Chinese air rifles and Gas spring conversions



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Offline Scotchmo

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Re: Chinese air rifles and Gas spring conversions
« Reply #20 on: November 01, 2011, 12:27:43 AM »
All this is great informtion and I do respect your research but, I would have to say that messing with using these rams or springs you mention in a QB-57 -58 is treading dangerous ground. As it is now, the trigger system is almost to weak for the stock spring they use now. I would recommend staying away from any power mods on the QB's. One could lose a finger very easily on these models.
True. Be careful. Messing with any stored energy device of this level can be dangerous. Gas spring or wire spring. That is why I suggested the Blue and Red label gas springs. They are the closest to the stock spring as far as stored energy. A small increase (10-20%) beyond stock is about as much as I would feel comfortable attempting. I felt a little uneasy testing the Yellow spring. And I never let go of the cocking lever when it is retracted. The Yellow spring was removed right after an hour of testing as I did not want it used anymore.

Total spring energy when cocked:
N-Forcer 19x080 BL - 27 ft-lb
Stock TF58 spring - 36 ft-lb
N-Forcer 19x080 RD - 40 ft-lb
N-Forcer 19x080 YW - 54 ft-lb - not recommended

Maximum return force:
N-Forcer 19x080 BL - 130 lbf.
N-Forcer 19x080 RD - 195 lbf.
Stock TF58 spring - 212 lbf.
N-Forcer 19x080 YW - 260 lbf. - not recommended

The gas spring produces a more constant force throughout its stroke. That is why it can deliver more total ft-lbs of energy with a lower peak spring force. The TF58 trigger system is a copy of the Gamo trigger system. I have a GRT trigger installed. The trigger system is adequate for springs that are close to stock as far as force. The Blue and even the Red label gas springs have less trigger load than the stock spring. I am not doing, and I don't advocate doing this as a way to increase the power a large amount. A small increase would be nice but my main goal is to have an improved shot cycle. The gas spring produces no torque when extending. That increases accuracy and can decrease hold sensitivity. I know that careful lubing and tuning using a wire spring can minimize the torque, but the gas spring eliminates it.
« Last Edit: November 01, 2011, 01:00:46 AM by Scotchmo »
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Offline gene_sc

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Re: Chinese air rifles and Gas spring conversions
« Reply #21 on: November 01, 2011, 01:07:51 AM »
You data and what you have posted is very intriguing to say the least. With my R&D using the Crosman NPSS, NP and XL gas rams has been quite an exciting exercises in performance. Although I do not know what these gas rams are rated at I have found they work consistently well with the conversions I have done. Especially on the Stoeger, and older Daisy's. One issue is room for the rams in certain instances. I have had to re design a couple springers in the trigger and spring block section on a couple when using the XL rams due to length.

I would love to be able to converse with these people and find out if the pressures can vary with the different length strokes of the piston. For example can these rams be ordered with different pressures of nitrogen in different overall lengths. There is a world of things a tuner can do with many of the non piston seer style springers.
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Offline Scotchmo

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Re: Chinese air rifles and Gas spring conversions
« Reply #22 on: November 01, 2011, 01:52:21 AM »
I don't know about custom lengths, but you can order custom pressure within the allowable range. The 19mm diameter springs go up to about 260lbs. Does the NPSS and XL use a larger diameter piston? The next size up in gas springs is 25mm and they are available in longer strokes. Maybe these larger gas springs would work in the rifles with larger pistons.

There is a limited selection of standard strokes so I pick the one with a stroke that is just a little longer than the stroke in the particular rifle. I'm lucky in that the rifles that I have been working on match up fairly closely with the standard gas piston stroke lengths. I leave a little room for preload so that the spring does not experience damaging "top out" during firing or "bottom out" during cocking. The spring usually has to be spaced up to fit. If a particular spring does not quite have enough travel, and the next size up won't fit, I think I could add a spacer under the piston seal in order to shorten the stroke of the rifle slightly. Like you said, the spring block might need to be drilled or cut back to add a little space if the gas spring is a little too long. I have not had to do this yet, though I will have to cut down the spring guide in my TF99.

I suspect that the Crosman springs may be based on dies springs. Maybe they use custom lengths. I'm curios if they are the same dimensions as stock die springs. Compare them to those in the die spring catalogs that I linked to. You can check the force with a bathroom scale and a press. Dies springs are high friction devices. The compression force is significantly higher than the extending force. So you have to release the press slightly to get an accurate measurement of extension force.

What do you mean by "non piston seer style springers"?

