Airgun => Members Reviews => Topic started by: Novagun on July 28, 2016, 12:34:12 PM

Title: Gamo G Challenger
Post by: Novagun on July 28, 2016, 12:34:12 PM
Gamo G Challenger.

Mr Gamo had a selection of demonstration guns at the WAG shoot last Sunday.
Among them was the IGT G Challenger, a funny looking thing with a pale finished beach stock. I had a couple or more shots and decided I wanted one. Out came the credit card and as soon as I got home and walked in the door – “What did you buy?’ She had been sorting out the bank card on the computer and up popped the bill. She was not pleased but I am so that equals Zero.

The Challenger is really the old CF action that is a BSA but with a gas spring. The same action appears on the CF 30, the CFX the CFR and the CF Big Cat that was made exclusively for Hunting and Fishing. The metal work is not up to Theoben standard by a long shot but still very acceptable.

The Challenger has adjustable butt plate and adjustable cheek piece.  The pistol grip is of the upright style and a good comfortable handful. The forestock is quite bulky but it very quickly establishes itself as a very comfortable stock. The most comfortable of any mid range rifle I have handled and probably the best of any common production gun. It really suits tall people and the look of it grows better with time. It is obviously made on a computer controlled router but very tidy. It is noticeably heavier than the synthetic stocked CFX or CFR. (4.3 kgs with scope compared to 3.7 for the CFX) It is quite a big gun but still light enough to not be fatiguing.

The trigger is called S.A.T. Smooth Action Trigger and that exactly describes it. Silky smooth to use. Not as good as a CFX with a GRT trigger – not as good as a Hatsan Quattro or a Weihrauch Record. Nevertheless it is very good and no thoughts of rushing out to buy a GRT. This trigger is nice to use and generates confidence. There is a long very light first pressure that is good for getting your sight picture and breathing sorted out and then a firm and long second pull, almost a creep. The second stage is adjustable for travel length only and the screw is wound all the way in. Maybe a slightly longer screw would shorten up the pull but I am not rushing out to get one.The trigger is a very safe one and probably influenced by European safety considerations. Of course the standard Gamo trigger blocking safety catch and anti bear trap.

The breach is the rotary BSA type and extraordinarily robust. I can say through years of use and abuse on a CFX. It is just as good and maybe better to use than the sliding breach on an underlever Weihrauch. You have to make sure the pellet is properly seated or the rotary action will crush the skirt.

The barrel I am told is a BSA hammer forged one. WARNING: before shooting clean the barrel. The bore is coated with some rusty coloured coating. At first I thought it was rust because it took solvent and lots of patches to get it clean. Looking down the barrel it looks true with no shadows or marks and good crisp lands. Then on to the muzzle.

The muzzle must be designed by a fashion designer to comply with the latest trend. To me it looks ungainly. The plastic muzzle break is a two part thing with movement between each part with no baffles to justify it. It is a push fit over a splined tit on the end of the barrel and held by a grub screw. The whole thing moves and vibrates on discharge. On top of that the spring loaded cocking lever catch is plastic and sloppy. Not good to have things wobbling about on the muzzle when shooting. The remedy is easy – take it off. I have substituted a plastic clip that holds the cocking lever firmly with no movement at all. The same as on my CFX. The barrel end is tidied up with a plastic cover turned out of Delrin The other advantage is that it shortens the length by about 60 mms. The crown looks neat and tidy and no plans to cut the barrel.
The open sights are the ubiquitous day glow things. The best you can do with them is take the black felt tipped pen to the glowy bits and then they become useable. The open sights gave some intermittent respectable groups in between bouts of dieseling. No smoke but I could smell it. After two or three hundred pellets that is disappearing. The rifle now carries a 3 -9 Nikko Sterling non AO.

This rifle is not powerful. About six foot pounds. Although the cocking effort is light it seems to me to be a bit more than it should be for that modest power. Six foot pounds seems to be a requirement for Germany or the Netherlands so maybe it was designed for their laws. Not a lot if any of these guns are seen in NZ gun shops. Maybe the low power doesn’t appeal to young men. It is certainly not enough for  the ordinary airgun hunter or long range. The recoil is light and sharp and no spring noise, rattle or buzz.
The manual is a really a safety pamphlet and gives little other useful information.

Davey told me that the power is restricted because of a very small ( 1 mm) transfer port in the rotary breach so increasing the power would be a simple matter for  P&N HSS. The other CF guns have no trouble putting out good power but I have no plans for that in the near future.
Accuracy is excellent. Five pellets groups through one hole at 12 metres indoors. It will do this with H & N FTT as long as the shooter points it at the right spot. Easy but the shooter can err.
For someone who has been outspokenly critical of Gamo in the past I have to reconsider because this rifle appeals to me. It is a very good gun that pleases me immensely.

