Username:

Password:

Author Topic: Gamo Hunter 440 Tune / Modification  (Read 697 times)

Offline JS

  • Full Member
  • ***
  • Posts: 191
  • Age: 36
  • Location: Auckland
  • Mana 7
    • View Profile
Gamo Hunter 440 Tune / Modification
« on: October 17, 2018, 12:12:00 PM »
So my .22 Gamo 440 sux..

Its 1996 model, a hand me down in pretty good condition with minimal use.
It shoots 3" groups at 25 yards, and that is prone / rested!
I have tried a few pellets and none are any different.
Currently running just under 16fpe with H&N FTT 14.66gr, spread of 15 over 6 shots could be better.

It doesnt get used, which is a pity for any airgun, so the aim is to get it shooting better.  If I fail then it just goes back to sitting in the safe as before.. no harm done.

Step 1:
Swap to the GRT-III which instantly gave a better feel to the terrible standard trigger. At current adjustment it is fairly crisp single stage, but I will have a tinker to see if I can get it better.



Step 2:
The end of barrel has a clear space with no rifling and the rifling didnt look very well finished inside, so the plan was give it a recrown with my professional recrowning tool (Hacksaw).



luckily under the plastic front sight there is a reduced section that acts as a nice trimming guide, losing only around 5mm of current rifling.



After a bit of careful filing then sanding, it is as flat and square as my hands and tools can get it.




It will get a final flat polish and finish the crown with the old brass screw and grinding / polishing compound once I can get some, then probable some cold blue.

Next steps are to install a new spirng with polished ends, new seal which I have on hand from Ausy, new breech seal and polish inside.. Ideally I will get someone to machine a tight spring guide, top hat to try and remove the buzziness and a couple of washers to try and get it around 18fpe.
« Last Edit: October 25, 2018, 11:08:04 AM by JS »
TX200 MKIII .177
Gamo Hunter 440 .22
Feinwerkbau 300s .177
Weihrauch HW80 .22
HW45 .177

Offline Pauly5

  • Hero Member
  • *****
  • Posts: 1887
  • Location: Porirua
  • Mana 28
  • Go ahead, make my day!
    • View Profile
Re: Gamo 440 Sux... for now
« Reply #1 on: October 17, 2018, 11:12:01 PM »
Hey, cool project. I bet it will shoot better after the re crown. I like those photos too, with all the nitty gritty bits in focus.
Will wait patiently for the next chapter.
HW98
HW97k
Tx200
S510
HFT500
Bobcat
Matador R2.5
HW40 (copy)
Daisy 953
P-Rod
1377
Zoraki 22

Offline Dvlnme

  • Sr. Member
  • ****
  • Posts: 395
  • Mana 4
    • View Profile
Re: Gamo 440 Sux... for now
« Reply #2 on: October 18, 2018, 06:57:40 AM »
allways cool to try bring an old gun back into useful service again,had same muzzal issuse with a gamo
 barrel while back did same as you,fortunatly i got lathe so made recrowning bit easier,handy tip for doing
 crown by hand,use tube cutter to cut nice square mark around barrel that you can see and follow with
 hacksaw n files,if cut second mark slighly behind first will give nice square mark to file a bevel to,marks
 only got be just enuf to see clearly,done this many times,n usually works very well.
 cheers mike

Offline JS

  • Full Member
  • ***
  • Posts: 191
  • Age: 36
  • Location: Auckland
  • Mana 7
    • View Profile
Re: Gamo 440 Sux... for now
« Reply #3 on: October 18, 2018, 09:02:17 AM »
allways cool to try bring an old gun back into useful service again,had same muzzal issuse with a gamo
 barrel while back did same as you,fortunatly i got lathe so made recrowning bit easier,handy tip for doing
 crown by hand,use tube cutter to cut nice square mark around barrel that you can see and follow with
 hacksaw n files,if cut second mark slighly behind first will give nice square mark to file a bevel to,marks
 only got be just enuf to see clearly,done this many times,n usually works very well.
 cheers mike
Cheers, yeah seems a pity for any rifle to sit at the back of a safe.
The tube cutter is a good idea. Good thing about the gamo is the front sight has a section where it reduces, and has a nice square rim to work to. Just have to try and file carefully up to that point. we will see how she goes..
TX200 MKIII .177
Gamo Hunter 440 .22
Feinwerkbau 300s .177
Weihrauch HW80 .22
HW45 .177

Offline Dvlnme

  • Sr. Member
  • ****
  • Posts: 395
  • Mana 4
    • View Profile
Re: Gamo 440 Sux... for now
« Reply #4 on: October 18, 2018, 10:17:38 AM »
you know the old saying eh!if not broke keep fixing it till it is,lol
 cheers mike

Offline Novagun

  • NZ Airgun
  • Hero Member
  • *
  • Posts: 870
  • Mana -9
    • View Profile
Re: Gamo 440 Sux... for now
« Reply #5 on: October 18, 2018, 11:59:55 AM »
Looks good so far. Haven't played with one of those for a long while. If I recall accurately, the pivot pin washers in those are plastic and might be worth looking at. From what I can see the gun looks to be in good condition.

