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Project R-77

This area is for the discussion of BB or airsoft sub machine guns, and or other small arms such as pellets.
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Project R-77

Unread postAuthor: )DEMON( » Tue Oct 02, 2007 1:13 pm

Hay everyone.

I have decided I want to play airsoft. But I have no airsoft guns, so what can I do? Well, I just happen to have a pellet revolver but it is .177 cal and I need it to be 6mm for airsoft.

So basically what I am undertaking now is to convert my Gamo R-77 combat revolver from .177 to 6mm.

This will not be easy.

However, the most difficult part will be boring out the existing crappy stainless steel rifled barrel to make way for the new 6mm aluminium barrel.

So lets look over what I am going to do:

-Replace existing .177 cal barrel with 6mm barrel
-modify the cylinders from .177 to 6mm
-Use a much longer barrel when replacing old one
-Extend gun to be as long as the barrel
(using epoxy putty)
-Extend top weaver rail to be as long as gun
-Add bottom weaver rail
-Add some sort of seal between the valve and the cylinders
(possably adding orings around each cylinder)
-Fix 12gram seal on valve

Ok, doesn't seem so hard, lets look at what I already have
Image
Yep, most of what I need. All I need to get is more rails and a BB 6mm barrel, which I will get from my freind, I already have a barrel but that only is long enough to replace the cylinders. I also need epoxy putty, which I will get from the shop.

First of all, Replacing the .177 cylinders.
Now, this will be fairly easy and straight forward. This is because of the actual cylinders. It isn't one piece, its two, a piece which holds all the cylinders and a piece that fits over it like a shroud.
Image

First thing to do is cut the cylinders off the plastic back piece, so they are flush with it, then bore out the existing holes on that to make room for the new cylinders ( about 8mm in diameter). Then Drill bigger holes in the shroud, here are some pics to make it more clear:
Back piece with cylinders
Image
Shroud:
Image

So, thats done, now the hard part.
Boring out the existing barrel. This will be tricky, and I don't think I can do it cleanly myself so I am thinking of sending it to my freinds dad, who is a machinist and have him bore out the old barrel to 8mm. So I can insert and glue in the new barrel.

I will replace the old barrel with a fairly long barrel, maybe about 20cm or so, about 17'' I think. Then the barrel will be sticking out like this:
Image
Which is not going to be very astetically pleasing, so I will mold epoxy putty around the new barrel, extening the lines of the gun and adding weaver rails to the top and bottom. I might just not stick to the lines of the gun and add a little more meat to make it look more agressive. The epoxy putty is very very strong, I do not have to worry about it breaking.

That should just take a lot of sanding to get right, I already have plans. Then I will strip the gun, sand it and add a kick ass black paintjob.

The weaver rails will make it possable to add a lot of accesories.

Another thing I would like to try do is add hop up. This will be tricky but I think I have a simple solution that will serve two purposes. I will add strip good quality tape of some sort to that inside of the cylinders at the furthest most point away from the middle of the cylinders or in other words, at the top. The tape will hold the rounds in place when they are in the cylinder and induce hop up when the bb is fired.

Since the revolver was 290fps with .177 pellets and a very short barrel I am hoping for velocities of around 400fps.

This should be a fun project. If anyone has any imput it would be appreciated. I should start this project this week or the week after. I don't want to mess up so if missed anything completely ovious, let me know :wink:
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Unread postAuthor: Pete Zaria » Tue Oct 02, 2007 1:21 pm

Awesome project, I used to have a very similar Gamo pellet revolver.

I'm quite sure it can be done given some ingenuity, time, and materials.

I'd consider replacing the barrel altogether rather than trying to bore out the existing one for 6mm - find an aluminum arrow shaft with a real tight fit for airsoft (someone on this forum recommended an arrow recently...) and use a section of that instead.

How do you intend to do the weaver rails?

I'm worried about the power of this thing, to be honest - I have a crossman model "357" pellet revolver I use for scaring off raccoons, it'll do around 600fps... and airsoft bb's are lighter (though they have lower sectional density, they still have pretty high muzzle velocity) and would hurt like a motherchucker above 350-400fps. Be careful with this thing.

Best of luck.

Peace,
Pete Zaria.
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Unread postAuthor: jackssmirkingrevenge » Tue Oct 02, 2007 1:22 pm

Assuming you get all the bits aligned i don't see why it shouldn't work. you should take the opportunity to add a silencer while you're at it, CO2 guns are notoriously loud. The shame is the gap between the cylinder and the barrel, ah well.

edit:
I'm worried about the power of this thing, to be honest - I have a crossman model "357" pellet revolver I use for scaring off raccoons, it'll do around 600fps...


That sounds a little optimistic for a crosman, did you actually chrono it?
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Unread postAuthor: )DEMON( » Tue Oct 02, 2007 1:25 pm

Nope, fixed that by adding an oring to the end of the barrel. Seals very well :D

I might add a silencer, I know how to make them :) and that method of using pvc redicers to clamp the silencer onto the gun works very well. Getting the parts aligned should be easy, providing the drill works like it should. Well, I will use a new drill bit and my drill press. That should work.
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Unread postAuthor: ALIHISGREAT » Tue Oct 02, 2007 1:27 pm

hmm sounds cool, how are you planning to bore out the barrel?
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Unread postAuthor: )DEMON( » Tue Oct 02, 2007 1:31 pm

Pete Zaria wrote:I'd consider replacing the barrel altogether rather than trying to bore out the existing one for 6mm - find an aluminum arrow shaft with a real tight fit for airsoft (someone on this forum recommended an arrow recently...) and use a section of that instead.