I too have been learning a lot and having fun experimenting with these combinations of low priced rifles and high quality gas springs.
« Last Edit: November 01, 2011, 01:57:10 AM by Scotchmo »
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Offline Scotchmo

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Re: Chinese air rifles and Gas spring conversions
« Reply #23 on: November 08, 2011, 03:49:26 PM »
Here is some interesting test data:

Rifle: TF58

Pellet: AA 7.33g

Blue label 19x080 ASRaymond gas spring, strut forward, heavy tophat - 670fps average
Red label 19x080 N-Forcer gas spring, strut forward, heavy tophat - 730fps average
Red label 19x080 N-Forcer gas spring, strut forward, light tophat - 710fps average
Red label 19x080 N-Forcer gas spring, strut backward, maximum spacer weight - 770fps average

Putting the strut in backwards is actually easier and in this case, the added piston weight improves performance. Adding weight to the piston assembly does not always increase performance and sometimes makes the shot cycle harsher. I still need to do a good accuracy comparison, but the shot cycle still seems OK. So for now my preferred way to mount the gas springs is with the spring body inside the piston.
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Offline z28rod

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Re: Chinese air rifles and Gas spring conversions
« Reply #24 on: November 10, 2011, 10:32:16 AM »
Scotchmo can you post some pics of the process it would help to see what your doing alot thanks.
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0351_Vet

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Re: Chinese air rifles and Gas spring conversions
« Reply #25 on: November 10, 2011, 11:03:09 AM »
Great Post.....Lots of info.

Question: What is the advantage of a Gas Spring over a Conventional Spring?

Offline rsterne

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Re: Chinese air rifles and Gas spring conversions
« Reply #26 on: November 10, 2011, 01:58:15 PM »
The two obvious advantages to a gas spring:

It can be left cocked indefinitely without harm....
It has no "torque" (twisting) reaction when firing....

One disadvantage:

It will change in power in relationship to the absolute temperature because the internal pressure changes....

I'm sure there are other effects that can be argued, but those are the obvious ones from a quick look....

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0351_Vet

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Re: Chinese air rifles and Gas spring conversions
« Reply #27 on: November 10, 2011, 02:08:22 PM »
So....Do you like Gas Springs over Springers Bob?

Offline rsterne

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Re: Chinese air rifles and Gas spring conversions
« Reply #28 on: November 10, 2011, 02:25:35 PM »
Never had one....

Bob
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Offline Scotchmo

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Re: Chinese air rifles and Gas spring conversions
« Reply #29 on: November 10, 2011, 07:47:56 PM »
Scotchmo can you post some pics of the process it would help to see what your doing alot thanks.
The pictures are of a QB57. I picked it to show since it is easier to disassemble than the TF58 (no scope to deal with). The two actions are almost the same. The only difference in the parts is that the spacer for the end of the gas spring needs to be a little longer than the one for the QB57. The action of the QB57 is about 3/8" shorter than the QB58. The stroke is about the same. The spacer for the QB57 is .28" long. It is 3/4" diameter with a .81 diameter lip at the start that keeps it centered in the piston. The spacer has a countersunk recess for the screw that holds the spacer onto the gas spring. That is how I did it. I have a lathe to make the parts but if you don't, there are many other ways to center the gas spring and space it to the correct length.

The first picture shows the ASRaymond/McMaster blue label 19x080 gas spring, the top hat/spacer and the spacer screw. These are the only parts that were added. You can discard the original wire spring, top hat and spring guide.

The second picture shows the gas spring assembly.

The third picture shows how the gas spring rod nests into the spring cap. The QB/TF/5758/67 need no other modifications. On other models, you may have to cut off the plastic spring guide and make a metal spacer to center the rod.

The forth picture shows the gas spring being inserted into the action.

The last picture shows the cap in place before compressing. There should be at least a small amount (maybe 1/8") of preload in the gas spring to prevent it from topping out when the rifle is fired.
« Last Edit: November 10, 2011, 08:08:52 PM by Scotchmo »
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Offline z28rod

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Re: Chinese air rifles and Gas spring conversions
« Reply #30 on: November 10, 2011, 09:05:47 PM »
Thank you Scotchmo , this is very cool. So what kind of fps does that give you on the qb57 ? is it 177 or 22 cal. That would be a cool rifle at 700 + fps in .22 cal.
« Last Edit: November 10, 2011, 09:08:06 PM by z28rod »
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Offline Scotchmo

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Re: Chinese air rifles and Gas spring conversions
« Reply #31 on: November 10, 2011, 09:21:25 PM »
Thank you Scotchmo , this is very cool. So what kind of fps does that give you on the qb57 ? is it 177 or 22 cal. That would be a cool rifle at 700 + fps in .22 cal.

The .177 QB57 that currently has the "Blue" ASRaymond spring is shooting 7.33 grain AA Falcons at 720fps average. It is lighter than the stock spring so very easy to cock.

The .177 TF58 that currently has the "red" N-forcer spring is shooting the same pellet at 776fps average.

