GAMO 126

Why is the Daisy/Gamo 126 (126) Known as a “Hangar Queen?”  Because after a while it will lose power and the owner will probably send it in for repairs or stop using it – planning on sending it in for repairs.  This is really too bad as these are very fine 10 meter rifles and deserve to be used.

What is happening to cause this?  This was my question! As I have two 126’s – one is a beater and one is Like New In Box, however each would shoot my lightest pellet (6.8 grain GECO) at about 450 ft/sec.  No where near the advertised 585 ft/sec (180 m/sec.)  There is a lot of information out there, almost every bit of it that I got (dirty valves, weak spring, (spring?) low on oil, (oil?)) was wrong!  I probably just didn’t ask the right person. However, thanks to Mitch Haley who just bought a 126 and wanted the answer to the same question, I think that we have come up with the correct answer:

(The first thing to do is check your seals – cock the rifle let is sit for about an hour and see if it still shoots at about the same speed – if it does than the rest of this article applies – if not try to get new seals and see where you are.)

The first thing that you should know is that the 126 is a single stroke pneumatic and gas ram hybrid!  This is important – inside the piston that you push down with the cocking lever is a second “booster piston” that is

actually a gas ram.  Here is the problem, as the pressure behind this “booster piston” bleeds down your power falls off.  We calculate that Mitch had about 50 psi behind his piston (estimated fully charged 600 to 750 psi.)  At this point his rifle would shoot a Meister 7.7 at about 410 ft/sec.  He could push his piston in with his fingers – I couldn’t push mine in, but obviously mine wasn’t up to full pressure either.

What can you do?  If it is still holding some pressure perhaps it doesn’t need to be completely rebuilt – just recharged.

If that is the case then there is another way to restore at least some of the power: I think that the “original” 126 was designed to be self charging for its gas ram** and that it probably shot about 550 ft/sec on the Gamo “marketing pellet.”  But at some point they started coming back with problems due to the “booster piston” getting stuck because of dirt and since they would only shoot a real pellet at around 500 ft/sec the marketing department wanted more oomph (remember this is all speculation on my part – but it makes a good story.)

The answer to both problems was to add a “dust cover” on the front of the piston and to precharge the “gas ram.”  They made this “dust cover” out of the same stuff that they made their seals out of (its red whatever it is) and it worked well – in a sense too well as it won’t let any of the high pressure air in front of the piston get to the rear seal and self charge the “gas ram.”  But the guns were sold, there were few problems, then they stopped producing them. After a few years pistons started coming back for repairs as the guns were losing power – well fine, “rebuild the pistons.”

Could it be this simple – the dust cover is keeping the gun from recharging its “gas ram?” To prove this theory to myself I decided to remove the “dust cover” and try to shoot the gun to see what happened.  The first shot (6.8 GECO’s) was all the way down at 378 ft/sec.  I was sure that I had really broken something this time (it was the beater, of course.)  The next was 400 ft/sec and gradually it worked its way (about 20 shots) up to 520 ft/sec.  Here it has leveled off.  I was elated and confident enough about the above theory that I was willing to go on record with this article.

The next thing to do is put The dust cover back on – this turns out to be a very good idea as after about 100 shots there was a dirt ring begining to build up on the piston and you gain another 5 ft/sec (probably by filling in some air space.)  I have since gotten some H&N match pellets and this rifle shoots them exactly the same as the one reviewed in the Airgun Letter (avg. 515 ft/sec.)  Interesting.

Later I might try putting the piston is a pressure chamber to boost its pressure up to factory specs (whatever they are? it will be trial and error as I don’t think that Gamo is going to tell me – they have a steady income stream rebuilding pistons.)

I only have one data point so far, as when I tried to do my other rifle (LNIB) I found that that it was put back together by “Godzila the Hun with Air tools.” After working though all the slotted screws that were stuck tight without damage, the screw in the piston turns the piston instead of losening – so I have put that rifle aside for a while.  These screws only need to be firmly snug – there is no great stress on any of them in the rifle.