Offline Dvlnme

  • Sr. Member
  • ****
  • Posts: 395
  • Mana 4
    • View Profile
Re: Gamo 440 Sux... for now
« Reply #6 on: October 18, 2018, 07:30:36 PM »
you must be to replace the bushings with new ones,maybe even machine up some outa hard wearing
 nulithen from old suspension bushing etc,prob get new factory bushs any way from Ron Young for very
 little and can allways replace spring with gas ram from Alex at magair and have him set it to what ever
 power level you want.
 once i start projects like this it allways ends bad,coz never seem to know when to stop,so they get outa
 hand eh!!!i just hate having guns laying around in safe doing nothing coz need work,so got to tinker with
 them,its like having nice classic car in shed,that i cant drive,coz not going for some reason i can sort out,
 gets me so got sort it out.i allways seem to have a few guns stuck in corner of workshop,have picked up
 cheap some wear,that need bit love n attension and if dont will find one to pull apart just see if it does
 need a bit a tune up etc lol.
 cheers mike

Offline JS

  • Full Member
  • ***
  • Posts: 191
  • Age: 36
  • Location: Auckland
  • Mana 7
    • View Profile
Re: Gamo 440 Sux... for now
« Reply #7 on: October 25, 2018, 10:19:17 AM »
Had a couple of spare minutes so gave the new spring a good polish on the ends. From factory it is not perfectly square so may give the ends a tweak once I can get spring guides machined...



Found myself a precicion crown honing device (brass ball knob from a latch), sanded off the lacquer and used some fine polishing compound to start the crown.. I can see why a screw is used (couldnt find any), as the slot would hold the compound where a ball cant.. Another member mentioned the idea of valve grinding paste - this may work better as the paste would remain on the surface better than a harder compound..



After a few minutes, the crown was starting to appear, and was fairly even...
There are some small burrs internally on the crown which I am not currently sure how to remove - maybe another go with a different compound or paste...
And yes, I slipped and dinged the edge of the barrel face.. I can always file back and start again if i need.

TX200 MKIII .177
Gamo Hunter 440 .22
Feinwerkbau 300s .177
Weihrauch HW80 .22
HW45 .177

Offline Dvlnme

  • Sr. Member
  • ****
  • Posts: 395
  • Mana 4
    • View Profile
Re: Gamo Hunter 440 Tune / Modification
« Reply #8 on: October 25, 2018, 07:03:08 PM »
good to see you making progress,crowning barrels allways slow job doing it by hand this way,but patience
 allways pays off,i no longer crown barrels this way even in lathe,i now cut recessed target type crowns
 on the lathe only,these finish to sharp edge on rifling recessed back approx 5mm from muzzle,so impossible
 to damage them.biggest cause damage to airgun barrels is using the pull thru cleaners many use actually
 cutting a groove in soft steel used for airgun barrels,this was biggest cause crown damage done to
 older militry rifles by the issused pull thru cleaning system with older rifles like 98 mausers and enfields
 has same effect with air guns,better to clean break barrels from breech end with a rod,co2/pcps with
 breech that cant been cleaned from breech,better cleaned with rod from muzzle using a brass muzzle
 bushing to center rod in barrel and protect the crown.trouble with pull thru string type cleaners is its
 allmost impossible to pull one thru without the string rubbing on the muzzle,in time this ruin the crown.
 have cut many barrels exactly as you have done in years gone by,and crowned them same as you doing
 with perfectly good results,but would never do one my super accurate pcps or firearms that way today
 as just not possible to get crowns accurate enuf for these types guns,if you ever need crowns cut super
 accuratly just pm me and i will machine them for you for free just cost you the freight etc.
 got couple old springers laying under the bench here if anyone wants them for project,or parts etc.dont
 know what make they are but not gamos.
 chhers mike

Offline JS

  • Full Member
  • ***
  • Posts: 191
  • Age: 36
  • Location: Auckland
  • Mana 7
    • View Profile
Re: Gamo Hunter 440 Tune / Modification
« Reply #9 on: October 27, 2018, 03:59:18 PM »
Yeah I would certainly not attempt something like this on a serious rifle, this was more a hacksaw and file type diy project. But the offer of a target crown is tempting!
TX200 MKIII .177
Gamo Hunter 440 .22
Feinwerkbau 300s .177
Weihrauch HW80 .22
HW45 .177

