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Air Gun Home Forum Index » Airgun Smithing » Browning Leverage tune (originally titled Nitro Piston conv)
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Browning Leverage tune (originally titled Nitro Piston conv) 
PostPosted: Sun Oct 13, 2013 7:45 am Reply with quote
Mentolio
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I've got my Browning Leverage .22 apart for a little tuning, and am looking for pointers on how to "size" a Nitro Piston for a spring gun. I'm not looking for more velocity (tho I'm also not looking to give any up!), I just want to smooth it out a bit, and get rid of the spring's really annoying "rattle-twang." Is it basically as simple as measuring the length of the spring you want to replace it with (both extended and compressed) and finding a nitro spring that is close? Will it even be worth it to change, or should I just stick with the stock coil spring and grease all heck out of it? And now for some pics...sorry about the image quality.







The spring guide/spring block made disassembly...interesting.




This is my improvised spring compressor. Worked fairly well, but I am considering modifying the spring block to allow the use of a proper spring compressor.



Here you can see a large rough spot on one side of the piston seal. This gun has just under 200 shots through it.


Here is the other side of the piston seal, where you can see a small defect or dimple in the sealing surface.





And the piston face: important? Probably not, but speaks to the low quality of the parts, I think. I have some new stuff on order for a QB that I'm told will work....EDIT: wrong piston seal, ended up going with a Gamo seal, and so far works very well. I have a Xisico seal coming in the mail. We'll see hoe that measures up. In the meantime, my Browning is up and running. Here's an example of a 5 shot group, fired at 20 yards, with a crappy scope, and using JSB Exact 14.35 domed pellets, which this gun seems to love.



Since the original post, I've given up on the whole "Nitro Piston " conversion. It just seemed like a lot of trouble to go thru on a gun that shoots so well, and feels so good. I've bagged a few squirrels with it, and really have no complaints. Is it as good as some high dollar European made underlever? Probably not...but this gun costs 200 bucks! For my money' this is a good gun out of the box, and a great gun after some minor work!


Last edited by Mentolio on Thu Nov 28, 2013 1:40 pm; edited 5 times in total
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PostPosted: Sun Oct 13, 2013 9:06 am Reply with quote
chet
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Contact Mike at Flying Dragon air rifles, he just did one
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PostPosted: Thu Nov 28, 2013 1:32 pm Reply with quote
Mentolio
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I finally got a Chrony Beta, and have done my first series of Chrony testing on the Leverage (and my Vantage NP, covered in another post). This is my first time using this piece of diagnostic equipment, so I'm not 100% on how to interpret all the data, especially how the "Standard Deviation" comes into play, but it seems to me that this gun shoots pretty well.
I shot three strings of ten shots, with three different pellets, going directly from one brand of pellet to the next. The first two pellets are pellets that I know the gun "likes" from target shooting. The third is a wild card that I just received in the mail on Wednesday, and haven't tried for accuracy on a target yet. Test was conducted on Thanksgiving day. Weather was sunny, but cold (about 36 degrees) and windy (gusts of up to 25 mph). The Chrony was set up about 1.5 to 2 feet from the rifle's muzzle. Here are the results:

String #1: RWS Superdome, 14.5gr. Low:721.6 FPS, High: 767.0 FPS, Average: 734.5 FPS, Extreme Spread: 45.46 (not so good?), and Standard Deviation: 12.68.

String #2: JSB Exact Jumbo Express domed, 14.35gr. Low: 708.8, High: 728.3, Average: 714.9, Extreme Spread: 19.5, and Standard Deviation: 5.83.

String #3: H&N Field Trophy, 14.66gr, domed. Low: 694.8 (maybe a bad pellet, as this was shot #9? The rest of the shots were really consistent), High: 719.7, Average: 707.7, Extreme Spread: 24.88, Standard Deviation: 6.7.

Now, the manufacturer (Umarex) claims 1000fps with alloy pellets from this gun (even I know that's crap!), 820fps slinging lead. While I'm not getting too close to 820 even with the fastest pellet I shot, I'm pretty happy with the velocities I got, with at least two pellets that I know I can put on target. If the numbers are any indication, the H&Ns should out shoot both of my go-to slugs, and I haven't even tried the H&N hollow points I got yet! Bear in mind, these numbers are (significantly) on par with what others have gotten, and I'm not even using the stock seal (I'm using a Gamo seal because I couldn't get the right one from Umarex at the time. I've since scored two replacements from Umarex).
I've got about 500 plus shots thru it (and 5 squirrels) since the "lube-tune"/rebuild, and it still smokes like a Frieght train, with most pellets. It seems to smoke the most with JSBs, and the least with H&Ns and Crosman Destroyers...weird...thanx for reading, more to come!
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left "Ole-Faithful" cocked and loaded in the gun l 
PostPosted: Fri Apr 11, 2014 8:53 pm Reply with quote
Mentolio
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Yep, left the leverage cocked in the locker for a few months (after a hunt. Totally unsafe and totally not like me normally). DUMB-DUMB-DUMB!!!!!Sad/Cry So after beating myself about the face and head for awhile, I decided to Chrony the Leverage, if only to compare it to my new Hatsan (and it's own old numbers). My original (post lube-tune and Gamo seal install) included only three pellets, two of which I tested again. My original numbers were: Avg-734.5fps with RWS 14.5 Superdomes, and Avg-714.9fps with JSB Exact 14.35 domes (my most accurate pellet). In my new test, the numbers for these two pellets were: RWS avg-705.8fps, and JSB avg-691.4fps. Not exactly terrible, but a significant enough difference to cause concern, at least for me.
Just to be safe, I ordered a new spring from Umarex for about 20 bucks shipped. I also figured I may as well inspect the Gamo seal, and even though it looked good, replaced it with a slightly larger in diameter Umarex seal (A.K.A.: the RIGHT part).