Photo to follow as soon as I remember how to do it.


Title: Re: Gamo G Challenger
Post by: slyrod on July 28, 2016, 02:21:48 PM
Great choice of words enjoyable & imformal read.

At 6-7ftlbs, these would make excellent rifles for testing the correct operation of our field target 'knock-downs'

The styling of the laser rastererd graphics on the beech stock could be detracting for some. Now who of the new WAG owner's will be prepared to 'bog' fill & overspray their stock a Ferrari yellow?
Title: Re: Gamo G Challenger
Post by: Davey on July 28, 2016, 03:01:07 PM
I'll be modding my stock, so I'll be thinking about a respray of some kind. Dunno bout yellow though...
Title: Gamo G Challenger
Post by: Pauly5 on July 28, 2016, 08:18:22 PM
Instead of drilling out the port, just get another and swap them to suit. They come out easy enough.
I think his words were humbly  chosen after being "sprung" by his wife.
Good write up though.

Sent from my SM-G925I using Tapatalk

Title: Re: Gamo G Challenger
Post by: Davey on July 28, 2016, 09:12:30 PM
Problem is the cfx port is the 3.2?mm fac power port. I think we'll need around 2.5mm to get the 10-12ftlb tune.
Title: Re: Gamo G Challenger
Post by: Pauly5 on July 28, 2016, 10:00:56 PM
Fair enough. Could the transfer port be threaded to accept a hollow grub screw? That way you could have different grub screws for different power. It would make it easier to tune by having a range of port sizes. Then if you could be bothered changing it, it would give you adaptability for 10 m targets and then for something like FT, SFT, GST and KFC.

Who will be brave enough to butcher their new gun? Mind you, quite reversible with a new breech.

Does the smaller port provide an air cushion reducing recoil? Will a bigger port create more recoil?
Title: Gamo G Challenger
Post by: swampy on July 28, 2016, 10:48:06 PM
I read in Airgun World that the only things that would change recoil would be changing the weight of the piston, weight of the gun or altering the the spring. Everything else just changes noise and vibration. Don't know if that is true or not from my limited experience.
Title: Re: Gamo G Challenger
Post by: Novagun on July 31, 2016, 05:09:20 PM
Had to try it. I changed the trigger adjustment screw for a slightly longer one and it is just how I want it.
No need to even think of a GRT.
The transfer port - one day but no just yet.

The revolving breach block lends itself to drilling and taping and then having changeable brass inserts of any size that you fancy. The one certain thing that Jim from Airgun World has established is that changing the transfer port size changes more than just the airflow. Piston cushioning and piston rebound are affected and thus recoil.
Title: Gamo G Challenger
Post by: Pauly5 on July 31, 2016, 05:17:48 PM
I hope your trigger is safe though. Don't want a pellet travelling up through the floor from the workshop into the lounge. You'd be in more trouble.

Sent from my SM-G925I using Tapatalk

Title: Re: Gamo G Challenger
Post by: Novagun on August 08, 2016, 06:15:11 PM
Well it didn't last long. Neither the resolve to leave alone nor the Gamo Challenger.

It started to shot erratically and when I tested it on the radiata penetration test it had lost a lot of power so it had to be  the piston seal. I pulled the gun to pieces and sure enough a sliver off the skirt.

Today I went to town and bought a new rolling breach block with a standard CFX transfer port. I forgot to measure the size of the transfer port but about 3mms. I also bought a new Gamo piston seal but in  the end I did not use it. My never humble opinion is that seals for Gamo and Hatsan are too hard. It may be so for most cheap to mid priced guns.

The exercise was a chance to give the innards a good wash out and clean up.
I reshaped a 25 mm hydraulic seal to fit the piston and the compression tube bore and put it back together.
A few pellets to foul the bore a bit and accuracy is back to normal.
It is hard to judge but I think recoil is reduced because the gun is shooting very smoothly. I think the small bore of the original transfer port was causing excess piston bounce.
According to the radiata penetration test power has doubled.

 What next on another rainy day?
Title: Re: Gamo G Challenger
Post by: Novagun on August 08, 2016, 09:20:09 PM
Well maybe not double the power but it has gone up. The radiata test is renown for its varying accuracy.
What is definite is the accuracy and the now very smooth shot cycle.

