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CrowGunner · New Member

hey i picked up a beeman 1040, and i was wondering if i can make it shoot over 495 fps, im 19 and i have my pal, is there anywere i can mod it .. its my first project and i thought it would be cool !1 =) thanks for the replies

AirGunEric · Site Admin

That particular Canadian model Beeman is also known as the SH-650 minus the scope and muzzle brake, and detuned (the Canadian 1041 is actually a genuine -detuned- SH-650).

Amazing the absolute lack of info out there on modifying these guns, huh? Don't know what's up with that- other than perhaps it's just not a popular gun for modifying.

In any event- seeing as how you're in Canada, I would urge you to review Canadian airgun and gun laws before modifying anything related to power if it may bring it above 500fps. That being said- any "tuning" you do to bring it right up to 499fps would be completely legal and still not make it a "firearm" under Canadian law. And- virtually no "off the shelf" detuned Canadian model airguns I've ever heard of actually shoot at the "maximum 495fps" velocity listed to the box- you can tune/improve it to get it to 495fps, and the same modifications, carried a bit further would put it above that mark. To know what you have done at any given time during a tuning process- use a chronograph.

Anyways- what's to improve on a Beeman 1040/1041/SH650?

The "power" issues with this gun are common to all "spring" guns- spring pressure and piston air transfer (movement).

How are these things related to power output? The more air that can be loaded up behind a pellet and the faster it is released (volume and pressure) the faster/harder the pellet travels down and out the barrel. What this means is that to "de tune" a gun is that something has been done to change the volume and/or pressure pushing that air. How this is done is almost always through the same means, no matter what the manufacturer- reduce the amount of air that can be pushed behind the barrel by using a weaker and/or shorter piston spring or venting the transfer assembly or piston to let air escape out of the rifle before it reaches the barrel/pellet. There are all sorts of other possibilities of how they could do this, but everyone wants to do it the easiest and cheapest way possible without having to make an entirely new design just for special purposes or markets.

That being said:

From what I know of the GS650/1040-41 it has alot of stamped metal parts- i.e. the trigger and the seer. The seer is a weak link however- as being weak stamped steel it limits the amount of increased spring pressure that can be held by the trigger assembly. So what, you ask? The easiest way to get more power out of a spring gun is to put a longer/stronger spring in there so that when it is released it will pound air faster and harder through the piston. The other item is the transfer assembly at the top of the piston (or the top of the piston itself)- there may be a vent hole drilled into it to shunt some portion of the air (the amount would be dependant on the size of the hole) away from the barrel.

As you may have gathered- I don't own a GS650 or know anyone that does- so I'm speaking in general terms here (I can't even find a parts reference for this gun anywhere). When you fire the gun- can you hear pressurized air escaping from anywhere near the stock? If so- you have a vent hole either in the transfer assembly or in the piston itself- which needs to be plugged- with solder or by tapping a thread and inserting a plug- tapping and inserting a plug is the safest and most reliable method. If not- then likely the only "de-tune" method used was a weaker/shorter spring- in which case you need to either get another spring of the same outer diameter and either the same length but with a thicker coil wire (a stronger spring) or one that has the same outer diameter but is longer and has the same coil wire thickness (a "faster" spring)- or barring that- pull out the original spring and stretch it (which will take alot of effort and may be very unsafe) to make it 'faster'. To find new springs- you can check with anyone who offers new/replacement springs for a variety of airguns and see if they might recommend one for your application- or take your gun apart (be careful- I personally have no idea what might/might not fly out), get the spring out and measure it so you can compare with a vendor who can then suggest a good replacement unit. At least one spring vendor is listed in the "Want to Buy" area of the board if you check there.

There is a gentleman out there who was "prototyping" parts for the GS650/1040-series; I've emailed him and he's going to try and dig up some pictures of things and post them here- so maybe we'll get some more information soon.

Beyond that, hopefully more people come around here who have detailed knowledge of the Beeman SS (SuperSportster) line of rifles and can be more specific on this issue.

If you do decide to tune this gun- take pics and post them up so there's some reference out there for anyone else in your position in the future (if you have no way of hosting them- I will put them up on the site in permanent storage). Thank-You

Good luck, and I apologize for not having more specific information on this gun to offer you. Apology

Yietspingle · Member

I bought a Beeman 1040 awhile ago at Canadian Tire store. I lost the receipt, I had wanted to exchanged it. I didn't catch that these Beemans are made in China until I bought it and brought it home. Online some places stated "Made in Spain". I deciding to live with it, adding a spring from a 1952 machine gun that a friend had. I increased the power but didn't have a chrony at that time and need to check it sometime. I can shot through 3/8 ply wood from 15 feet which is barely penetrated before. The accuracy improved due to more velocity? I couldn't hit anything consistently before that. The sear & trigger were all manufactured from stamped steel. I doubt the sear is even hardened. With the increase in spring pressure I didn't trust the sear. As AirGunEric stated, the sears cannot handle increased spring tension.

Not completely finished the design, I am prototpying, trying not to modify the tube if I do not have to, I didnt' have to modify the tube. I added an adjustment screw to the trigger so I can determine when the sear releases the piston. Sear is A2 tool steel and trigger is 1045 steel. Have lots of off cuts so used the material out of convenience. Still some bugs to work out, fixed the sear releasing when gun was bumped. I improved the gun from the factory, even though it is a cheaper air rifle, $170 CDN. Might not be worth the effort in some people's opinion but it was good learning experience.

I will have to take a few more pictures of the parts. It will give you more ideas. Since this air rifle I moved on to build my first scratch built PCP.