Offline Dvlnme

  • Sr. Member
  • ****
  • Posts: 395
  • Mana 4
    • View Profile
Re: Gamo Hunter 440 Tune / Modification
« Reply #10 on: October 28, 2018, 05:16:50 AM »
unless muzzle crown really worn n damaged either damaging projectile or deflecting it to one side,most us
 never guna know the difference,i dont believe that a crown thats not perfectly square makes much
 difference as long as projectile consistantly going in same direction,most wont even notice as long as we
 can calibrate the sights to match,but if its damaging the projectile so it dosnt fly consistantly in same
 dirrection,then we will notice,the whole point of crowning the muzzle is to get end the rifleing as square as
 possible to the bore and rifling ends as clean cut as possible to prevent damage to projectile so it consistly
 flys straight and true.most damage to muzzles caused by bad barrel cleaning technecs damaging rifleing
 by pull thrues/cleaning rods rubbing the rifleing and wearing it in some way, very easy to ruin soft steel
 used in airgun barrels by bad cleaning methods,i very rarely clean an airgun barrel,and when i do i very
 carefully use a cleaning rod with brass bushing in muzzle to prevent rod from contacting the rifleing,the
 same as do with a firearm,i wont use the pull thru many airgunners use, too easy to damage the barrel
 with a pull thru.
 keep up the good work,be worth while when done and put another oldy back into use again.
 cheers mike

Offline Novagun

  • NZ Airgun
  • Hero Member
  • *
  • Posts: 870
  • Mana -9
    • View Profile
Re: Gamo Hunter 440 Tune / Modification
« Reply #11 on: October 28, 2018, 08:39:11 AM »
The advertising pictures for the 440 show a nice looking traditional style rifle. I guess yours is like that. Looks worth putting a bit of time into getting it shooting well.
One unsolicited piece of advice that might ignore or not. The front stock screws are angled through the wood to the tube in such a way that there is not a lot of timber to take  the screw tension. Then Gamo use star washers to stop the screws coming lose. The washers chew into the wood just where you don't have much to play with.

I suggest that you do away with the star washers and substitute small rubber washers, the ones that come on hex roofing screws are perfect. Careful not to overtighten because the timber can split and it that happens there is very little wood to effect a repair.

The hex roofing washers just don't let the screws come lose.

Offline Dvlnme

  • Sr. Member
  • ****
  • Posts: 395
  • Mana 4
    • View Profile
Re: Gamo Hunter 440 Tune / Modification
« Reply #12 on: October 28, 2018, 10:40:17 AM »
just done that exact same fix to a bsa super sport,for that same reason,the roofing washers work very well
 keeping screws from shooting loose and put nuf tension on to keep everything tight into the wood.
 have needed sort this one out few times,usually the owner broken the wood,thats bit harder to fix.
 cheers mike

Offline JS

  • Full Member
  • ***
  • Posts: 191
  • Age: 36
  • Location: Auckland
  • Mana 7
    • View Profile
Re: Gamo Hunter 440 Tune / Modification
« Reply #13 on: November 05, 2018, 01:31:38 PM »
The advertising pictures for the 440 show a nice looking traditional style rifle. I guess yours is like that. Looks worth putting a bit of time into getting it shooting well.
One unsolicited piece of advice that might ignore or not. The front stock screws are angled through the wood to the tube in such a way that there is not a lot of timber to take  the screw tension. Then Gamo use star washers to stop the screws coming lose. The washers chew into the wood just where you don't have much to play with.

I suggest that you do away with the star washers and substitute small rubber washers, the ones that come on hex roofing screws are perfect. Careful not to overtighten because the timber can split and it that happens there is very little wood to effect a repair.

The hex roofing washers just don't let the screws come lose.
Yes its pretty standard looking sporter rifle, no plastic like the modern gamos.
Its still fairly plain to look at - much like a crosman optimus or similar.

Good tip re washers - they do look like micro saw blades that will eat through wood each time you tighten them. I guess they needed something as the buzzy action would probably vibrate them loose if they were flat. Will have to try the rubber washer idea.
TX200 MKIII .177
Gamo Hunter 440 .22
Feinwerkbau 300s .177
Weihrauch HW80 .22
HW45 .177

Offline xyon

  • Jr. Member
  • **
  • Posts: 50
  • Location: Canterbury
  • Mana 1
    • View Profile
Re: Gamo Hunter 440 Tune / Modification
« Reply #14 on: January 11, 2019, 10:10:19 AM »
Did you finish your Gamo 440 project? I remember you mentioned you had one on kiwi airgunners when I posted about restoring my one.