The next thing is to turn up a piston seal from urethane 90A because I have a little piece and see how that goes.
Title: Re: Gamo G Challenger
Post by: Pauly5 on August 08, 2016, 11:28:15 PM
How is the accuracy? What sized groups are you getting, and is that with a scope or open sights?
Title: Re: Gamo G Challenger
Post by: Novagun on August 09, 2016, 08:36:11 AM
Five shot groups with a hole about 7 or 8 mms. Often single shots through an existing pellet hole. Shooting standing with rest at 12 metres and a scope. The open sights are pretty ordinary and not fine enough and I can't see the single pellet holes without a scope.

I have my share of poor shots but I am certain that is because of the wobbly shooter and not the rifle.
Call in on one of those Pauly5 lunch breaks and have a go.
Title: Re: Gamo G Challenger
Post by: Davey on September 01, 2016, 09:31:52 PM

Here is a photo of Novagun's G Challenger and CFX.
Title: Re: Gamo G Challenger
Post by: Mintie on September 26, 2016, 01:48:54 PM
Had a look at one of these in hunting and fishing today, while it looks nice it is horrifically over priced at $750 imo, and after being ignored for 15 mins in the shop I was out.
Title: Re: Gamo G Challenger
Post by: Novagun on September 26, 2016, 04:24:26 PM
Yes I agree with you $750 is too much for the rifle. At that money one would do well to look at Ron Youngs' catalogue before buying. Those Challengers when they first came out were about $1200 if I remember correctly. They have been about for a while. My barrel date is 2014. I don't think they moved from the warehouse for a long time.

Your note piqued my interest and I looked up the Gun City site. No information on the challenger or the CFX but the spring version of the CFR with standard Gamo trigger and a Gun City scope ( that will be a goody) was priced at $699.00 reduced from $737. Way too dear.
However it must be an interesting rifle. The advertising states.
" Adjustable chin strap"
"CFR exquisite innovation in fixed barrel"
"Rifle in fixed spout"
'Place any shape of pellet or dart , close the barrel" 

Title: Re: Gamo G Challenger
Post by: Novagun on October 13, 2016, 09:15:50 PM
Challenger update.
Well the Challenger shoots very smoothly and is not too bad out to 10 – 12 metres. At 25 metres I found it disappointing. However it knocked over Field targets at 30 to 35 metres but 50 metres was too far. The sticking point was the poor groups at 25.

I found that the only pellets that engaged the rifling on a push through were H&N Field Target Trophy. AirArms (JSB) at 4.52 mms left no rifling mark at all and neither did JSB Exacts at 4.53 mms. From that I conclude that pellet sizes are nominal only.

A while ago I was given a CFX compression tube and barrel dated 2008. A good year I hope. It had to be tried but the SAT trigger set up and the IGT ram does not fit the CFX configuration and the piston sear would not engage the piston on cocking. I needed to shorten the distance the trigger assembly stuck out from the compression tube. That meant cutting the trigger group slot; re-drilling the locating holes in the trigger block and the compression tube and turning up two pins for an interference fit. Good fun if you like tutuing about…
On assembly I put an extra washer (2mms) behind the gas ram. A titch more preload there.

Reassembled it still shots smoothly but the power has gone up a bit. A bit more penetration into the radiata block. I think that comes from the pellet to barrel fit and not much from the extra preload. I will have to bump into the Combro again and measure the velocity. I guess pretty close to 12 ft lbs.
The downer is that the bluing on the barrel had a rust spot and slight pitting. Cleaning it off wore the bluing away. I can’t do anything about the slight pitting but covering it with a bit of black tape disguises it. The bore and rifling looks good and it so far it shoots well.

The IGT powered gun is very nice to shoot. Quiet and smooth.
Title: Re: Gamo G Challenger
Post by: Novagun on November 02, 2016, 09:07:38 PM
Gamo Challenger. The next update.

Well the Gamo Challenger project marches on. I have played with muzzle weights and airstrippers and tried hard to convince myself that it was all pointing to improvement. The decider came last Sunday on the WAG indoor range at 25 yards. Result – the realization that this rifle as it stands is a piece of junk. The only worthwhile improvement so far has been the substitution of the CFX barrel. That was worth doing.  The rifle did not shoot well at 25 yards;  still not bad at 10 metres but really disappointing at 25 yds.

So in my own way I compared what was different between my much butchered CFX and this Challenger that was initially advertised for sale a $1275.00. I jest not because I saw the printed advertisement today.
The difference is the barrel and in my never humble opinion that is a problem. I had been hanging onto the tit on the muzzle because the ½ inch NF thread that I worked onto the muzzle enabled me to swap muzzle appendages as often as I liked. Big mistake.