** Once we figured out that the piston contained a gas ram – the question was how did they charge it.  There are no holes for a valve.  The answer was that the seal worked as a “one way” valve and the gas in the gas ram would equalize to the pressure in front of the piston if not for the “dust cover” (the owners manual has what must have been an “original” drawing of the “works” as the “dust cover” is not shown.) So to charge the “ram” the piston would be put into a pressure chamber that is then pumped up to the required pressure.  Then the “dust cover” attached and the piston installed.  (There is a business here recharging 126 pistons at say $10 plus S/H – maybe when I get my “pump” and find the necessary parts – naaa!)

HTH  Jim P.

If you decide to try this.  Here are some notes that might help you.

Disassembly Notes:(This is what I have learned from experience – not necessarily the “only” or “right” way to do it.)

(No guarantee is stated or implied that these are complete or accurate as typed! check before you do something that looks stupid.)

(If I have to tell you, “make sure that the gun is not pressurized or loaded,” don’t go any further!)

IF YOU ARE NOT COMFORTABLE DOING THIS KIND OF WORK – DON’T DO IT!

1. Remove Rear Sight
2. Remove two “Cocking Block” Mounting screws (under rear sight)(4mm Allen key.)
3. Remove Stock – the two big slotted screws (Craftsman 1/4″ slotted head at least.)(Gunsmith Screwdrivers are prefered!)
4. Remove Rear Trigger assembly:(order is important as stud acts as lock to screws I’ve found)
5. Remove hollow stud behind the trigger that  the rear stock screw went into (10mm open end wrench.)
6. Remove Two slotted screws on sides (Craftsman 1/8″ slotted head at least.)

Note: none of these should be too tight just firmly snug when reassembled.

1. Trigger assembly will “unhook” from trigger bar (the long connection to the front trigger assembly).       Look at it and remember how it goes together (or make small diagram.)
2. Remove Rear trigger Block – this is the about 3/4″x1/4″x1/8″ plate that the two trigger screws went into it.  It is held in place by a Philips head screw into the Cocking Block (#2 Philips)

Note: Relieve pressure on Cocking block by partially opening the cocking arm.

Note: If you are doing this in order the screw will be snug (If not it will really be locked in there! by the screws on top.)

Note: Now the Cocking Block is able to slide out – and if you are careful (especially when putting things back) the piston can be removed at this point.

5a. You can now carefully lift the “trigger bar” (the connection from the front to back trigger sections) out of the slot when ever it is blocking the movement of the slide.

6. Slide the Compression tube back so that the first hole towards the barred reveals a screw above the latch pin. Remove this cover screw (1/8″ slotted head.)*  Now slide the Compression Tube forward until the little hole on top of the pin is revealed.  Get something that will push through this little hole and push the pin down to release the latch lever.  There are three parts here held in by the pin the latch lever the latch block and a spring in a hole behind the latch block.  When you get the whole assembly out (later) get real familiar with how this works as this is the “fiddly bit” about getting things back together.  You just need to remove the latch lever at this time (pin block and spring can stay in.)

*I now know that if you have an early model there is only one piece and no hole on the top – easy to get out – really dificult to get back together.

7. Slide the Compression tube back a little further and the valve will pop out through the appropriate hole.  Two parts a valve and a spring.  The spring tapers down to the valve (if they don’t come out together.)
8. Slide the Compression tube further back and you will be able to unscrew the “guide screw” a slotted screw machined flat on each side (3/16″ slotted head.)

Note: this screw is just tightened until it is snug then backed out to align with slot when you put it back in.

9. Now the whole Compression Tube assembly will slide out.

Reassembly is the reverse.

On the front of the Piston you should see a “white washer” with a slotted screw in the middle.  This is front of the “booster piston.”  If you can push this in – you are really low on pressure in your “gas ram.”  I calculate that it ought to take roughly somewhere about 330 lbs. of force to move this piston in if it is fully charged.

To do the modification (removing the dust cover) mentioned above unscrew this screw and gently work out the “white washer” and a “red seal.” Leave the “red seal” (dust cover) out and put the white washer and screw back.  Reassemble your rifle and shoot it.  It should recharge and the velocities should rise up to a point then level out. Then do the whole thing (at least down to 5) and put the “red seal” back – it does keep the dirt out and fill airspace.

