 fps with the same gas ram and was close to 900 fps with full power ram.

Robert

Yep, if only my Crosman piston had holes to fill I could put that on my list - but the cause here is just a wimpy gas piston. If there's extra recoil, it'd be an honor to feel it, tbh. The barrel is so long on this rifle, I'm not sure how it could ever be inaccurate, but if I could get another 100 FPS, it could be as indescriminate as a grenade & I'd be happy.

I'm stuck with a Nitro Piston system whose only hope for better FPS is apparently a shim, which so is, so far, a theory involving coins, bolts or washers. A higher power Nitro Piston is something everyone's had their hands or eyes on, but is also impossible to get unless I have the honor of being an American or being lucky enough to buy a Crosman nitro piston 5yrs ago instead of 2 months ago.

Re: when you said the piston bottoms out at the end of the tube, then the shim theory as I understand it, doesn't exist. Where else would a shim be added? Between the gas ram & the inside front of the piston?

Thanks for the reply, though - I appreciate any & all advice - this is just getting frustrating. I'm trying a couple more posts to
get to a specific step to follow & if not by then, I'll give up.
When my PAL is finalized, maybe I'll just admit that this rifle is a toy & recycle it.

The Crosman Canada site is insanely slow & whoever manages their Canadian site should be in court answering for it. Their data layer is the slowest I've used in over 25yrs in I.T. - Every selection results in a backend query (15+seconds!) that must get the entire database each time. Their parts search indicates that they have about 200 obscure parts available, with about 3 million other parts on back order or obsolete. They don't seem to be serious about selling aftermarket parts - not to Canadians at least. $10 to ship a tube of chamber oil the size of a AA battery, etc. The American Crosman site, however, is lightning fast & helpful.

No problem , No problem, your reply with the answer is correct. I use penny for the shims when they just started. You can find some formal washer is enough that the gasram won't compress it. And like you said , make sure you get the proper drillbit size for that port , and because if you screwed it up , that's it, and in gas piston they are three different power types, the are all 1/3 of each other . Make sure you put the shims from the butt side, because the top will decrease your volume. BT5M22-00-1A is ok to use its a physical manufacturer restriction, and the stronger BT9M22-03-00 is too strong and will cause massive recoil for the power output. So, it's not necessary to put a stronger ram. Good luck tinkering. When you do get your PAL, a recommended break barrel is the benjamin NP trail I'm my opinion. It's a good value for your money and power.

Kevlin, thanks so much for your advice. I don't think I'll mess with the transfer port 'til I know exactly what I'm doing there, but for certain, when I get my PAL (ugh it takes forever), I want to get a Benjamin airgun. Well, actually I'm leaning toward the Trail XL Magnum. The 'Vaporizer' (lol, really?) looks really good, but I assume it's a bit cheaper for a reason. Maybe I'll go back to .177, but I like the .22 cal 'effect'. I'll post questions in other parts of this forum about that, but if I get my PAL even this year, I'd be surprised (bureaucracy). I'm fine following the rules of course, but some of the guys I know with their restricted license, yikes. Paranoid.

I just want to plink Monster Energy cans in the basement without the neighbors calling in SWAT. I intend to get a real hunting rifle when I get my PAL, but I don't want to hunt. I buy meat at the grocery store & outsmarting an elk while soaked in estrus isn't on my bucket list. I can delete rats with an airgun if I need to 'hunt', but I don't feel good shooting benign animals, especially for no reason. I just find stuff like this cool, would be a great project to buy a hunting rifle & save up for a great scope. I'd like to see how good I can get with targets at great distances. Odd hobbies, electric scooters, electric guitars & guns. That's me.

Thanks kindly!

James - you are 20 years my junior and I'm not the oldest here, I am sure.
Welcome, btw.

_________________
Best Wishes
Daryl

Good to know the curiosity doesn't fade! Thanks, hope we see more "wise old men" round here!