To explain, and some of this is surmise but it seems logical to me.
The barrel diameter of 16mms OD is turned down to 12.5 mms at some stage during the production of barrel. This turn down is the bit that accepts the plastic CF range muzzle break. There is a spline pressed into the turned down part to stop the muzzle break rotating on the muzzle. That would take some pressure to press in and to stop the thinned down muzzle from crushing there must be a mandrel put into the muzzle to accommodate the pressure. There are marks that could have been made inside the muzzle by the work of twisting out the mandrel. Marks not unlike those that a twist drill would make.

The end result is that the final 25 mms of the barrel has no rifling. A pellet can be dropped into the muzzle until it hits the rifling and then it stops. It can then be shaken back out. The clearance between pellet and the unrifled part is slim, say .5mms or there abouts. That clearance must be such that either the skirt could interfere or the still confined airflow past the pellet skirt could interfere with the clean exit of the pellet from the barrel.  Whatever was happening is not good. I could not see that actual crown of the barrel down the hole so who knows what that was like and I destroyed it.

My remedy was to put a cut off blade into the circular saw and  cut 30 mms off. A chamfer of the muzzle with a twist drill and a polish of the crown with the brass screw.

Result: today the rifle shot one ragged hole groups of 10 mms at 25 yards and it did it three times.
I think, I hope I have got it right this time.

 I am still very happy with the IGT system and the SAT trigger.
I should be disgruntled that I bought this rifle but I am not. It is, in my never humble opinion, a good rifle. I am still very pleased with it and the tuting to get it right adds to the fun but this is not a rifle for everyone.
Title: Gamo G Challenger
Post by: Pauly5 on November 02, 2016, 11:24:20 PM
That's great Hugh. How satisfying to get those results.
Title: Re: Gamo G Challenger
Post by: Novagun on June 24, 2017, 10:09:21 AM
Wet day yesterday so I made an adapter so that the Gamo piston will accept a 25mm Wiehrauch piston seal. There is no doubt that the seal is better than the Gamo version. The sound has changed to a POP noise. Just the same as my CFX .
The weirauch seals are better than my home made ones but much more expensive.
Next thing to consider is either a more powerful gas ram or converting to wire spring.
When firing the CFX then picking up the Challenger, there is no difference in the firing cycle. Of course the
Challenger is heavier but not as powerful.
Both are accurate  one as good as the other. Not surprising really because the Challenger is really a CFX and both with the same modifications.
Title: Re: Gamo G Challenger
Post by: Novagun on June 05, 2018, 07:47:16 AM
The Gamo Challenger marches on. Not the rifle I bought from Mr Gamo. All the Gamo underlevers are fundamentally the same. But the Hammer forged barrel in the Challenger makes it a do not buy rifle.
My Challenger has had a CFX action for a while. I have tried it with the modest Challenger gas ram and a more powerfull one out of a CFR IGT. Now it has a standard steel CFX spring. Actually it has the CFR  mechanism with a steel spring mounted in the wooden Challenger stock. The extra weight of the stock makes it steadier to shoot and the stock doesn't flex like the plastic one. The CFR is the one I have with the barrel shortened about 150 mms.

I like the short barrels and my Webley Tomohawk now looks like a long tom.

Title: Re: Gamo G Challenger
Post by: Novagun on October 20, 2018, 03:22:28 PM
I have had the steel spring in the Challenger for a while now. A GRT 4g trigger now and it is shooting pretty well.  At the small bore range it was shooting just as well as the HW 77. It is a bit lighter than the 77 and I thought there was a suggestion of spring buzz. Maybe that just shakes the barrel a little bit.
Anyway, I have changed back to the gas ram. There can't be any spring buzz now but it is harder to cock. And I think there is no piston bounce as there is with a spring.
Just as accurate on the short range but the next shoot at the small bore range will tell. That will be the first test with the GRT and ram.

Gamos. they get under your skin if you let them.
Title: Re: Gamo G Challenger
Post by: Pauly5 on October 22, 2018, 08:38:16 AM
Kind of like gamo scabies?
Title: Re: Gamo G Challenger
Post by: Dvlnme on October 22, 2018, 10:24:02 AM
this starting to sound like some my projects,that started out simple,yhen went over board very quickly eh!!
 and turned into a major excercise that cant walk away from evan tho you know you proberly should eh!!
 all part the fun messing round with airguns eh!!prob some medical name for this illness many us seem to
 have caught,my prob is i am exactly the same with firearms,so got it twice as bad lol
 cheers mike
Title: Re: Gamo G Challenger
Post by: Novagun on October 25, 2018, 07:59:03 AM
The target test was promising. I think it shoots better than my HW77 but didn't really get a good chance to make up my mind because a couple of visitors turned up and wanted to try an airgun so that was that for the evening.
Title: Re: Gamo G Challenger
Post by: Novagun on October 31, 2018, 11:12:22 PM
Definitely shooting better than the HW77. Much better. Next thing I suppose is to get the HW77 shooting better because it should be better than a Gamo.
Title: Re: Gamo G Challenger
Post by: Novagun on November 09, 2018, 06:16:16 PM
Gamo SAT trigger.