Hope everyone that read this far found this interesting.

Jim P.

I have two of the Daisy/Gamo 126’s and as an under $400 10meter gun it is in a league by itself. I agree with everything that has been said about cocking the rifle – I try to hold it vertically in front of myself and press the lever together with the stock close to my chest – it is like some of the old exercise equipment.  If you do it some of the other ways you will start to get a case of “Gamo elbow.” (doing it “my way” may build up my “abs” (yea right!)

Note that I called mine a Daisy/Gamo.  There evidently are at least two (maybe more according to my new Airgun Digest 2nd edition(AGD2) – thanks Cliff ) models out there.  The Daisy/Gamo 126 has Daisy written on the accessory rail – the Gamo doesn’t have an accessory rail.

The Daisy has a Walther barrel of blued steel – the Gamo has the Gamo barrel with a plastic sleeve (this is not as bad as it sounds, because these rifles are often handled by the barrel and this sleeve prevents rust.  The AGD2 indicates that there are variations based on the stock and barrel weights for running target and some other disciplines – I haven’t heard of any of these for sale. Other than the ergonomics of the cocking – the stock looks chunky, but feels great.  The accuracy is there – it is a 10 meter gun.

And the trigger – is excellent!  Triggers are different, but this one is world class in it own way. ( Tom thought so too. – so it is not just me.) If you were to buy one and find that it doesn’t shoot light pellets in the 500 fps range I’ll send you “Secrets of the 126″ to explain why and what you might be able to do about it.  e-mail me.

I think that the 126 is a far better start into 10 meter than the Daisy 753 etc. Just my opinion.

Jim P.

 

I posted this about year ago. To date over 1000 rounds stiil going. By the way Spain is not rebuilding the piston anymore thus the no fix. I’m currently working with Paul Landrith on a fix for the pistons. These mods were over a two week period.

Lob’n Lead

CJ

Okay,The valve and all the seals were bad so I called John Groenwald and Tom Landrith. After picking each one’s brain {by the way Tom seems to know his stuff the best}I went to work. First was to make a new valve which I made out of brass with o-ring seals. The original was hardened steel with urethane seals. That didn’t set well as as the vavle rubs the gun housing I’d rather have the valve wear out than the housing. Next was the piston, taking the piston apart I found that the design could be improved I mean why worry about three seals to wear when you could get rid of one. So my gasram pnuematic is now a springram pnuematic.

Making a part out of delrin and putting a light die spring in place of the gasram . Now for the tricky part the springram seal, I used a .750 brake cylinder cup. I made another delrin part that fit in the center of the cup and held it place with a flat head screw. The only part I couldn’t make was the outer seal on the piston which I ordered from Tom Landrith $4.50 a seal plus S&H . Chrony results were lower than expected but I should be able to bring up the FPS by preloading the spring some. I wanted to have about a 450-475 FPS but the extreme spread is low which is great. Here’s the results the next set will come after more preload Tuesday.

Geco’s 6.8gr

399

395

397

394

401

402

404

397

393

396

Club10 7.0gr

398

392

382

398

396

395

396

402

403

399

 

CP’s7.9gr

385

386

385

388

383

391

386

390

384

389

Well here’s my recent try to get my Gamo 126 shooting right and it looks like I got it this time. So let me tell you what I did. Two people had told me that these pistons were full of oil which in my mind defeated the purpose of the gasram piston. Then when Jim Partridge told me a friend of his filled his piston with oil and his was shooting at 510 I got to thinking. You can’t compress a liquid. If this was a bad design and they couldn’t get the guns specs up at the factory they may have made some mods for production. Making the piston solid {no gasram}.By filling the piston with oil would effectivly make it like that. So what I did was to make a slug out delrin to fill the void and put a O-ring seal at the ID step in the piston. Cocking effert went up quite a bit and after shooting it 20-30 times I went to the Chorny. The results were better that I excpected. Here they are { all 20 shots went into .500 at 15yrds}