Completed Trigger, polished assembled.
http://i25.photobucket.com/albums/c62/yietspingle/My%20Airguns/BeemanClose.jpg

Almost finished
http://i25.photobucket.com/albums/c62/yietspingle/My%20Airguns/DSC02860.jpg

Trigger semi finished
http://i25.photobucket.com/albums/c62/yietspingle/My%20Airguns/DSC02856.jpg

Original Trigger
http://i25.photobucket.com/albums/c62/yietspingle/My%20Airguns/DSC02827.jpg
http://i25.photobucket.com/albums/c62/yietspingle/My%20Airguns/DSC02842.jpg

Spring guide tube from steel not plastic, plastic tube all scrapped from dis-assembly.
http://i25.photobucket.com/albums/c62/yietspingle/My%20Airguns/DSC02837.jpg

Homemade tool to compress spring, take out trigger assembly. Used band saw vise to compress spring. Which the spring, if it slips you will loose some skin.
http://i25.photobucket.com/albums/c62/yietspingle/My%20Airguns/DSC02829.jpg

Any questions, information required you can reach me at airgun@mts.net

AirGunEric · Site Admin

You wouldn't happen to have any pictures of the spring/tube/piston assembly, would you?

Also- does the 1040 use a vented valve assembly (or any valve assembly?)- or is the gas path straight from piston-top through seal to barrel?

Yietspingle · Member

I will have to dissassemble the rifle and take some pictures. I have never seen a vent hole anywhere, not that it cannot exist.

Give me a few days and will try to get some pictures to show the rest of the gun inside parts.

Pedro

AirGunEric · Site Admin

If you can do that- that's even better than we could have expected. Definetly this topic will be a "keeper" for future reference. Thumb Up!

CrowGunner · New Member

i cant take the spring out, the trigger guard .. wont come out
can you help me please.. the spring put great tension so i cant move it. i moved the spring and the gurad was very loose but i still could not take it apart.. i think beeman airguns are purposly built bad so people cant mod them !

AirGunEric · Site Admin

I can't quite make it out on y-spingle's last picture- but it almost looks like he compressed the spring with that vise setup.

Can you remove the entire compression tube assembly, with the piston and spring (i.e. barrel off- and it pulls out the front end? Or how about a removeable rear cap to get the spring out the back? Of course- then you have to be able to compress the replacement to get it back in. Perhaps set-up a clamp system attached to a vise so you can loosen the rear cap without it moving, then release the clamp/vise slowly to extract the spring. This unfortunately, if you don't have the equipment already laying around, may get to be more hassle than it's worth. Of course, no one said modifying these things would be easy, right? Wink

Yietspingle · Member

Perhaps this might help. THe trigger assembly is tough to get out. You have to push it forward, knock out the pins and then release the pressure from the spring. Not an easy mod and will skinur knuckles if not careful.

I cut a piece of tubing to fit into the gun with a slot to clear the trigger. I cannot remember how I took out the pins with the tool in the gun. I will have to find it and take more pics.

Hopefully these help for now?

http://i25.photobucket.com/albums/c62/yietspingle/My%20Airguns/29.jpg

What you are trying to do is take the pressure off the trigger assembly. You have to push the spring guide tube forward and the trigger assembly comes out very easily.

http://i25.photobucket.com/albums/c62/yietspingle/My%20Airguns/27.jpg

Hope this helped? I won't have more pictures until late Saturday or Monday when I am back in the shop.

Yietspingle · Member

AirGunEric · Site Admin

Wow- that's quite the collection of pictures. This has to come in useful for alot of people!

Too bad the 1040 is not a great shooter for you. Did you check the barrel crown? Most mass-produced guns in the sub-$300 category seem to have very little quality-control- and the barrels/crowns are chocked out at the rate of hundreds (thousands?) per hour- so you may want to check that to improve on accuracy. My experience with Crosman products has been about 50/50- half come out of the box reasonably accurate, the other half shoot like cr@p and need a re-crown. I would've hoped that a more expensive Beeman would be different- but maybe not.

Yietspingle · Member

This is something I should look into.

I am sure this rifle could be more accurate as it shoots ~500 FPS consistently.

Accuracy tips? Anyone have some tips on this to try on a springer?

Yietspingle · Member

I have been doing some plinking with this rifle. Lots of blackbirds around lately. But never been able to hit any.

Setup a target tonight and tooks some shots. Horrible groups. Finally I realized that the barrel was never inthe same position as previously cocked. I took apart the rifle and tightened the hinge screw as tight as I could.

Then assembled and shot. WOW, that was it. I guess that screw has to be snug on a cheap springer like this. My groups went from almost 4" to under about 1" groups at ~30 feet.

However was cocking the rifle and the arm that pushes the piston back, something broke as it will not engage the piston. So another thing to fix.

All in all, I would not buy another Beeman that is made in china.

Petdro

AirGunEric · Site Admin

Sounds like a good tip Pedro. I have been unable to find any people who have successfully modded a Chinese-made Beeman with any sort of long-term success. Illness

I was hoping your project would prove that wrong. Shrug

I understand the Chinese-made Crosman's (i.e. the Quests) also suffer from barrel re-alignment after awhile- but there are brass barrel bushings available to correct and stop this (factory bushings are plastic).

Let us know what cracked- it's always interesting to find out what gets "blowed up" on things. Giant Grin

Yietspingle · Member

The cocking arm - push rod - has two prongs on it that push the piston back. When I got the stock off I saw that one of the prongs was broken off. So this cause the arm to unhook and could not push the piston back when cocking.

Now I have to make a solid cocking arm to replace the stamped steel. I will post some pictures when I get it fixed.

I checked out my old Vostok - has a really nice mechanism to push the piston back, might try to incorporate this into this gun.

Pedro