These rifles have fairly small chamber volumes. So they are well suited to .177 caliber. A .22 QB57 would probably max out around 600fps with 14-15g pellets.

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bang45

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Re: Chinese air rifles and Gas spring conversions
« Reply #32 on: November 15, 2011, 09:32:10 AM »
The best info for airgun enthusiast!

Offline z28rod

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Re: Chinese air rifles and Gas spring conversions
« Reply #33 on: November 15, 2011, 05:01:10 PM »
That is still a decent velocity 600 fps .22 cal. qb-57.
« Last Edit: November 15, 2011, 05:03:33 PM by z28rod »
  • Hopewell Junction, NY
- Crosman Titan .22 Cal. W/3x9 Weaver and Leaper one piece mount and rings, tuna gold trigger. Under dime 25yrds. Cphp's.
- RWS 320m .177 4x RWS scope in mint condition.Getting tuned by dad the pro.
- B-28 .22 Cal. Fully Tuned by my dad the pro tuner. RWS 3x9 AO scope. BKL mount with magnum rings.
- Winchester 1000x .177 made by Hatsan, Turkish walnut stock.
- Beeman G1000 .177 mint.
- Hatsan 85 camo .22 Cal. w/4x Leapers scope.
- Crosman 760 in mint condition. Wood stocks. Oldie but goody.

Offline pappa

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Re: Chinese air rifles and Gas spring conversions
« Reply #34 on: November 16, 2011, 01:43:30 PM »
Does anyone know if it is possible to convert a B25 or B28 to gas piston?
Thanks for any helpful contribution.
Crosman 2100 .177
Crosman 2200 .22
Benjamin Regal w/Nitro Venom .22 barrel
Ruger Air Hawk Elite .177 - Self tuned
Ruger Air Hawk .177 & .22 - Self Tuned
Ruger Blackhawk .177 & .22 - Self tuned
Xisico B25 .177 - MM tuned
Remington Summit .177 & .22 - Self tuned
Crosman Nitro Venom .177 & .22 - Self tuned
RWS34 T06 Classic .177 & .22 - Self tuned
Ruger Air Magnum .177 - Self tuned
RWS350 T06 Magnum .22 - Self tuned
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Offline Scotchmo

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Re: Chinese air rifles and Gas spring conversions
« Reply #35 on: November 16, 2011, 02:04:47 PM »
Does anyone know if it is possible to convert a B25 or B28 to gas piston?
Thanks for any helpful contribution.
Short answer - No

Although anything is possible with enough work. A standard gas spring will not just drop in. The B25 and B28 have a latching rod down the center of the piston. They would require a redesign of the piston and trigger assembly.
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Offline pappa

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Re: Chinese air rifles and Gas spring conversions
« Reply #36 on: November 17, 2011, 05:18:08 PM »
Scotchmo,
Thanks! Now I can stop dreaming about it.
Crosman 2100 .177
Crosman 2200 .22
Benjamin Regal w/Nitro Venom .22 barrel
Ruger Air Hawk Elite .177 - Self tuned
Ruger Air Hawk .177 & .22 - Self Tuned
Ruger Blackhawk .177 & .22 - Self tuned
Xisico B25 .177 - MM tuned
Remington Summit .177 & .22 - Self tuned
Crosman Nitro Venom .177 & .22 - Self tuned
RWS34 T06 Classic .177 & .22 - Self tuned
Ruger Air Magnum .177 - Self tuned
RWS350 T06 Magnum .22 - Self tuned
RWS460 T06 Magnum .22 - Self tuned
Mendoza RM577 .177 - Retired

Skjold

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Re: Chinese air rifles and Gas spring conversions
« Reply #37 on: November 18, 2011, 07:37:32 AM »
What about a Beeman RS2?  I would love one of these in a gas piston.

Offline Scotchmo

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Re: Chinese air rifles and Gas spring conversions
« Reply #38 on: November 18, 2011, 03:34:03 PM »
What about a Beeman RS2?  I would love one of these in a gas piston.

Yes, the RS2 should be a fairly simple conversion. The trigger looks very similar to the higher end Tech Force rifles. The trigger latches on the piston skirt so there should be room for a gas spring. No promises - just my observations.
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Skjold

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Re: Chinese air rifles and Gas spring conversions
« Reply #39 on: November 19, 2011, 02:33:59 AM »
I am getting a Beeman RS2 when I return from Afghanistan.  I will be in Maine where is gets pretty cold but would still like to be able to shoot.  I hear the Gas Springs do not suffer from the effects of the cold like wire springs do.  I like the duel caliber option of the RS2 which is why I am getting it. A gas spring would make this a good multipurpose all weather rifle.  Would the "Red" spring give it the same or perhaps a slight bump in power as well?  I know you do not recommend the "yellow" but I would also like to get a slight to moderate increase in power if possible. ;)

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