Geco 6.8gr 10 shot group

+ 497

– 488

AVG 492

ES 9
STDV 3.7

CP’s 7.9 10 shot group

+ 475

– 466

AVG 472

ES 9

STDV 2.6

Ok, this is the last mod for a while. If you’ve read the post in the past you know that I’ve been trying to bring my Gamo 126 up to factory specs without factory parts. The last piston I made I left a 1cc area for the air to compress in the results were good with a max FPS 497. This is about 100fps low to the factory specs which claim to be 150m/s or 590fps. After some thought I convinced myself that the 1cc area was to much so I got a wild hair and made one more piston insert. This one is slip fit and flush to the top of the piston. After installing it I didn’t know if the main cup seal would hold wich it did cocking effort went up quite a bit enough that after about 40 rounds it was rest time. It’s still one hole groups at 10m and makes a little more noise. The bottom line though is that I made it to the Factory specs and a litte over. Here’s the results of last the Chrony.

Geco’s 6.8

avg 589

+ 597

– 585

ES 12

SDEV 4.27

CP’s 7.9

avg 557

+ 562

– 550

ES 12

SDEV 4.18

CLUB10 6.9

AVG 575

+ 581

– 565

ES 16

SDEV 5.38

 

All,

I purchased another Daisy/Gamo 126 and have learned a little more about this fine target air rifle.  I purchased the rifle in non-working condition so I was not disappointed that it wasn’t functioning when it arrived ( I was surprised later at how bad the non-working was – but initially) I was very pleased by the appearance of the rifle. The new knowledge that I learned as I began to work on this rifle is that evidently in the production of the 126 there was an upgrade – i.e. a minor change in the design. This 126 had a serial number beginning with 848xxx (I’ll call this Phase I.) My other two have serial numbers 1194xxx and 1105xxx and they are for all practical purposes identical (Phase II.) The differences that I noted were:

Phase I, Blond Stock and red rubber butt pad. Phase II Dark stain with black rubber pad.

Phase I, has no small (1/16″) hole in the top of the compression tube – About 1/4” back and on the right hand side.  The reason for this is that the Phase I has a single piece screw/pin that holds the compression tube catch in place – this is very difficult and fiddly to get back together. Phase II has two pieces a pin and a screw to cover it (the hole is so you can push the pin out) this actually makes it a little easier to get the thing back together.

Phase I has a white nylon adjustment screw ahead of the trigger – Phase II a black steel screw.  I’m not sure if there are other differences in the trigger mechanism – superficially it looks like there are (I didn’t get into it.)

Phase I has the machined flat for the front trigger assembly extending all The way to the hole for the front stock screw.  Phase II the flat is just for The front trigger assembly (I can’t see why it was made like that in the first place – but who knows.)

When I operated the Phase I gun it was extremely smooth – the Phase II guns Are somewhat tinny and a tiny bit rough.  The reason for this became obvious as I disassembled my new (Phase I) gun – all the internals are coated in what appears to be 30 weight motor oil (Phase II is essentially dry.)  The condition of the screws and bluing convince me that this may be original to this rifle. And herein lay part of the problem – over the years this oil has degraded all of the seals in the gun to the point where they would barely hold together and were somewhat gummy.  Of course the “gas ram” in this 126 was not holding any pressure as its seals had degraded also.

There were other problems with my new (Phase I ) gun – but they were due to improper repairs.  Someone in the history of this gun had bent the mount for the forward and rear trigger assembly and had really scored up the release valve ( I haven’t determined if there was any other damage.)  Because this gun had a very nice stock and excellent bluing and one of my other 126’s was sort of ratty in appearance (but shot very well) I made my final discovery.  All the parts are interchangeable.  I swapped the front and rear trigger assemblies and the entire compression tube / compression lever from the ratty Phase II to the receiver and stock of the Phase I.  It works beautifully and looks great.  I will slowly accumulate parts and rebuild the other rifle for my own education.

Oh yes one final thing the Walther barrel under the plastic sleeve is properly blued.  The “new” rifle came without the sleeve and sight – but the barrel looked so nice and I wanted to scope it any way that I have left it exposed ( I think a nice muzzle weight will just finish it off.)

Just in case anyone was interested.

Jim P.

Return to TenP Files Index