How do you intend to do the weaver rails?



Ah, sorry, missed your post. I am completely replacing the existing barrel. I will get the old barrel bored out 8mm so I can insert the 6mm barrel, sorry thats what I was trying to say.

The weaver rails are plastic, they are from another bbgun. I used epoxy putty to fix those on too, you can see there is also one on there. They might be plastic, but they are very tough.

I will be carefull with the power of this thing, I can adjust the valve if need be.
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Unread postAuthor: Pete Zaria » Tue Oct 02, 2007 1:32 pm

@jack,

The crossman with the 6" said 590fps on the box. I said "around 600". I also know it'll do about 5" on (uncalibrated) homemade ballistic gel.
I only have that thing for scaring 'coons of my back deck anyway, though.

Peace,
Pete Zaria.
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Unread postAuthor: )DEMON( » Tue Oct 02, 2007 1:32 pm

ALIHISGREAT wrote:hmm sounds cool, how are you planning to bore out the barrel?


Will get it done on a lathe I think. Or however my freinds dad reccomends.
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Unread postAuthor: ALIHISGREAT » Tue Oct 02, 2007 1:35 pm

i bored some tees on my grandpa's lathe at the weekend, it might be quite hard to do depending on the length of the barrel, also the lathe would have to have a very small boring tool.
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Unread postAuthor: )DEMON( » Tue Oct 02, 2007 1:49 pm

Well I will not be doing it and I am not sure how it will be done. I don't think I have the skill to do it cleanly and I want it to be done very well.
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Unread postAuthor: Dornep » Tue Oct 02, 2007 2:56 pm

Very cool project, I'm looking to forward to seeing this thing when it's finished.

With a level, a vice, and a drill press you could probably get the barrel bored out to fit in the new barrel fairly easy.

Also about the silencer idea.. Silencers don't really work on REAL revolvers but if your's is sealed with orings it would cut down on the noise... AND you could use it to conceal your barrel instead of messing with the epoxy putty. I did this with an MP5 I had once, the thing was inaccurate as all hell so I bought some brakeline, extended the inner barrel and hid it with the silencer that came with the gun.

Once finished this thing will make the ultimate backup weapon... If I was playing against you I would make sure you hit me with your main weapon as I wouldn't want to go up against this thing :D
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Unread postAuthor: jackssmirkingrevenge » Tue Oct 02, 2007 10:10 pm

Dornep wrote:Also about the silencer idea.. Silencers don't really work on REAL revolvers but if your's is sealed with orings it would cut down on the noise...


Don't generalise ;)
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Unread postAuthor: )DEMON( » Wed Oct 03, 2007 11:08 am

Dornep wrote:AND you could use it to conceal your barrel instead of messing with the epoxy putty. I did this with an MP5 I had once, the thing was inaccurate as all hell so I bought some brakeline, extended the inner barrel and hid it with the silencer that came with the gun.

Once finished this thing will make the ultimate backup weapon... If I was playing against you I would make sure you hit me with your main weapon as I wouldn't want to go up against this thing :D


Noooooooo, that will not do for me. Without the putty the barrel will just be sticking out of the gun by itself and would be very fragile. I have a lot of experience working with epoxy putty, have used it many times. You make it seem like I am fixing the barrel onto the gun with the epoxy, I assure you this is not the case. The putty will form the new body around the barrel. I want this thing to be big, mean and tough.

I have acually used the putty I plan to use before on the revolver, it is holding the top rail on and holds the oring that seals the barrel and chamber. Which reminds me, I can't put a seal between the valve and chamber because it is a hammer valve and when open is pushed forward to seal anyway. It would disrupt the operation to add a seal.

This is actually going to be my primary. You see, my freind and I are looking into airsoft but don't have a lot of money, especially me because of the recent purchase of an electric guitar, so we are going to use pistols. He is going to get an all metal HFC pistol and I am making mine. We mainly plan to have skirmishes at each others houses. Another freind is also getting into it. I figure I will save up for a Classic army AEG, most likely the M4 or one of the MP5's. Those are sweeeeeet! I play pump in paintball, so I am used to the ammo disadvantage, no problem for me. Of course I will make something for faster loading or if it works I may look into a belt feeding mechanism. Then I would get some weaver scope rings for my 4x32 scope. Then a madbull short grenade launcher with three grenades which will cost $240, will mount that on the bottom rail :twisted: But that is what I want now, I will no dought change my mind.

Ah, by the way. The co2 seal on the valve has gone, the thing that seals the 12gram to the valve. How can I fix this?
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Unread postAuthor: spanerman » Wed Oct 03, 2007 11:30 am

soak the seal in silicone lube.....or oring it
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Unread postAuthor: jackssmirkingrevenge » Wed Oct 03, 2007 12:46 pm

)DEMON( wrote:The co2 seal on the valve has gone, the thing that seals the 12gram to the valve. How can I fix this?


2 pounds sterling and 60 pence

Though you could probably find an equivalent seal at your local hardware store.
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