Been a bit wet here for a day or two. Out came the three Gamos. The CFR in the Challenger stock is top of the pile. Shooting very well. Didn't want to touch that. The old CFX in the CFR stock could be a bit better. The  superglue modified trigger is pretty good but not as good as the GRT4 trigger.
I am not importing another GRT, too expensive so I made one.
I cut the trigger blank out of a piece of 6mm sheet aluminium just using a drill and an ordinary coping saw with a standard blade in it. Tidied up the rough blank with files and then sanding out the marks. It came up pretty good but not as polished as a Wingman one. I suppose I could upgrade it with brasso. Maybe next rainy day. I drilled and tapped for the adjustment screw and it works just as well as the genuine GRT. Light with a crisp let off but not really a hunting trigger. Too light for that. The main thing is no creep. That means there is only a small point of contact with the levers.

Just like the GRT4 it is a single stage trigger. I am pondering making another trigger blank but altering the shape a bit and having two adjustment screws. That will turn it into a two stage trigger.  I will get on to it.

The part that I can't reproduce that the plastic and the GRT4 trigger have is a milled keeper on the side of the trigger blank. That indent keeps a pole in place that stops the trigger sear from falling and letting the piston off when the trigger is in the home position. I dont think , well I just can't carve it in by hand so that pole has to be left out. I don't think it is unsafe for a target range rifle as it passes the bump test and wiggling the cocking lever back and forth.

If anyone wants to make a trigger, it is not hard to do. Just measuring, marking and cutting. You do need about three or four different files. A least a flat bastard medium cut and a couple of rat tail files. Some 180 grit and some 220 grit aluminium oxide sandpaper and a drill. A drill press is best but a pistol drill will do.

Tonight I will take the trigger out and do a bit more filing to get the safety catch to work. Don't know why I will because I never use a Gamo safety catch as the design is pretty crude and not reliable for a finely adjusted trigger.

PS. I still haven't learnt the photo procedure..
Title: Re: Gamo G Challenger
Post by: Novagun on November 12, 2018, 08:06:47 AM
The planed two stage trigger is not going well. So far my drawings have not come up with the answer.
 Even a rough mock up doesn't work with the Gamo trigger levers.
Should have realised that in the beginning. That is why the Charlie da Tuna GRT trigger is single stage.
Title: Re: Gamo G Challenger
Post by: Dvlnme on November 12, 2018, 09:49:52 PM
i got your email Hugh,we need have a talk on fone,couple things you wrote slightly out of context,we need
 sort them out,then its all good for the sticky mate.
 cheers mike
Title: Re: Gamo G Challenger
Post by: xyon on January 11, 2019, 12:48:14 PM
The planed two stage trigger is not going well. So far my drawings have not come up with the answer.
 Even a rough mock up doesn't work with the Gamo trigger levers.
Should have realised that in the beginning. That is why the Charlie da Tuna GRT trigger is single stage.

The Charlie da Tuna GRT trigger is a 2 stage trigger.
Title: Re: Gamo G Challenger
Post by: JS on January 15, 2019, 02:04:20 PM
The planed two stage trigger is not going well. So far my drawings have not come up with the answer.
 Even a rough mock up doesn't work with the Gamo trigger levers.
Should have realised that in the beginning. That is why the Charlie da Tuna GRT trigger is single stage.

The Charlie da Tuna GRT trigger is a 2 stage trigger.

Does anyone know of an adjusting guide for the GRT III trigger blade for 2 stages? I admit I havent played with mine mich, but on install it was crisp single stage. A lot better than the unpredictable factory trigger but room for imporvement..
Title: Re: Gamo G Challenger
Post by: xyon on January 15, 2019, 11:57:35 PM

From the CharlieDaTuna web site. (
Title: Re: Gamo G Challenger
Post by: Novagun on January 20, 2019, 10:08:08 AM
Yes Xyon. You are right, I looked at the web site. The GRT111 is an adjustable two stage and that works well on the old steel trigger Gamos. The GRT4G is not adjustable and the first stage built in to the trigger blade. In my gun that part does not work well but the second stage is very good.
As a two stage trigger it is not as good as the Record trigger.
With the Gamos I have the triggers are set so they work as a single stage. I prefer that and not worried about two stages. A good single stage works very well.