Here you see my original spring on the bottom, new spring in the middle, and another Chinese spring from Archer Airguns on top (I may try that one someday). While I didn't measure it, the original didn't appear to lose any actual length.

After new seal and spring, my numbers were as follows:
RWS 14.5 Superdomes: Avg-741.3fps (more in line with my original numbers) and for the JSB 14.35: Avg-747.1fps (a significant improvement over both older tests). I fired a total of 75 shots in ten shot strings, with seven different pellets. My average increase was 50fps! I actually got a full ten shot string, all of which were over 800fps with H&N 12.65 hollow points (avg 808fps). Hopefully, the seal finishes breaking in, and some of the Extreme Spreads calm down in the next two hundred shots, or so.
This weekend I'll accuracy test (this gun prior to my leaving it cocked was always pretty accurate). Hopefully, the accuracy is still there, or better.
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PostPosted: Wed Jan 14, 2015 6:48 pm Reply with quote
clgraham82
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Mentolio

Can I ask how you used the spring compressor you built? The crazy end cap makes it difficult to use a conventional spring compressor to get the spring in/out of the gun.
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PostPosted: Wed Jan 14, 2015 8:21 pm Reply with quote
Mentolio
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My first "spring compressor" was simply a steel rod that I heated up and shaped one end into a hook. The other end is threaded. I was able to hook one of the coils, and use the nut and a spacer to pull the spring forward (towards the muzzle) enough to remove the retaining pin, and pull out the rear spring guide and end cap.

HOWEVER

When I pull the gun apart now, I just place the muzzle on the floor and lock the receiver between my knees. Then I just push down (hard) on the back of the rear spring guide/end cap, remove the retaining pin, and slowly let the the spring release. Reassembly is a bit more difficult, but the spring really doesn't have all that much pre-load, so it's doable. I find using a large flat head screwdriver to help push the guide/cap back in (the head fits in that slot, and the handle is more comfortable to push down on than the back of the cap). Even my new spring (which was pretty long by comparison, but has since "shrunk" down to the same length as the old) was done in this way.

Sorry if this is a bit difficult to follow. If you need me to, I'll post some pics demonstrating what I'm talking about when time permits.
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PostPosted: Wed Mar 11, 2015 2:25 pm Reply with quote
humb
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hi
i read that you can use BT9M22-00-5 nitro piston to mod this rifle
i want to buy one and do mod (i live in europe so no mike Sad/Cry )
but this is my first underlever rifle ,and i never did any mods on old ones

so can anyone help
thanks
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PostPosted: Wed Mar 11, 2015 3:25 pm Reply with quote
Robw
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You only have to be concerned with the compressed dimension of the OEM
spring as piston travel will limit the amount of travel of the gas spring.

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PostPosted: Wed Mar 11, 2015 3:53 pm Reply with quote
Mentolio
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Possible, I suppose. Another concern I would have is that the rear "spring block" (part in picture above which has the rear spring guide, curves to meet the stock, blocks the end of the compression tube, and has the bear trap release lever coming through it) is made of crap-tastic plastic. Probably not a big deal to someone who has access to a machine shop and the skills to use it, but not something I could tackle. You'd also have to modify the piston to accommodate the end of the nitro piston. As delivered, it has no recess or dimple to keep the nitro piston aligned. Frankly, after owning this gun for some time, I think your money would be better spent on a different, better-made airgun. The build quality of my Leverage is absolute crap, and so too is the scope (which is now dead after riding on back of another springer for about 100 shots). For what it costs, I'd suggest looking elsewhere. Gamo (ducks after saying it) has an underlever or two, as does Hatsan. I don't believe either is "prohibitively more expensive" than a leverage, and are probably built better.
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PostPosted: Fri Mar 13, 2015 2:05 am Reply with quote
humb
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well my other options are from this one for 235€ to---

first is gamo cfx .22/.117 for a 290€
second is hatsan 150 vortex (np in it) .117/.22 for 390€
third is hw 97k .117/22 for 460€ with nikko sterling air king 3-9x42

i know last is better but way more money
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PostPosted: Fri Mar 13, 2015 3:26 am Reply with quote
Mentolio
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Sorry for the prior negativity. The gun's build quality is poor, but it does shoot pretty well, and also responds well to a lube tune. If you just want an inexpensive underlever, a Leverage may suffice. Depending on your ability and experience with modding/working on airguns, buying this just to put a nitro piston in may be more work than anticipated. That's pretty much what I meant.
Obviously the HW is the top choice, and priced to prove it. Have you also considered the RWS 460 (if available where you are)? Come to think of it, RWS may have more underlever models available, are considered well made by most, and are usually priced significantly lower than HW (tho higher than Hatsan or Gamo).
If it's all about Nitro Pistons for you, you are limiting your options a bit. When properly tuned, a steel coil spring works great (better than a nitro piston in some ways), often makes more power, and is more tune able. Only real downside is that you shouldn't cock it then leave it that way more than an hour or so, or you risk stressing the spring. Best of luck with whatever you decide on.
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PostPosted: Fri Mar 13, 2015 4:29 am Reply with quote
humb
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i got rws 48 and air king scope 3-9x42
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Browning Leverage tune (originally titled Nitro Piston conv) 
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